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Total ozone characteristics associated with regional meteorology in West Antarctica
Atmospheric Environment 195 (2018) 78–88
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Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv
Total ozone characteristics associated with regional meteorology in West Antarctica
T
Ja-Ho Kooa, Taejin Choib, Hana Leea, Jaemin Kimc, Dha Hyun Ahna, Jhoon Kima,d, Young-Ha Kime, Changhyun Yooe, Hyunkee Hongf, Kyung-Jung Moong, Yun Gon Leec,∗ a
Department of Atmospheric Sciences, Yonsei University, Seoul, Republic of Korea Korea Polar Research Institute, Incheon, Republic of Korea c Department of Atmospheric Sciences, Chungnam National University, Daejeon, Republic of Korea d Harvard Smithsonian Center for Astrophysics, Cambridge, MA, USA e Department of Climate and Energy Systems Engineering, Ewha Womans University, Seoul, Republic of Korea f Department of Spatial Information Engineering, Pukyong National University, Busan, Republic of Korea g National Institute of Environmental Research, Incheon, Republic of Korea b
A R T I C LE I N FO
A B S T R A C T
Keywords: Total ozone column West Antarctica Weddell sea Polar vortex
We investigated the characteristics of the total ozone column (TOC) around West Antarctica (near the Weddell Sea) compared with ambient meteorological factors. For this analysis, we used ground-based and satellite TOC measurements as well as meteorology (air temperature, potential vorticity and wind field) from reanalysis data. Long-term patterns of TOC show the large year-to-year variation (e.g., maximumly ∼200 DU at King Sejong) but a steady recovering trend recently. Despite a generally consistent pattern, the TOC around West Antarctica did not correlate well between high- and low-latitude regions during austral spring; this result implies that the ozone hole area had a spatial variation over West Antarctica. The TOC pattern around West Antarctica correlated well with air temperature but showed a vertical difference; high positive correlations appeared in the lower stratosphere (maximumly R > 0.9 at ∼50–100 hPa height) showing enhanced ozone depletion in colder conditions, but negative correlations appeared in the upper stratosphere (minimum R < −0.8 at ∼5–10 hPa height) associated with the temperature dependence of ozone chemistry. The TOC also showed an interesting relationship to the potential vorticity: high positive correlation in the upper stratosphere (maximumly R > 0.9 at ∼500–600 K height) during the austral spring but a moderately negative correlation in the lower stratosphere (minimum R < −0.6 at ∼300–350 K height) during the austral summer. This peculiar pattern probably relates to the polar vortex intensification in the stratosphere and the stratosphere-troposphere airmass exchange near the tropopause. There were also some correlations with wind field (R = ∼0.4–0.6) showing air-mass mixing effects. These findings indicate a large meteorological influence on the spatiotemporal pattern of the TOC in West Antarctica.
1. Introduction The total ozone column (TOC) has been monitored over Antarctica for decades utilizing a number of ground-based and satellite remote sensing platforms. In particular, ground-based remote sensing contributed to the initial discovery of stratospheric ozone depletion over Antarctica (Farman et al., 1985). At ground-based stations, Brewer and Dobson spectrophotometers are common instruments in use for the continuous remote sensing of TOC (e.g., Kuttippurath et al., 2010, 2013; Miyagawa et al., 2014) based on the ozone absorption cross section in the ultraviolet (UV) channels. Those TOC measurements have
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been used as the standard values for the global monitoring of stratospheric ozone. A number of satellite instruments has also employed TOC observations using similar UV channels: e.g., the Total Ozone Mapping Spectrometer (TOMS, Krueger, 1989), Ozone Monitoring Instrument (OMI, Kroon et al., 2008), and Global Ozone Monitoring Experiment (GOME, Burrows et al., 1999). Intercomparison among these ground-based and satellite ozone measurements enables us to perform the analysis of long-term ozone variation (e.g., Bramstedt et al., 2003; Balis et al., 2007). Since the satellite measurement has the advantage to cover wide spatial range, intercomparison analyses are required for better usage of satellite data.
Corresponding author. E-mail address: [email protected] (Y.G. Lee).
https://doi.org/10.1016/j.atmosenv.2018.09.056 Received 18 May 2018; Received in revised form 23 September 2018; Accepted 26 September 2018 Available online 27 September 2018 1352-2310/ © 2018 Elsevier Ltd. All rights reserved.
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either Dobson or Brewer spectrophotometers (Table S1), which are optical instruments using UV solar radiation. Therefore, TOC observations in West Antarctica are not available during polar night when the solar radiation is either weak or nonexistent. For the austral spring and summer (September to March), we utilize the recent 20-year (1996–2015) measurements of TOC for the analyses in this study. Satellite TOC data have also been performed for several decades. TOMS and OMI are representative instruments utilized for monitoring TOCs since the late 1970s. From 1996 to 2015, we utilized level 3 TOC data with 1 × 1° spatial resolution from TOMS measurements onboard the Earth Probe (EP) satellite and OMI measurements onboard the Aura satellite. Satellite monitored TOCs have been validated by comparison with ground-based observations for some Antarctic stations (Balis et al., 2007; Kuttippurath et al., 2018). Due to the smaller number of Antarctic ground-based stations compared the mid-latitude, additional intercomparisons are useful and necessary. For the evaluation of TOCs, we performed an intercomparison between ground-based (by Dobson and Brewer spectrophotometers) and satellite (TOMS and OMI instruments) observations. For the validation purpose, Kuttippurath et al. (2018) already performed the precise intercomparison between the ground-based and satellite TOC measurements and suggested the statistical results of validation in detail. Our study tries to contribute to this validation task by adding one more new ground-based station, the King Sejong station (Fig. 2 and S2). Another difference of our intercomparison is the consideration of the level 3 gridded satellite data, which have a coarse resolution. Since level 3 TOC data are acquired and considered for the general ozone monitoring and data analysis due to the small data size and convenience of data treatment, the quality check with the ground-based measurement is also necessary step. Therefore, here we compared TOCs between ground-based and gridded satellite observations (level 3 data) and discuss the data quality with considering results from Kuttippurath et al. (2018), which includes the comparison of TOC between groundbased and satellite overpass observations (level 2 data). Fig. 2 shows that gridded satellite TOC measurements in the five stations correlate well with ground-based TOC measurements. Considering the comparison results with satellite overpass data in Kuttippurath et al. (2018), the correlation coefficient (R) in our study is generally similar in spite of the different period of analysis (Table S2): R = 0.97 at Marambio (R = 0.90–0.97 with overpass observations), R = 0.93 at F (R = 0.93–0.96 with overpass observations), R = 0.98 at Halley (R = 0.96–0.98 with overpass observations), and R = 0.98 at Belgrano (R = 0.94–0.98 with overpass observations). TOC measurements at the King Sejong station is first reported in this study, therefore we performed the TOC correlation analysis with both gridded and overpass satellite measurements from 1996 to 2015. As a result, the correlation of ground-based TOC is R = 0.94 with gridded satellite TOC, and R = 0.97 with satellite overpass TOC. While correlations with the satellite overpass measurement are definitely higher, correlations with gridded satellite data are also reasonably high. Root mean square error (RMSE) and mean bias error (MBE) values were also compared with results in Kuttippurath et al. (2018). All comparison results summarized in Table S2 show that the quality of gridded satellite TOC observation is good for scientific analysis. However, we can find some regional differences. TOCs at the Marambio, Halley and Belgrano stations are quite consistent, but the ozone values at the King Sejong and Faraday stations show a little variability. At the King Sejong and Faraday station, R, RMSE, and MBE becomes worse when considering the gridded data instead of overpass data, whereas other stations do not have large differences. The TOCs can vary substantially over the coast of Antarctica, where the edge of polar vortex exists (Zhang et al., 2017), and this variation seems associated with the large differences between ground-based and satellite TOC measurements at the King Sejong and Faraday station. We will examine this spatial property in greater detail during the next section. To find the meteorological influence on TOC variation, we
A significant reason for monitoring the Antarctic ozone hole was to evaluate the local risk of high UV radiation reaching the surface (Hegglin and Shepherd, 2009; Bais et al., 2018). Recently, several studies also focused on the relationship of stratospheric ozone change to large-scale atmospheric circulations and even climate variability (Shepherd, 2008). In particular, the southern annular mode, the representative climate variability in the Southern Hemisphere, is known to be strongly associated with the ozone loss (Thompson et al., 2011). Namely, the stratospheric ozone concentration affects the regional and large-scale spatiotemporal variation of atmospheric phenomena in the Southern Hemispheric and Antarctica (Son et al., 2009, 2010; Kang et al., 2011; Manatsa et al., 2013). These linkages are usually explained based on the stratosphere-troposphere exchange associated with planetary wave activity (Thompson et al., 2005; Yang et al., 2007; Kidston et al., 2015). Some issues, such as the meteorological difference between East and West Antarctica, still require a more detailed analysis for better understanding. It is important to note that the TOC exhibits strong variability at seasonal, interannual, and even longer time scales, which complicates efforts to evaluate its impact on climate (Bais et al., 2018). One representative example is the recent ozone recovery in contrast to the large decrease during the twentieth century (Yang et al., 2008; Salby et al., 2011; Solomon et al., 2016; Kuttippurath and Nair, 2017), which can alter the future climate (Perlwitz et al., 2008; McLandress et al., 2011). Year-to-year variation is also large and cannot be neglected (Huck et al., 2005). Antarctic ozone loss occasionally becomes weak due to sudden stratospheric warming, as occurred in 2002 (Hoppel et al., 2003; Kondragunta et al., 2005). This kind of irregular event can relate to peculiar atmospheric pattern changes (Konopka et al., 2005; Marchand et al., 2005). Thus, long-term continuous TOC monitoring should be investigated in addition to other meteorological and climate factors. Analyzed results will be useful for future predictions based on TOC variations. In this study, we examined the long-term measurements of TOC around the Weddell Sea in the western Antarctic region. In terms of large-scale atmospheric and climate patterns, atmospheric situations in the western Antarctic region appear connected to external forcing from mid-latitude and even tropical regions (Waugh et al., 2009; Ding et al., 2011). Additionally, the contrast of atmospheric patterns (e.g., temperature trend) between West and East Antarctica is probably attributed to the asymmetrical effect of stratospheric ozone and associated large-scale circulation (Thompson and Solomon, 2002; Steig et al., 2009). These effects imply that the TOC variation should be carefully examined with considering other atmospheric factors. Sites and data are described in Section 2. The TOC properties are examined in Section 3.1, and the relationships with meteorological factors are discussed in Section 3.2. Finally, Section 4 provides the summary and conclusions of this study. 2. Data description To examine the western Antarctic TOC observed at ground-based stations, five stations near the Weddell Sea, West Antarctica were selected for this study: King Sejong (62.13°S, 58.47°W), Marambio (64.24°S, 56.63°W), Faraday (65.25°S, 64.26°W), Halley (74.35°S, 26.93°W) and Belgrano II (77.87°S, 34.63°W, hereafter Belgrano) stations (Fig. 1). Observed TOCs at King Sejong stations were provided from the Korea polar research institute, and those from the other four stations were obtained from the data archive of the World Ozone and Ultraviolet radiation Data Centre (WOUDC). Among the five, three stations (i.e., King Sejong, Marambio, and Faraday) are located at the tip of the Antarctic Peninsula, which is on the mid-latitude side of latitude 70°S. The other two stations (Halley and Belgrano) are located near the coast of the Weddell Sea (Fig. 1) on the poleward side of 70°S. The maximum latitudinal distance between the stations is approximately 15°. The TOCs at these stations have been monitored using 79
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Fig. 1. Research Area: 5 ground-based stations near the Weddell Sea in West Antarctica.
Fig. 2. Intercomparison results (1996–2015) between ground-based TOC (Dobson or Brewer spectrophotometer) and satellite TOC (TOMS and OMI) measurements at 5 stations near the Weddell Sea. 80
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Fig. 3. Year-to-year variation of September and October (the period showing large stratospheric ozone depletion) median (a and b) and minimum (c and d) values of TOC.
investigated air temperature, potential vorticity, and wind field data at multiple heights. For these variables, we used the European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-interim) dataset (Dee et al., 2011). For air temperature and wind speed, values were obtained at 12 pressure levels from the upper to lower stratosphere (5, 7, 10, 20, 30, 50, 70, 100, 125, 150, 175, and 200 hPa). Since the potential vorticity is a dynamical quantity that is conserved for adiabatic motions on isentropic surfaces, we used the potential vorticity obtained at 12 potential temperature levels from lower to the upper stratosphere (300, 315, 330, 350, 370, 395, 430, 475, 530, 600, 700, and 850 K). All data used in these analyses were daily mean values.
Despite consistent long-term trends observed at all 5 stations, Fig. 3 shows that the year-to-year variation changes considerably from station to station, similar to inter-annual variability observed at different station measurements (Grytsai et al., 2005; Huck et al., 2005). This observation means that the pattern of ozone depletion is spatially heterogeneous. We investigated whether the relationship of TOC among monitoring stations is consistent or not, based on the correlation analysis of TOCs. For this purpose, TOCs at the King Sejong station were compared with TOCs at other stations. The TOC values at King Sejong correlated well with the TOC values at Marambio (Fig. 4a) and Faraday (Fig. 4b). Both stations are located near the King Sejong station in the Antarctic peninsula (Fig. S4). As the distance between stations increases, however, the TOC correlation became weak, as shown in the case for the Halley (Fig. 4c) and Belgrano stations (Fig. 4d). Interestingly, these low correlations were enhanced during the austral springtime (September to November) as also shown in Fig. 4c and d. During this period, the TOCs at Halley and Belgrano (the high latitude region, > 70°S) were mostly below 220 Dobson Unit (DU), which is the threshold value for determining an ozone hole (Bodeker et al., 2002; Newman et al., 2004), while the King Sejong station was only partly affected by massive ozone depletion. The TOC values at the Halley (∼74°S) station were partially similar to the ozone levels at the King Sejong station (Fig. 4c), while most of the TOCs at Belgrano (∼79°S) station had values lower than 220 DU, resulting in the weak correlation with TOCs at the King Sejong station. This regional feature of stratospheric ozone depletion is related to the distinct atmospheric differences as the latitude increases. In other words, weak correlations of the TOCs between stations north and south
3. Ozone depletion properties in West Antarctica First, temporal variations of TOC at 5 stations around the Weddell Sea were examined from 1996 to 2015 (Fig. S1). It appears that both the ground- and satellite-based TOC values have recently shown a slight increasing trend. In particular, low TOCs increased and the annual variation decreased, implying that the ozone depletion has been weakened during the last decade. Monthly median and minimum patterns of TOC in austral spring better revealed the steady increase (Fig. 3). During the austral springtime, when the ozone hole typically forms, measurements at most stations also showed the recent recovery pattern more distinctly in September than that in October (Fig. S3). This feature also supports the recent discussion regarding the beginning of stratospheric ozone recovery (Solomon et al., 2016). Among the 5 research stations, the observed TOCs were generally the lowest at Belgrano and highest at the King Sejong station. 81
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Fig. 4. Comparison of TOCs at the King Sejong station to those at the (a) Marambio, (b) Faraday, (c) Halley, and (d) Belgrano stations. Different colors indicate each month. Dashed line shows the 220 DU, the threshold value for determining the occurrence of the ozone hole. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
strength of the Antarctic polar vortex (Fig. 5 and S7). Since the TOC pattern latitudinally differs in accordance with the edge of the polar vortex (Roscoe et al., 2012), the spatial or temporal properties of TOC generally tend to be investigated at different coordinates: equivalent latitudes accounting for the potential vorticity (Nash et al., 1996). Since the polar vortex difference effect is considered at equivalent latitudes, the TOC variation at this coordinate depends primarily on chemical ozone loss by halogens generated from chlorofluorocarbons. Thus, the analysis of TOC at equivalent latitudes is recommended to monitor the extent of polar ozone hole formation via halogen chemistry, as a number of previous studies have reported (e.g., Bodeker et al., 2002; Kuttippurath and Nair, 2017). However, the lesson in this section is that meteorological conditions substantially impact the regional differences of TOC patterns around West Antarctica. Additionally, the existence of polar vortex edge was discussed, which showed a different evolution pattern from the vortex core (Roscoe et al., 2012). In other words, TOC variation can be different among closely grouped ground-based stations even though they are inside the polar vortex; these observations indicate the importance of recognizing the dynamic effects of TOC variation. Also, TOC variation can be affected by many other atmospheric dynamics and climate effects (Thompson et al., 2011), making the diagnosis of stratospheric ozone recovery more difficult and trickier (Chipperfield et al., 2017). Therefore, it appears necessary to examine the TOC pattern at each region for determining how TOCs interact with the surrounding air
of 70°S indicate that meteorological conditions associated with the stratospheric ozone depletion are not ubiquitously situated around the Weddell Sea. To confirm this idea, we performed a correlation analysis among the 5 stations using meteorological factors in a manner similar to that of the TOC comparison in Fig. 4. Figs. S5 and S6 show correlation results of 50-hPa air temperature and 850-K potential vorticity from the closest stations (King Sejong vs. Marambio) to the farthest stations (King Sejong vs. Belgrano). As expected, the air temperature and the potential vorticity values between stations close to each other had a linear correlation (e.g., Figs. S5a and S6a), while correlations between distant stations were weak (e.g., Figs. S5d and S6d). Specifically, the Belgrano station had a much lower air temperature and stronger potential vorticity than that of the King Sejong station, and this difference was particularly large during the austral spring, the ozone hole season. Considering that ozone hole events occur inside the stratospheric polar vortex, this result illustrates that the TOC variation in the higher latitude region is more strongly influenced by the intensified polar vortex but that the TOC values in the lower latitudes are not as affected by the polar vortex. We found that the latitudinal difference of TOCs, stratospheric air temperature and potential vorticity can be very large around the Weddell Sea, particularly during the austral spring. As a result, the area of the polar vortex shifts among the five western Antarctic stations. Fig. 3 shows the large year-to-year TOC differences between 2010 (high TOC) and 2011 (low TOC) which also relates to the different size and 82
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Fig. 5. Spatial distribution of monthly mean potential vorticity at the 850-K height during September between 2010 (left) and 2011 (right).
Fig. 6. Vertical profile of correlations between the TOC and air temperature for 12 pressure heights (5, 7, 10, 20, 30, 50, 70, 100, 125, 150, 175, and 200 hPa) at the (a) King Sejong, (b) Marambio, (c) Faraday, (d) Halley and (e) Belgrano stations.
conditions. Therefore, we investigated the relationship between the TOCs and meteorological data associated with polar processing.
vertical profile of air temperature, potential vorticity and wind components obtained from the ERA-Interim reanalysis data. Correlations between meteorological factors and TOCs were calculated at each vertical altitude during each month from September to March, the austral spring and summer when the interaction between the stratospheric ozone and atmospheric circulation is expected (Thompson et al., 2011).
4. Relation to the meteorological conditions As discussed in Section 3, TOC variation is closely connected to polar vortex conditions. To better examine their relationship, we used a 83
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Fig. 7. Vertical profile of correlations between the TOC and potential vorticity for 12 potential temperature heights (300, 315, 330, 350, 370, 395, 430, 475, 530, 600, 700, and 850 K) at the (a) King Sejong, (b) Marambio, (c) Faraday, (d) Halley and (e) Belgrano stations.
2008). Previous studies based on the Chapman reactions showed that upper stratospheric ozone can be abundant at lower temperatures due to the slower ozone destruction (Jonsson et al., 2004; Shepherd and Jonsson, 2008). For example, Jonsson et al. (2004) found the negative temperature dependence of O + O2 + M → O3 + M reaction. This rationale has been frequently discussed in conjunction with the increase in greenhouse gases for their impact on the stratospheric ozone levels and temperature changes (e.g., Jonsson et al., 2009; Plummer et al., 2010; Gillett et al., 2011). Some satellite limb-sounding observations also clarified this anti-correlation between ozone and air temperature in the upper stratosphere (Stolarski et al., 2012). The vertically varying structure of correlations suggests that the variation of the TOC is not attributed to only a single atmospheric feature. While the massive stratospheric ozone loss in the strong polar vortex is typically dominant, the TOC variation also has some sensitivities to other factors, implying that the change in the ozone-temperature relationship is possible depending on atmospheric conditions. In fact, the vertical shape of ozone-temperature correlations shows large month-to-month variations (Fig. 6). In austral spring, the polar vortex is intensified, and large-scale ozone depletion begins. However, the onset date of ozone depletion can differ latitudinally due to regional solar intensity differences. Therefore, lower stratospheric positive correlations in September were only high at the King Sejong, Marambio and Faraday stations. Higher latitude stations (Halley and Belgrano) did not find meaningful correlations in September because the photochemical ozone loss is not active during this period. Station measurements had high positive correlations between ozone and temperature during October in the lower stratosphere. In mid to late October, however, stations < 70° started to exhibit negative correlations in the
Fig. 6 illustrates monthly correlation patterns between the TOC and stratospheric air temperature (from 200 to 5 hPa height) at each station. In general, a large contrast can be found vertically: high positive correlation in the lower stratosphere (> ∼50 hPa) but high negative correlation in the upper stratosphere (< ∼10 hPa). Positive correlations in the lower stratosphere were consistent during the austral spring and summer, but the negative correlation in the upper stratosphere indicated a larger seasonal difference. This pattern reveals the role of atmospheric conditions related to ozone chemistry between the upper and lower stratosphere. The positive correlation between ozone/temperature in the lower stratosphere indicates strong stratospheric ozone depletion in the intensified polar vortex. Previous studies have shown that air temperature becomes quite low in the intensified polar vortex because the meridional heat exchange is restricted. The polar stratospheric cloud (PSC), composed of ice particles, can be formed in the polar vortex. This PSC can take up nitric acid (HNO3) to inhibit the formation of chlorine nitrate (ClONO2), which is the reservoir species of chlorine radical (Keeble et al., 2014). Consequently, PSC diminishes the amount of stratospheric nitrogen, referred to as a denitrification process (Salawitch et al., 1989), and contributes to the recycling of the chlorine radical in the stratosphere, which results in strong ozone depletion. This process explains the positive correlation between air temperature and ozone as discussed in some previous studies (Solomon et al., 2005, 2014). The negative correlation between ozone and air temperature in the upper stratosphere can be explained by the temperature dependence of ozone chemistry. Stratospheric ozone production and loss processes are essentially explained by the Chapman mechanism (e.g., Velasco et al., 84
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Fig. 8. Vertical profile of correlations between the TOC and zonal wind speed (U wind) for 12 pressure heights (5, 7, 10, 20, 30, 50, 70, 100, 125, 150, 175, and 200 hPa) at the (a) King Sejong, (b) Marambio, (c) Faraday, (d) Halley and (e) Belgrano stations.
transported from other areas, perturbing the strength of polar vortex. In fact, previous studies (Pan et al., 2009; Gettelman et al., 2011) have discussed the occurrence of low ozone concentration in the lower stratosphere at polar regions and showed the associated meridional transport of mid-latitudinal tropospheric air into the polar stratosphere. Pan et al. (2009) also illustrated that this intrusion of mid-latitude tropospheric air masses containing lower ozone levels is attributed to the subtropical tropopause break; the core altitude of intrusion typically appears between 370 and 400 K potential temperature height. As shown in Fig. 7, the negative correlations between the TOC and potential temperature were also found below 400 K height. This negative correlation was higher at the King Sejong, Marambio and Faraday stations than it is at the Halley and Belgrano stations, which supports that the intrusion of mid-latitude tropospheric air masses weakens inside the polar vortex. One more interesting feature is the seasonal difference; negative correlation between ozone and potential vorticity was only distinct in the austral summer, the season after the stratospheric ozone hole formation. This pattern likely occurs because the poleward lowozone intrusion is more suitable when the polar vortex is not deeply intensified. Finally, we examined the relationship of TOC with zonal (Fig. 8) and meridional (Fig. 9) wind speeds, which can describe the influence of air-mass transport or mixing processes to TOC variations. Correlations with wind speed were not as strong as those with the air temperature (Fig. 6) and potential vorticity (Fig. 7), but some interesting features were still found. Between approximately 20 and 50 hPa height, we found rather high positive correlations during September at the King Sejong, Marambio and Faraday stations (Fig. 8a, b, and 8c) and during October at the Halley and Belgrano stations (Fig. 8d and e). Scatterplots between the TOC and zonal wind speed (Fig. S8) show that the strongly
upper stratosphere while stations > 70° did not. All five stations began to show high negative ozone-temperature correlations in the upper stratosphere in November. This negative correlation continued until December and weakened during the austral summer due to warmer temperatures (Fig. S5) which do not contribute to the ozone production in the upper stratosphere. In contrast to the upper stratosphere, the lower stratosphere had a consistent positive correlation through the austral spring and summer, implying the existence of a potential factor to retain the negative correlation between the TOC and air temperature. This seasonal variation of ozone-temperature correlations will be further discussed with continued analysis using other meteorological properties. In addition, we performed a similar correlation analysis using TOC and potential vorticity. Fig. 7 shows the vertical distribution of ozone and potential vorticity correlations following potential temperature height. Similar to the ozone and temperature correlations (Fig. 7), large contrast patterns were also found vertically: high positive correlation in the lower and middle stratosphere (> ∼400 K) but high negative correlations near the tropopause (< ∼400 K). High positive correlations in the lower and middle stratosphere clearly appear during the austral spring, with a monthly shift between lower and higher latitudes: September to November at the King Sejong, Marambio, and Faraday stations, and October to November at the Halley and Belgrano stations. The positive correlations become quite small during the austral summer, indicating that the weakened polar vortex merely affects the stratospheric ozone depletion. Meanwhile, contrasting negative correlations were found near the tropopause, meaning that the TOC decreases as the polar vortex weakens, implying the existence of mixing process. This feature may indicate that air masses having lower ozone concentrations can be 85
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Fig. 9. Vertical profile of correlations between the TOC and meridional wind speed (V wind) for 12 pressure heights (5, 7, 10, 20, 30, 50, 70, 100, 125, 150, 175, and 200 hPa) at the (a) King Sejong, (b) Marambio, (c) Faraday, (d) Halley and (e) Belgrano stations.
processes combine to vary the TOCs measured around the Weddell Sea, West Antarctica. In brief, the extent of halogen-related ozone loss in the lower and middle stratosphere is generally controlled by the strength of the polar vortex. In the upper stratosphere, the basic Chapman mechanism better explains ozone concentration as a function of temperature dependence. Near the tropopause, we found the impact from the meridional intrusion of mid-latitudinal tropospheric air masses had lower ozone concentrations than those of the stratospheric air masses. Correlations with the wind field provided some ideas for how the transport or mixing of Antarctic air masses affect the regional difference of TOC variation around the Weddell Sea. Each factor had a different spatial scale and seasonal impact, which resulted in the generally consistent but regionally distinguishing relationship to the TOC in West Antarctica. As widely known, stratospheric ozone in the Southern Hemisphere has been significantly examined in terms of the feedback with the climate variability and large-scale circulation. Considering the sensitivity of western Antarctic atmosphere to climate change (Turner et al., 2005; Ding et al., 2011), a more thorough investigation of western Antarctic ozone patterns will be required. Based on results from this study, the TOC in West Antarctica can change by several atmospheric patterns: halogen-related chemical loss in the polar vortex, the Chapman mechanism in the upper stratosphere, stratosphere-troposphere exchange between polar and mid-latitude regions, and meridional air-mass mixing. The complex interconnection and feedback processes among various southern hemispheric patterns should be discussed further with incorporating TOC properties in West Antarctica. Therefore, it appears that acquired data from long-term TOC observations will be beneficial to the future climate research for Antarctica and the Southern Hemisphere, which highlights the importance of continuous ozone
depleted TOC with weak zonal wind speeds can lead to positive correlations. This pattern likely appears because the halogen-related chemical loss of stratospheric ozone in the vortex increases in the absence of mixing with outside air masses. We also realized that correlations between the TOC and zonal wind speed also adequately detect the period having the largest decrease in stratospheric ozone, considering that median TOC values are actually the lowest in September at stations < 70° and in October at stations > 70° (Fig. 3). From the correlation between the TOC and meridional wind speed (Fig. 9), summertime (January to March) negative correlations from 20 to 50 hPa height was the most prominent pattern, particularly at the stations < 70°. Scatterplots between the TOC and meridional wind speed (Fig. S9) illustrated that this negative correlation indicates a high ozone supply with the poleward wind (i.e., negative meridional wind speed) and low ozone intrusion with the equatorward wind (i.e., positive meridional wind speed). This pattern appears to be reasonable considering that the TOC is usually lower near the South Pole than the ozone-rich conditions in the mid- and lower latitudes. In Fig. 6, we showed that the ozone-temperature correlation in the lower stratosphere is still positive during austral summer when the polar vortex is weakened. This pattern can be explained by the negative summertime correlation between the TOC and meridional wind speed because the ozone-rich air masses in the mid-latitude are warmer than the polar ozone-poor air masses. It can be presumed that the meridional air mixing can be activated after breaking the polar vortex; summertime high negative correlations between TOC and meridional wind in the stratosphere are also expected. Further investigation will be necessary to explain why the highest correlation with meridional wind appears in February. Based on these analyses, we found that multiple atmospheric 86
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monitoring.
Chipperfield, M.P., Bekki, S., Dhomse, S., Harris, N.R.P., Hassler, B., Hossaini, R., Steinbrecht, W., Thiéblemont, R., Weber, M., 2017. Detecting recovery of the stratospheric ozone layer. Nature 549, 211–218. https://doi.org/10.1038/nature23681. Dee, D.P., Uppala, S.M., Simmons, A.J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M.A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A.C.M., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A.J., Haimberger, L., Healy, S.B., Hersbach, H., Hólm, E.V., Isaksen, L., Kållberg, P., Köhler, M., Matricardi, M., McNally, A.P., Monge-Sanz, B.M., Morcrette, J.-J., Park, B.-K., Peubey, C., de Rosnay, P., Tavolato, C., Thépaut, J.-N., Vitart, F., 2011. The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Q. J. Roy. Meteorol. Soc. 137, 553–597. Ding, Q., Steig, E.J., Battisti, D.S., Küttel, M., 2011. Winter warming in west Antarctica caused by central tropical Pacific warming. Nat. Geosci. 4, 398–403. https://doi.org/ 10.1038/NGEO1129. Farman, J.C., Gardiner, B.G., Shanklin, J.D., 1985. Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction. Nature 315, 207–210. Gettelman, A., Hoor, P., Pan, L.L., Randel, WlJ., Hegglin, M.I., Birner, T., 2011. The extratropical upper troposphere and lower stratosphere. Rev. Geophys. 49, RG3003. https://doi.org/10.1029/2011RG000355. Gillett, N.P., Akiyoshi, H., Bekki, S., Braesicke, P., Eyring, V., Garcia, R., Karpechko, A.Y., McLinden, C.A., Morgenstern, O., Plummer, D.A., Pyle, J.A., Rozanov, E., Scinocca, J., Shibata, K., 2011. Attribution of observed changes in stratospheric ozone and temperature. Atmos. Chem. Phys. 11, 599–609. https://doi.org/10.5194/acp-11-5992011. Grytsai, A., Grytsai, Z., Evtushevsky, A., Milinevsky, G., 2005. Interannual variability of planetary waves in the ozone layer at 65°S. Int. J. Rem. Sens. 26, 3377–3387. https:// doi.org/10.1080/01431160500076350. Hegglin, M.I., Shepherd, T.G., 2009. Large climate-induced changes in ultraviolet index and stratosphere-to-troposphere ozone flux. Nat. Geosci. 2, 687–691. https://doi.org/ 10.1038/ngeo604. Hoppel, K., Bevilacqua, R., Allen, D., Nedoluha, G., Randall, C., 2003. POAM III observations of the anomalous 2002 Antarctic ozone hole. Geophys. Res. Lett. 30, 1394. https://doi.org/10.1029/2003GL016899. Huck, P.E., McDonald, A.J., Bodeker, G.E., Struthers, H., 2005. Interannual variability in Antarctic ozone depletion controlled by planetary waves and polar temperature. Geophys. Res. Lett. 32, L13819. https://doi.org/10.1029/2005GL022943. Jonsson, A.I., de Grandpre, J., Fomichev, V.I., McConnell, J.C., Beagley, S.R., 2004. Doubled CO2-induced cooling in the middle atmosphere: photochemical analysis of the ozone radiative feedback. J. Geophys. Res. 109, D24103. https://doi.org/10. 1029/2004JD005093. Jonsson, A.I., Fomichev, V.I., Shepherd, T.G., 2009. The effect of nonlinearity in CO2 heating rates on the attribution of stratospheric ozone and temperature changes. Atmos. Chem. Phys. 9, 8447–8452. Kang, S.M., Polvani, L.M., Fyfe, J.C., Sigmond, M., 2011. Impact of polar ozone depletion on subtropical precipitation. Science 332, 951–954. https://doi.org/10.1126/ science.1202131. Keeble, J., Braesicke, P., Abraham, N.L., Roscoe, H.K., Pyle, J.A., 2014. The impact of polar stratospheric ozone loss on Southern Hemisphere stratospheric circulation and climate. Atmos. Chem. Phys. 14, 13705–13717. https://doi.org/10.5194/acp-1413705-2014. Kidston, J., Scaife, A.A., Hardiman, S.C., Mitchell, D.M., Butchart, N., Baldwin, M.P., Gray, L.J., 2015. Stratospheric influence on tropospheric jet streams, storm tracks and surface weather. Nat. Geosci. 8, 433–440. https://doi.org/10.1038/NGEO2424. Kondragunta, S., Flynn, L.E., Neuendorffer, A., Miller, A.J., Long, C., Nagataki, R., Zhou, S., Beck, T., Beach, E., McPeters, R., Stolarski, R., Bhartia, P.K., DeLand, M.T., Huang, L.-K., 2005. Vertical structure of the anomalous 2002 Antarctic ozone hole. J. Atmos. Sci. 62, 801–811. Konopka, P., Grooβ, J.-U., Hoppel, K.W., Steinhorst, H.-M., Müller, R., 2005. Mixing and chemical ozone loss during and after the Antarctic polar vortex major warming in September 2002. J. Atmos. Sci. 62, 848–859. Kroon, M., Petropavlovskikh, I., Shetter, R., Hall, S., Ulimann, K., Veefkind, J.P., McPeters, R.D., Browell, E.V., Levelt, P.F., 2008. OMI total ozone column validation with Aura-AVE CAFS observations. J. Geophys. Res. Atmos. 113, D15S13. https:// doi.org/10.1029/2007JD008795. Krueger, A.J., 1989. The global distribution of total ozone: TOMS satellite measurements. Planet. Space Sci. 37, 1555–1565. Kuttippurath, J., Nair, P.J., 2017. The signs of Antarctic ozone hole recovery. Sci. Rep. 7, 585. https://doi.org/10.1038/s41598-017-00722-7. Kuttippurath, J., Goutail, F., Pommereau, J.-P., Lefevre, F., Roscoe, H.K., Pazmino, A., Feng, W., Chipperfield, M.P., Godin-Beekmann, S., 2010. Estimation of Antarctic ozone loss from ground-based total column measurements. Atmos. Chem. Phys. 10, 6569–6581. Kuttippurath, J., Lefevre, F., Pommereau, J.-P., Roscoe, H.K., Goutali, F., Pazmino, A., Shanklin, J.D., 2013. Antarctic ozone loss in 1979-2010: first sign of ozone recovery. Atmos. Chem. Phys. 13, 1625–1635. Kuttippurath, J., Kumar, P., Nair, P.J., Chakraborty, A., 2018. Accuracy of satellite measurements in polar vortex conditions: comparisons with ground-based measurements. Remote Sens. Environ. 209, 648–659. https://doi.org/10.1016/j.rse.2018.02. 054. Manatsa, D., Morioka, Y., Behera, S.K., Yamagata, T., Matarira, C.H., 2013. Link between Antarctic ozone depletion and summer warming over southern Africa. Nat. Geosci. 6, 934–939. https://doi.org/10.1038/NGEO1968. Marchand, M., Bekki, S., Pazmino, A., Lefévre, F., Godin-Beekmann, S., Hauchecorne, A., 2005. Model simulations of the impact of the 2002 Antarctic ozone hole on the midlatitudes. J. Atmos. Sci. 62, 871–884. McLandress, C., Shepherd, T.G., Scinocca, J.F., Plummer, D.A., Sigmond, M., Jonsson,
5. Summary and conclusion This study investigated the properties of western Antarctic TOC levels using ground-based and satellite measurements near the Weddell Sea. On average, satellite gridded TOCs showed high correlation with the ground-based measured TOCs (R = ∼0.96) with MBE less than 7 DU. Additionally, the connection of spatiotemporal TOC variation to the ambient air conditions were examined using an auxiliary meteorological dataset. Validated TOCs around the Weddell Sea revealed the positive trend in the austral spring. However, there were some regional differences of TOC variations among stations because the border of the polar vortex oscillates over this area. Correlation analyses using several meteorological factors provided a number of interesting characteristics showing how the TOC increases or decreases according to the air conditions. Correlations with the air temperature (maximumly R > 0.9 at ∼50–100 hPa height, and minimum R < −0.8 at ∼5–10 hPa height) primarily indicated the activity of stratospheric chemical ozone depletion or formation. Correlations with the potential vorticity (maximumly R > 0.9 at ∼500–600 K height, and minimum R < −0.6 at ∼300–350 K height) and the wind field (R = ∼0.6 at maximum) depicted the influence of the polar vortex or the effect of meridional mixing on TOC variation. The variation of western Antarctic TOC was temporally (seasonally) and spatially (latitudinally or vertically) different. Thus, we suggest that TOC analysis can provide a number of useful tips for better understanding of Antarctic atmospheric patterns. Considering many unknowns regarding the connection between TOC variation and climate patterns, the ground- and satellite-based monitoring of Antarctic TOC levels should be maintained in the future. Long-term TOC measurements at the King Sejong station, first reported in this study, will be continued as one of efforts for contributing to the global monitoring network. Acknowledgements This study was supported by the Korea Polar Research Institute (KOPRI, PE17010) and the Korea Meteorological Administration Research and Development Program (KMIPA 2015-5170). Appendix A. Supplementary data Supplementary data to this article can be found online at https:// doi.org/10.1016/j.atmosenv.2018.09.056. References Bais, A.F., Lucas, R.M., Bornman, J.F., Williamson, C.E., Sulzberger, B., Austin, A.T., Wilson, S.R., Andrady, A.L., Bernhard, G., McKenzie, R.L., Aucamp, P.J., Madronich, S., Neale, R.E., Yazar, S., Young, A.R., de Gruijl, F.R., Norval, M., Takizawa, Y., Barnes, P.W., Robson, T.M., Robinson, S.A., Ballaré, C.L., Flint, S.D., Neale, P.J., Hylander, S., Rose, K.C., Wängberg, S.-Å., Häder, D.-P., Worrest, R.C., Zepp, R.G., Paul, N.D., Cory, R.M., Solomon, K.R., Longstreth, J., Pandey, K.K., Redhwi, H.H., Torikai, A., Heikkilä, A.M., 2018. Environmental effects of ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2017. Photochem. Photobiol. Sci. 17, 127–179. Balis, D., Kroon, M., Koukouli, M.E., Brinksma, E.J., Labow, G., Veefkind, J.P., McPeters, R.D., 2007. Validation of Ozone Monitoring Instrument total ozone column measurements using Brewer and Dobson spectrophotometer ground-based observations. J. Geophys. Res. 112, D24S46. https://doi.org/10.1029/2007JD008796. Bodeker, G.E., Struthers, H., Connor, B.J., 2002. Dynamical containment of Antarctic ozone depletion. Geophys. Res. Lett. 29, 1098. https://doi.org/10.1029/ 2001GL014206. Bramstedt, K., Gleason, J., Loyola, D., Thomas, W., Bracher, A., Weber, M., Burrows, J.P., 2003. Comparison of total ozone from the satellite instruments GOME and TOMS with measurements from the Dobson network 1996-2000. Atmos. Chem. Phys. 3, 1409–1419. Burrows, J.P., Weber, M., Buchwitz, M., Rozanov, V., Ladstätter-Weiβenmayer, A., Richter, A., DeBeek, R., Hoogen, R., Bramstedt, K., Eichmann, K.-U., Eisinger, M., 1999. The global ozone monitoring experiment (GOME): mission concept and first scientific results. J. Atmos. Sci. 56, 151–175.
87
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J.-H. Koo et al.
Son, S.-W., Tandon, N.F., Polvani, L.M., Waugh, D.W., 2009. Ozone hole and southern hemisphere climate change. Geophys. Res. Lett. 36, L15705. Son, S.-W., Gerber, E.P., Perlwitz, J., Polvani, L.M., Gillett, N.P., Seo, K.‐H., Eyring, V., Shepherd, T.G., Waugh, D., Akiyoshi, H., Austin, J., Baumgaertner, A., Bekki, S., Braesicke, P., Bruhl, C., Butchart, N., Chipperfield, M.P., Cugnet, D., Dameris, M., Dhomse, S., Frith, S., Garny, H., Garcia, R., Hardiman, S.C., Jockel, P., Lamarque, J.F., Mancini, E., Marchand, M., Michou, M., Nakamura, T., Morgenstern, O., Pitari, G., Plummer, D.A., Pyle, J., Rozanov, E., Scinocca, J.F., Shibata, K., Smale, D., Teyssedre, H., Tian, W., Yamashita, Y., 2010. Impact of stratospheric ozone on Southern Hemisphere circulation change: a multimodel assessment. J. Geophys. Res. 115, D00M07. Steig, E.J., Schneider, D.P., Rutherford, S.D., Mann, M.E., Comiso, J.C., Shindell, D.T., 2009. Warming of the Antarctic ice-sheet surface since the 1957 international geophysical year. Nature 457, 459–462. https://doi.org/10.1038/nature07669. Stolarski, R.S., Douglass, A.R., Remsberg, E.E., Livesey, N.J., Gille, J.C., 2012. Ozone temperature correlations in the upper stratosphere as a measure of chlorine content. J. Geophys. Res. 117, D10305. https://doi.org/10.1029/2012JD017456. Thompson, D.W.J., Solomon, S., 2002. Interpretation of recent Southern Hemisphere climate change. Science 296, 895–899. Thompson, D.W.J., Baldwin, M.P., Solomon, S., 2005. Stratosphere–troposphere coupling in the southern hemisphere. J. Atmos. Sci. 62, 708–715. Thompson, D.W.J., Solomon, S., Kushner, P.J., England, M.H., Grise, K.M., Karoly, D.J., 2011. Signatures of the Antarctic ozone hole in Southern Hemisphere surface climate change. Nat. Geosci. 4, 741–749. Turner, J., Colwell, S.R., Marchall, G.J., Lachlan-cope, T.A., Carleton, A.M., Jones, P.D., Lagun, V., Reid, P.A., Iagovkina, S., 2005. Antarctic climate change during the last 50 years. Int. J. Climatol. 25, 279–294. https://doi.org/10.1002/joc.1130. Velasco, R.M., Uribe, F.J., Pérez-Chavela, E., 2008. Stratospheric ozone dynamics according to the Chapman mechanism. J. Math. Chem. 44, 529–539. https://doi.org/ 10.1007/s10910-007-9326-7. Waugh, D.W., Oman, L., Kawa, S.R., Stolarski, R.S., Pawson, S., Douglass, A.R., Newman, P.A., Nielsen, J.E., 2009. Impacts of climate change on stratospheric ozone recovery. Geophys. Res. Lett. 36, L03805. https://doi.org/10.1029/2008GL036223. Yang, X.-Y., Huang, R.X., Wang, D.X., 2007. Decadal changes of wind stress over the Southern Ocean associated with Antarctic ozone depletion. J. Clim. 20, 3395–3410. Yang, E.-S., Cunnold, D.M., Newchurch, M.J., Salawitch, R.J., McCormick, M.P., Russell III, J.M., Zawodny, J.M., Oltmans, S.J., 2008. First stage of Antarctic ozone recovery. J. Geophys. Res. 113, D20308. https://doi.org/10.1029/2007JD009675. Zhang, Y., Li, J., Zhou, L., 2017. The relationship between polar vortex and ozone depletion in the Antarctic stratosphere during the period 1979-2016. Adv. Meteorol. 2017, 3078079. https://doi.org/10.1155/2017/3078079.
A.I., Reader, M.C., 2011. Separating the dynamical effects of climate change and ozone depletion. Part II: southern Hemisphere troposphere. J. Clim. 24, 1850–1868. Miyagawa, K., Petropavlovskikh, I., Evans, R.D., Long, C., Wild, J., Manney, G.L., Daffer, W.H., 2014. Long-term changes in the upper stratospheric ozone at Syowa, Antarctica. Atmos. Chem. Phys. 14, 3945–3968. https://doi.org/10.5194/acp-143945-2014. Nash, E.R., Newman, P.A., Rosenfield, J.E., Schoeberl, M.R., 1996. An objective determination of the polar vortex using Ertel's potential vorticity. J. Geophys. Res. 101, 9471–9478. Newman, P.A., Kawa, S.R., Nash, E.R., 2004. On the size of the Antarctic ozone hole. Geophys. Res. Lett. 31, L21104. https://doi.org/10.1029/2004GL020596. Pan, L.L., Randel, W.J., Gille, J.C., Hall, W.D., Nardi, B., Massie, S., Yudin, V., Khosravi, R., Konopka, P., Tarasick, D., 2009. Tropospheric intrusions associated with the secondary tropopause. J. Geophys. Res. 114, D10302. https://doi.org/10.1029/ 2008JD011374. Perlwitz, J., Pawson, S., Fogt, R.L., Nielsen, J.E., Neff, W.D., 2008. Impact of stratospheric ozone hole recovery on Antarctic climate. Geophys. Res. Lett. 35, L08714. https:// doi.org/10.1029/2008GL033317. Plummer, D.A., Scinocca, J.F., Shepherd, T.G., Raeder, M.C., Jonsson, A.I., 2010. Quantifying the contributions to stratospheric ozone changes from ozone depleting substances and greenhouse gases. Atmos. Chem. Phys. 10, 8803–8820. https://doi. org/10.5194/acp-10-8803-2010. Roscoe, H.K., Feng, W., Chipperfield, M.P., Trainic, M., Shuckburgh, E.F., 2012. The existence of the edge region of the Antarctic stratospheric vortex. J. Geophys. Res. 117, D04301. https://doi.org/10.1029/2011JD015940. Salawitch, R.J., Gobbi, G.P., Wofsy, S.C., McElroy, M.B., 1989. Denitrification in the Antarctic stratosphere. Nature 339, 525–527. Salby, M., Titova, E., Deschamps, L., 2011. Rebound of Antarctic ozone. Geophys. Res. Lett. 38, L09702. https://doi.org/10.1029/2011GL047266. Shepherd, T.G., 2008. Dynamics, stratospheric ozone, and climate change. Atmos.-Ocean 46, 117–138. https://doi.org/10.3137/ao.460106. Shepherd, T.G., Jonsson, A.I., 2008. On the attribution of stratospheric ozone and temperature changes to changes in ozone-depleting substances and well-mixed greenhouse gases. Atmos. Chem. Phys. 8, 1435–1444. Solomon, S., Portmann, R.W., Sasaki, T., Hofmann, D.J., Thompson, D.W.J., 2005. Four decades of ozonesonde measurements over Antarctica. J. Geophys. Res. 110, D21311. https://doi.org/10.1029/2005JD005917. Solomon, S., Haskins, J., Ivy, D.J., Min, F., 2014. Fundamental differences between Arctic and Antarctic ozone depletion. Proc. Natl. Acad. Sci. U.S.A. 111, 6220–6225. Solomon, S., Ivy, D.J., Kinnison, D., Mills, M.J., Neely III, R.R., Schmidt, A., 2016. Emergence of healing in the Antarctic ozone layer. Science 353, 269–274.
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Total ozone characteristics associated with regional meteorology in West Antarctica
T
Ja-Ho Kooa, Taejin Choib, Hana Leea, Jaemin Kimc, Dha Hyun Ahna, Jhoon Kima,d, Young-Ha Kime, Changhyun Yooe, Hyunkee Hongf, Kyung-Jung Moong, Yun Gon Leec,∗ a
Department of Atmospheric Sciences, Yonsei University, Seoul, Republic of Korea Korea Polar Research Institute, Incheon, Republic of Korea c Department of Atmospheric Sciences, Chungnam National University, Daejeon, Republic of Korea d Harvard Smithsonian Center for Astrophysics, Cambridge, MA, USA e Department of Climate and Energy Systems Engineering, Ewha Womans University, Seoul, Republic of Korea f Department of Spatial Information Engineering, Pukyong National University, Busan, Republic of Korea g National Institute of Environmental Research, Incheon, Republic of Korea b
A R T I C LE I N FO
A B S T R A C T
Keywords: Total ozone column West Antarctica Weddell sea Polar vortex
We investigated the characteristics of the total ozone column (TOC) around West Antarctica (near the Weddell Sea) compared with ambient meteorological factors. For this analysis, we used ground-based and satellite TOC measurements as well as meteorology (air temperature, potential vorticity and wind field) from reanalysis data. Long-term patterns of TOC show the large year-to-year variation (e.g., maximumly ∼200 DU at King Sejong) but a steady recovering trend recently. Despite a generally consistent pattern, the TOC around West Antarctica did not correlate well between high- and low-latitude regions during austral spring; this result implies that the ozone hole area had a spatial variation over West Antarctica. The TOC pattern around West Antarctica correlated well with air temperature but showed a vertical difference; high positive correlations appeared in the lower stratosphere (maximumly R > 0.9 at ∼50–100 hPa height) showing enhanced ozone depletion in colder conditions, but negative correlations appeared in the upper stratosphere (minimum R < −0.8 at ∼5–10 hPa height) associated with the temperature dependence of ozone chemistry. The TOC also showed an interesting relationship to the potential vorticity: high positive correlation in the upper stratosphere (maximumly R > 0.9 at ∼500–600 K height) during the austral spring but a moderately negative correlation in the lower stratosphere (minimum R < −0.6 at ∼300–350 K height) during the austral summer. This peculiar pattern probably relates to the polar vortex intensification in the stratosphere and the stratosphere-troposphere airmass exchange near the tropopause. There were also some correlations with wind field (R = ∼0.4–0.6) showing air-mass mixing effects. These findings indicate a large meteorological influence on the spatiotemporal pattern of the TOC in West Antarctica.
1. Introduction The total ozone column (TOC) has been monitored over Antarctica for decades utilizing a number of ground-based and satellite remote sensing platforms. In particular, ground-based remote sensing contributed to the initial discovery of stratospheric ozone depletion over Antarctica (Farman et al., 1985). At ground-based stations, Brewer and Dobson spectrophotometers are common instruments in use for the continuous remote sensing of TOC (e.g., Kuttippurath et al., 2010, 2013; Miyagawa et al., 2014) based on the ozone absorption cross section in the ultraviolet (UV) channels. Those TOC measurements have
∗
been used as the standard values for the global monitoring of stratospheric ozone. A number of satellite instruments has also employed TOC observations using similar UV channels: e.g., the Total Ozone Mapping Spectrometer (TOMS, Krueger, 1989), Ozone Monitoring Instrument (OMI, Kroon et al., 2008), and Global Ozone Monitoring Experiment (GOME, Burrows et al., 1999). Intercomparison among these ground-based and satellite ozone measurements enables us to perform the analysis of long-term ozone variation (e.g., Bramstedt et al., 2003; Balis et al., 2007). Since the satellite measurement has the advantage to cover wide spatial range, intercomparison analyses are required for better usage of satellite data.
Corresponding author. E-mail address: [email protected] (Y.G. Lee).
https://doi.org/10.1016/j.atmosenv.2018.09.056 Received 18 May 2018; Received in revised form 23 September 2018; Accepted 26 September 2018 Available online 27 September 2018 1352-2310/ © 2018 Elsevier Ltd. All rights reserved.
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either Dobson or Brewer spectrophotometers (Table S1), which are optical instruments using UV solar radiation. Therefore, TOC observations in West Antarctica are not available during polar night when the solar radiation is either weak or nonexistent. For the austral spring and summer (September to March), we utilize the recent 20-year (1996–2015) measurements of TOC for the analyses in this study. Satellite TOC data have also been performed for several decades. TOMS and OMI are representative instruments utilized for monitoring TOCs since the late 1970s. From 1996 to 2015, we utilized level 3 TOC data with 1 × 1° spatial resolution from TOMS measurements onboard the Earth Probe (EP) satellite and OMI measurements onboard the Aura satellite. Satellite monitored TOCs have been validated by comparison with ground-based observations for some Antarctic stations (Balis et al., 2007; Kuttippurath et al., 2018). Due to the smaller number of Antarctic ground-based stations compared the mid-latitude, additional intercomparisons are useful and necessary. For the evaluation of TOCs, we performed an intercomparison between ground-based (by Dobson and Brewer spectrophotometers) and satellite (TOMS and OMI instruments) observations. For the validation purpose, Kuttippurath et al. (2018) already performed the precise intercomparison between the ground-based and satellite TOC measurements and suggested the statistical results of validation in detail. Our study tries to contribute to this validation task by adding one more new ground-based station, the King Sejong station (Fig. 2 and S2). Another difference of our intercomparison is the consideration of the level 3 gridded satellite data, which have a coarse resolution. Since level 3 TOC data are acquired and considered for the general ozone monitoring and data analysis due to the small data size and convenience of data treatment, the quality check with the ground-based measurement is also necessary step. Therefore, here we compared TOCs between ground-based and gridded satellite observations (level 3 data) and discuss the data quality with considering results from Kuttippurath et al. (2018), which includes the comparison of TOC between groundbased and satellite overpass observations (level 2 data). Fig. 2 shows that gridded satellite TOC measurements in the five stations correlate well with ground-based TOC measurements. Considering the comparison results with satellite overpass data in Kuttippurath et al. (2018), the correlation coefficient (R) in our study is generally similar in spite of the different period of analysis (Table S2): R = 0.97 at Marambio (R = 0.90–0.97 with overpass observations), R = 0.93 at F (R = 0.93–0.96 with overpass observations), R = 0.98 at Halley (R = 0.96–0.98 with overpass observations), and R = 0.98 at Belgrano (R = 0.94–0.98 with overpass observations). TOC measurements at the King Sejong station is first reported in this study, therefore we performed the TOC correlation analysis with both gridded and overpass satellite measurements from 1996 to 2015. As a result, the correlation of ground-based TOC is R = 0.94 with gridded satellite TOC, and R = 0.97 with satellite overpass TOC. While correlations with the satellite overpass measurement are definitely higher, correlations with gridded satellite data are also reasonably high. Root mean square error (RMSE) and mean bias error (MBE) values were also compared with results in Kuttippurath et al. (2018). All comparison results summarized in Table S2 show that the quality of gridded satellite TOC observation is good for scientific analysis. However, we can find some regional differences. TOCs at the Marambio, Halley and Belgrano stations are quite consistent, but the ozone values at the King Sejong and Faraday stations show a little variability. At the King Sejong and Faraday station, R, RMSE, and MBE becomes worse when considering the gridded data instead of overpass data, whereas other stations do not have large differences. The TOCs can vary substantially over the coast of Antarctica, where the edge of polar vortex exists (Zhang et al., 2017), and this variation seems associated with the large differences between ground-based and satellite TOC measurements at the King Sejong and Faraday station. We will examine this spatial property in greater detail during the next section. To find the meteorological influence on TOC variation, we
A significant reason for monitoring the Antarctic ozone hole was to evaluate the local risk of high UV radiation reaching the surface (Hegglin and Shepherd, 2009; Bais et al., 2018). Recently, several studies also focused on the relationship of stratospheric ozone change to large-scale atmospheric circulations and even climate variability (Shepherd, 2008). In particular, the southern annular mode, the representative climate variability in the Southern Hemisphere, is known to be strongly associated with the ozone loss (Thompson et al., 2011). Namely, the stratospheric ozone concentration affects the regional and large-scale spatiotemporal variation of atmospheric phenomena in the Southern Hemispheric and Antarctica (Son et al., 2009, 2010; Kang et al., 2011; Manatsa et al., 2013). These linkages are usually explained based on the stratosphere-troposphere exchange associated with planetary wave activity (Thompson et al., 2005; Yang et al., 2007; Kidston et al., 2015). Some issues, such as the meteorological difference between East and West Antarctica, still require a more detailed analysis for better understanding. It is important to note that the TOC exhibits strong variability at seasonal, interannual, and even longer time scales, which complicates efforts to evaluate its impact on climate (Bais et al., 2018). One representative example is the recent ozone recovery in contrast to the large decrease during the twentieth century (Yang et al., 2008; Salby et al., 2011; Solomon et al., 2016; Kuttippurath and Nair, 2017), which can alter the future climate (Perlwitz et al., 2008; McLandress et al., 2011). Year-to-year variation is also large and cannot be neglected (Huck et al., 2005). Antarctic ozone loss occasionally becomes weak due to sudden stratospheric warming, as occurred in 2002 (Hoppel et al., 2003; Kondragunta et al., 2005). This kind of irregular event can relate to peculiar atmospheric pattern changes (Konopka et al., 2005; Marchand et al., 2005). Thus, long-term continuous TOC monitoring should be investigated in addition to other meteorological and climate factors. Analyzed results will be useful for future predictions based on TOC variations. In this study, we examined the long-term measurements of TOC around the Weddell Sea in the western Antarctic region. In terms of large-scale atmospheric and climate patterns, atmospheric situations in the western Antarctic region appear connected to external forcing from mid-latitude and even tropical regions (Waugh et al., 2009; Ding et al., 2011). Additionally, the contrast of atmospheric patterns (e.g., temperature trend) between West and East Antarctica is probably attributed to the asymmetrical effect of stratospheric ozone and associated large-scale circulation (Thompson and Solomon, 2002; Steig et al., 2009). These effects imply that the TOC variation should be carefully examined with considering other atmospheric factors. Sites and data are described in Section 2. The TOC properties are examined in Section 3.1, and the relationships with meteorological factors are discussed in Section 3.2. Finally, Section 4 provides the summary and conclusions of this study. 2. Data description To examine the western Antarctic TOC observed at ground-based stations, five stations near the Weddell Sea, West Antarctica were selected for this study: King Sejong (62.13°S, 58.47°W), Marambio (64.24°S, 56.63°W), Faraday (65.25°S, 64.26°W), Halley (74.35°S, 26.93°W) and Belgrano II (77.87°S, 34.63°W, hereafter Belgrano) stations (Fig. 1). Observed TOCs at King Sejong stations were provided from the Korea polar research institute, and those from the other four stations were obtained from the data archive of the World Ozone and Ultraviolet radiation Data Centre (WOUDC). Among the five, three stations (i.e., King Sejong, Marambio, and Faraday) are located at the tip of the Antarctic Peninsula, which is on the mid-latitude side of latitude 70°S. The other two stations (Halley and Belgrano) are located near the coast of the Weddell Sea (Fig. 1) on the poleward side of 70°S. The maximum latitudinal distance between the stations is approximately 15°. The TOCs at these stations have been monitored using 79
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Fig. 1. Research Area: 5 ground-based stations near the Weddell Sea in West Antarctica.
Fig. 2. Intercomparison results (1996–2015) between ground-based TOC (Dobson or Brewer spectrophotometer) and satellite TOC (TOMS and OMI) measurements at 5 stations near the Weddell Sea. 80
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Fig. 3. Year-to-year variation of September and October (the period showing large stratospheric ozone depletion) median (a and b) and minimum (c and d) values of TOC.
investigated air temperature, potential vorticity, and wind field data at multiple heights. For these variables, we used the European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-interim) dataset (Dee et al., 2011). For air temperature and wind speed, values were obtained at 12 pressure levels from the upper to lower stratosphere (5, 7, 10, 20, 30, 50, 70, 100, 125, 150, 175, and 200 hPa). Since the potential vorticity is a dynamical quantity that is conserved for adiabatic motions on isentropic surfaces, we used the potential vorticity obtained at 12 potential temperature levels from lower to the upper stratosphere (300, 315, 330, 350, 370, 395, 430, 475, 530, 600, 700, and 850 K). All data used in these analyses were daily mean values.
Despite consistent long-term trends observed at all 5 stations, Fig. 3 shows that the year-to-year variation changes considerably from station to station, similar to inter-annual variability observed at different station measurements (Grytsai et al., 2005; Huck et al., 2005). This observation means that the pattern of ozone depletion is spatially heterogeneous. We investigated whether the relationship of TOC among monitoring stations is consistent or not, based on the correlation analysis of TOCs. For this purpose, TOCs at the King Sejong station were compared with TOCs at other stations. The TOC values at King Sejong correlated well with the TOC values at Marambio (Fig. 4a) and Faraday (Fig. 4b). Both stations are located near the King Sejong station in the Antarctic peninsula (Fig. S4). As the distance between stations increases, however, the TOC correlation became weak, as shown in the case for the Halley (Fig. 4c) and Belgrano stations (Fig. 4d). Interestingly, these low correlations were enhanced during the austral springtime (September to November) as also shown in Fig. 4c and d. During this period, the TOCs at Halley and Belgrano (the high latitude region, > 70°S) were mostly below 220 Dobson Unit (DU), which is the threshold value for determining an ozone hole (Bodeker et al., 2002; Newman et al., 2004), while the King Sejong station was only partly affected by massive ozone depletion. The TOC values at the Halley (∼74°S) station were partially similar to the ozone levels at the King Sejong station (Fig. 4c), while most of the TOCs at Belgrano (∼79°S) station had values lower than 220 DU, resulting in the weak correlation with TOCs at the King Sejong station. This regional feature of stratospheric ozone depletion is related to the distinct atmospheric differences as the latitude increases. In other words, weak correlations of the TOCs between stations north and south
3. Ozone depletion properties in West Antarctica First, temporal variations of TOC at 5 stations around the Weddell Sea were examined from 1996 to 2015 (Fig. S1). It appears that both the ground- and satellite-based TOC values have recently shown a slight increasing trend. In particular, low TOCs increased and the annual variation decreased, implying that the ozone depletion has been weakened during the last decade. Monthly median and minimum patterns of TOC in austral spring better revealed the steady increase (Fig. 3). During the austral springtime, when the ozone hole typically forms, measurements at most stations also showed the recent recovery pattern more distinctly in September than that in October (Fig. S3). This feature also supports the recent discussion regarding the beginning of stratospheric ozone recovery (Solomon et al., 2016). Among the 5 research stations, the observed TOCs were generally the lowest at Belgrano and highest at the King Sejong station. 81
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Fig. 4. Comparison of TOCs at the King Sejong station to those at the (a) Marambio, (b) Faraday, (c) Halley, and (d) Belgrano stations. Different colors indicate each month. Dashed line shows the 220 DU, the threshold value for determining the occurrence of the ozone hole. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
strength of the Antarctic polar vortex (Fig. 5 and S7). Since the TOC pattern latitudinally differs in accordance with the edge of the polar vortex (Roscoe et al., 2012), the spatial or temporal properties of TOC generally tend to be investigated at different coordinates: equivalent latitudes accounting for the potential vorticity (Nash et al., 1996). Since the polar vortex difference effect is considered at equivalent latitudes, the TOC variation at this coordinate depends primarily on chemical ozone loss by halogens generated from chlorofluorocarbons. Thus, the analysis of TOC at equivalent latitudes is recommended to monitor the extent of polar ozone hole formation via halogen chemistry, as a number of previous studies have reported (e.g., Bodeker et al., 2002; Kuttippurath and Nair, 2017). However, the lesson in this section is that meteorological conditions substantially impact the regional differences of TOC patterns around West Antarctica. Additionally, the existence of polar vortex edge was discussed, which showed a different evolution pattern from the vortex core (Roscoe et al., 2012). In other words, TOC variation can be different among closely grouped ground-based stations even though they are inside the polar vortex; these observations indicate the importance of recognizing the dynamic effects of TOC variation. Also, TOC variation can be affected by many other atmospheric dynamics and climate effects (Thompson et al., 2011), making the diagnosis of stratospheric ozone recovery more difficult and trickier (Chipperfield et al., 2017). Therefore, it appears necessary to examine the TOC pattern at each region for determining how TOCs interact with the surrounding air
of 70°S indicate that meteorological conditions associated with the stratospheric ozone depletion are not ubiquitously situated around the Weddell Sea. To confirm this idea, we performed a correlation analysis among the 5 stations using meteorological factors in a manner similar to that of the TOC comparison in Fig. 4. Figs. S5 and S6 show correlation results of 50-hPa air temperature and 850-K potential vorticity from the closest stations (King Sejong vs. Marambio) to the farthest stations (King Sejong vs. Belgrano). As expected, the air temperature and the potential vorticity values between stations close to each other had a linear correlation (e.g., Figs. S5a and S6a), while correlations between distant stations were weak (e.g., Figs. S5d and S6d). Specifically, the Belgrano station had a much lower air temperature and stronger potential vorticity than that of the King Sejong station, and this difference was particularly large during the austral spring, the ozone hole season. Considering that ozone hole events occur inside the stratospheric polar vortex, this result illustrates that the TOC variation in the higher latitude region is more strongly influenced by the intensified polar vortex but that the TOC values in the lower latitudes are not as affected by the polar vortex. We found that the latitudinal difference of TOCs, stratospheric air temperature and potential vorticity can be very large around the Weddell Sea, particularly during the austral spring. As a result, the area of the polar vortex shifts among the five western Antarctic stations. Fig. 3 shows the large year-to-year TOC differences between 2010 (high TOC) and 2011 (low TOC) which also relates to the different size and 82
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Fig. 5. Spatial distribution of monthly mean potential vorticity at the 850-K height during September between 2010 (left) and 2011 (right).
Fig. 6. Vertical profile of correlations between the TOC and air temperature for 12 pressure heights (5, 7, 10, 20, 30, 50, 70, 100, 125, 150, 175, and 200 hPa) at the (a) King Sejong, (b) Marambio, (c) Faraday, (d) Halley and (e) Belgrano stations.
conditions. Therefore, we investigated the relationship between the TOCs and meteorological data associated with polar processing.
vertical profile of air temperature, potential vorticity and wind components obtained from the ERA-Interim reanalysis data. Correlations between meteorological factors and TOCs were calculated at each vertical altitude during each month from September to March, the austral spring and summer when the interaction between the stratospheric ozone and atmospheric circulation is expected (Thompson et al., 2011).
4. Relation to the meteorological conditions As discussed in Section 3, TOC variation is closely connected to polar vortex conditions. To better examine their relationship, we used a 83
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Fig. 7. Vertical profile of correlations between the TOC and potential vorticity for 12 potential temperature heights (300, 315, 330, 350, 370, 395, 430, 475, 530, 600, 700, and 850 K) at the (a) King Sejong, (b) Marambio, (c) Faraday, (d) Halley and (e) Belgrano stations.
2008). Previous studies based on the Chapman reactions showed that upper stratospheric ozone can be abundant at lower temperatures due to the slower ozone destruction (Jonsson et al., 2004; Shepherd and Jonsson, 2008). For example, Jonsson et al. (2004) found the negative temperature dependence of O + O2 + M → O3 + M reaction. This rationale has been frequently discussed in conjunction with the increase in greenhouse gases for their impact on the stratospheric ozone levels and temperature changes (e.g., Jonsson et al., 2009; Plummer et al., 2010; Gillett et al., 2011). Some satellite limb-sounding observations also clarified this anti-correlation between ozone and air temperature in the upper stratosphere (Stolarski et al., 2012). The vertically varying structure of correlations suggests that the variation of the TOC is not attributed to only a single atmospheric feature. While the massive stratospheric ozone loss in the strong polar vortex is typically dominant, the TOC variation also has some sensitivities to other factors, implying that the change in the ozone-temperature relationship is possible depending on atmospheric conditions. In fact, the vertical shape of ozone-temperature correlations shows large month-to-month variations (Fig. 6). In austral spring, the polar vortex is intensified, and large-scale ozone depletion begins. However, the onset date of ozone depletion can differ latitudinally due to regional solar intensity differences. Therefore, lower stratospheric positive correlations in September were only high at the King Sejong, Marambio and Faraday stations. Higher latitude stations (Halley and Belgrano) did not find meaningful correlations in September because the photochemical ozone loss is not active during this period. Station measurements had high positive correlations between ozone and temperature during October in the lower stratosphere. In mid to late October, however, stations < 70° started to exhibit negative correlations in the
Fig. 6 illustrates monthly correlation patterns between the TOC and stratospheric air temperature (from 200 to 5 hPa height) at each station. In general, a large contrast can be found vertically: high positive correlation in the lower stratosphere (> ∼50 hPa) but high negative correlation in the upper stratosphere (< ∼10 hPa). Positive correlations in the lower stratosphere were consistent during the austral spring and summer, but the negative correlation in the upper stratosphere indicated a larger seasonal difference. This pattern reveals the role of atmospheric conditions related to ozone chemistry between the upper and lower stratosphere. The positive correlation between ozone/temperature in the lower stratosphere indicates strong stratospheric ozone depletion in the intensified polar vortex. Previous studies have shown that air temperature becomes quite low in the intensified polar vortex because the meridional heat exchange is restricted. The polar stratospheric cloud (PSC), composed of ice particles, can be formed in the polar vortex. This PSC can take up nitric acid (HNO3) to inhibit the formation of chlorine nitrate (ClONO2), which is the reservoir species of chlorine radical (Keeble et al., 2014). Consequently, PSC diminishes the amount of stratospheric nitrogen, referred to as a denitrification process (Salawitch et al., 1989), and contributes to the recycling of the chlorine radical in the stratosphere, which results in strong ozone depletion. This process explains the positive correlation between air temperature and ozone as discussed in some previous studies (Solomon et al., 2005, 2014). The negative correlation between ozone and air temperature in the upper stratosphere can be explained by the temperature dependence of ozone chemistry. Stratospheric ozone production and loss processes are essentially explained by the Chapman mechanism (e.g., Velasco et al., 84
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Fig. 8. Vertical profile of correlations between the TOC and zonal wind speed (U wind) for 12 pressure heights (5, 7, 10, 20, 30, 50, 70, 100, 125, 150, 175, and 200 hPa) at the (a) King Sejong, (b) Marambio, (c) Faraday, (d) Halley and (e) Belgrano stations.
transported from other areas, perturbing the strength of polar vortex. In fact, previous studies (Pan et al., 2009; Gettelman et al., 2011) have discussed the occurrence of low ozone concentration in the lower stratosphere at polar regions and showed the associated meridional transport of mid-latitudinal tropospheric air into the polar stratosphere. Pan et al. (2009) also illustrated that this intrusion of mid-latitude tropospheric air masses containing lower ozone levels is attributed to the subtropical tropopause break; the core altitude of intrusion typically appears between 370 and 400 K potential temperature height. As shown in Fig. 7, the negative correlations between the TOC and potential temperature were also found below 400 K height. This negative correlation was higher at the King Sejong, Marambio and Faraday stations than it is at the Halley and Belgrano stations, which supports that the intrusion of mid-latitude tropospheric air masses weakens inside the polar vortex. One more interesting feature is the seasonal difference; negative correlation between ozone and potential vorticity was only distinct in the austral summer, the season after the stratospheric ozone hole formation. This pattern likely occurs because the poleward lowozone intrusion is more suitable when the polar vortex is not deeply intensified. Finally, we examined the relationship of TOC with zonal (Fig. 8) and meridional (Fig. 9) wind speeds, which can describe the influence of air-mass transport or mixing processes to TOC variations. Correlations with wind speed were not as strong as those with the air temperature (Fig. 6) and potential vorticity (Fig. 7), but some interesting features were still found. Between approximately 20 and 50 hPa height, we found rather high positive correlations during September at the King Sejong, Marambio and Faraday stations (Fig. 8a, b, and 8c) and during October at the Halley and Belgrano stations (Fig. 8d and e). Scatterplots between the TOC and zonal wind speed (Fig. S8) show that the strongly
upper stratosphere while stations > 70° did not. All five stations began to show high negative ozone-temperature correlations in the upper stratosphere in November. This negative correlation continued until December and weakened during the austral summer due to warmer temperatures (Fig. S5) which do not contribute to the ozone production in the upper stratosphere. In contrast to the upper stratosphere, the lower stratosphere had a consistent positive correlation through the austral spring and summer, implying the existence of a potential factor to retain the negative correlation between the TOC and air temperature. This seasonal variation of ozone-temperature correlations will be further discussed with continued analysis using other meteorological properties. In addition, we performed a similar correlation analysis using TOC and potential vorticity. Fig. 7 shows the vertical distribution of ozone and potential vorticity correlations following potential temperature height. Similar to the ozone and temperature correlations (Fig. 7), large contrast patterns were also found vertically: high positive correlation in the lower and middle stratosphere (> ∼400 K) but high negative correlations near the tropopause (< ∼400 K). High positive correlations in the lower and middle stratosphere clearly appear during the austral spring, with a monthly shift between lower and higher latitudes: September to November at the King Sejong, Marambio, and Faraday stations, and October to November at the Halley and Belgrano stations. The positive correlations become quite small during the austral summer, indicating that the weakened polar vortex merely affects the stratospheric ozone depletion. Meanwhile, contrasting negative correlations were found near the tropopause, meaning that the TOC decreases as the polar vortex weakens, implying the existence of mixing process. This feature may indicate that air masses having lower ozone concentrations can be 85
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Fig. 9. Vertical profile of correlations between the TOC and meridional wind speed (V wind) for 12 pressure heights (5, 7, 10, 20, 30, 50, 70, 100, 125, 150, 175, and 200 hPa) at the (a) King Sejong, (b) Marambio, (c) Faraday, (d) Halley and (e) Belgrano stations.
processes combine to vary the TOCs measured around the Weddell Sea, West Antarctica. In brief, the extent of halogen-related ozone loss in the lower and middle stratosphere is generally controlled by the strength of the polar vortex. In the upper stratosphere, the basic Chapman mechanism better explains ozone concentration as a function of temperature dependence. Near the tropopause, we found the impact from the meridional intrusion of mid-latitudinal tropospheric air masses had lower ozone concentrations than those of the stratospheric air masses. Correlations with the wind field provided some ideas for how the transport or mixing of Antarctic air masses affect the regional difference of TOC variation around the Weddell Sea. Each factor had a different spatial scale and seasonal impact, which resulted in the generally consistent but regionally distinguishing relationship to the TOC in West Antarctica. As widely known, stratospheric ozone in the Southern Hemisphere has been significantly examined in terms of the feedback with the climate variability and large-scale circulation. Considering the sensitivity of western Antarctic atmosphere to climate change (Turner et al., 2005; Ding et al., 2011), a more thorough investigation of western Antarctic ozone patterns will be required. Based on results from this study, the TOC in West Antarctica can change by several atmospheric patterns: halogen-related chemical loss in the polar vortex, the Chapman mechanism in the upper stratosphere, stratosphere-troposphere exchange between polar and mid-latitude regions, and meridional air-mass mixing. The complex interconnection and feedback processes among various southern hemispheric patterns should be discussed further with incorporating TOC properties in West Antarctica. Therefore, it appears that acquired data from long-term TOC observations will be beneficial to the future climate research for Antarctica and the Southern Hemisphere, which highlights the importance of continuous ozone
depleted TOC with weak zonal wind speeds can lead to positive correlations. This pattern likely appears because the halogen-related chemical loss of stratospheric ozone in the vortex increases in the absence of mixing with outside air masses. We also realized that correlations between the TOC and zonal wind speed also adequately detect the period having the largest decrease in stratospheric ozone, considering that median TOC values are actually the lowest in September at stations < 70° and in October at stations > 70° (Fig. 3). From the correlation between the TOC and meridional wind speed (Fig. 9), summertime (January to March) negative correlations from 20 to 50 hPa height was the most prominent pattern, particularly at the stations < 70°. Scatterplots between the TOC and meridional wind speed (Fig. S9) illustrated that this negative correlation indicates a high ozone supply with the poleward wind (i.e., negative meridional wind speed) and low ozone intrusion with the equatorward wind (i.e., positive meridional wind speed). This pattern appears to be reasonable considering that the TOC is usually lower near the South Pole than the ozone-rich conditions in the mid- and lower latitudes. In Fig. 6, we showed that the ozone-temperature correlation in the lower stratosphere is still positive during austral summer when the polar vortex is weakened. This pattern can be explained by the negative summertime correlation between the TOC and meridional wind speed because the ozone-rich air masses in the mid-latitude are warmer than the polar ozone-poor air masses. It can be presumed that the meridional air mixing can be activated after breaking the polar vortex; summertime high negative correlations between TOC and meridional wind in the stratosphere are also expected. Further investigation will be necessary to explain why the highest correlation with meridional wind appears in February. Based on these analyses, we found that multiple atmospheric 86
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monitoring.
Chipperfield, M.P., Bekki, S., Dhomse, S., Harris, N.R.P., Hassler, B., Hossaini, R., Steinbrecht, W., Thiéblemont, R., Weber, M., 2017. Detecting recovery of the stratospheric ozone layer. Nature 549, 211–218. https://doi.org/10.1038/nature23681. Dee, D.P., Uppala, S.M., Simmons, A.J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M.A., Balsamo, G., Bauer, P., Bechtold, P., Beljaars, A.C.M., van de Berg, L., Bidlot, J., Bormann, N., Delsol, C., Dragani, R., Fuentes, M., Geer, A.J., Haimberger, L., Healy, S.B., Hersbach, H., Hólm, E.V., Isaksen, L., Kållberg, P., Köhler, M., Matricardi, M., McNally, A.P., Monge-Sanz, B.M., Morcrette, J.-J., Park, B.-K., Peubey, C., de Rosnay, P., Tavolato, C., Thépaut, J.-N., Vitart, F., 2011. The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Q. J. Roy. Meteorol. Soc. 137, 553–597. Ding, Q., Steig, E.J., Battisti, D.S., Küttel, M., 2011. Winter warming in west Antarctica caused by central tropical Pacific warming. Nat. Geosci. 4, 398–403. https://doi.org/ 10.1038/NGEO1129. Farman, J.C., Gardiner, B.G., Shanklin, J.D., 1985. Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction. Nature 315, 207–210. Gettelman, A., Hoor, P., Pan, L.L., Randel, WlJ., Hegglin, M.I., Birner, T., 2011. The extratropical upper troposphere and lower stratosphere. Rev. Geophys. 49, RG3003. https://doi.org/10.1029/2011RG000355. Gillett, N.P., Akiyoshi, H., Bekki, S., Braesicke, P., Eyring, V., Garcia, R., Karpechko, A.Y., McLinden, C.A., Morgenstern, O., Plummer, D.A., Pyle, J.A., Rozanov, E., Scinocca, J., Shibata, K., 2011. Attribution of observed changes in stratospheric ozone and temperature. Atmos. Chem. Phys. 11, 599–609. https://doi.org/10.5194/acp-11-5992011. Grytsai, A., Grytsai, Z., Evtushevsky, A., Milinevsky, G., 2005. Interannual variability of planetary waves in the ozone layer at 65°S. Int. J. Rem. Sens. 26, 3377–3387. https:// doi.org/10.1080/01431160500076350. Hegglin, M.I., Shepherd, T.G., 2009. Large climate-induced changes in ultraviolet index and stratosphere-to-troposphere ozone flux. Nat. Geosci. 2, 687–691. https://doi.org/ 10.1038/ngeo604. Hoppel, K., Bevilacqua, R., Allen, D., Nedoluha, G., Randall, C., 2003. POAM III observations of the anomalous 2002 Antarctic ozone hole. Geophys. Res. Lett. 30, 1394. https://doi.org/10.1029/2003GL016899. Huck, P.E., McDonald, A.J., Bodeker, G.E., Struthers, H., 2005. Interannual variability in Antarctic ozone depletion controlled by planetary waves and polar temperature. Geophys. Res. Lett. 32, L13819. https://doi.org/10.1029/2005GL022943. Jonsson, A.I., de Grandpre, J., Fomichev, V.I., McConnell, J.C., Beagley, S.R., 2004. Doubled CO2-induced cooling in the middle atmosphere: photochemical analysis of the ozone radiative feedback. J. Geophys. Res. 109, D24103. https://doi.org/10. 1029/2004JD005093. Jonsson, A.I., Fomichev, V.I., Shepherd, T.G., 2009. The effect of nonlinearity in CO2 heating rates on the attribution of stratospheric ozone and temperature changes. Atmos. Chem. Phys. 9, 8447–8452. Kang, S.M., Polvani, L.M., Fyfe, J.C., Sigmond, M., 2011. Impact of polar ozone depletion on subtropical precipitation. Science 332, 951–954. https://doi.org/10.1126/ science.1202131. Keeble, J., Braesicke, P., Abraham, N.L., Roscoe, H.K., Pyle, J.A., 2014. The impact of polar stratospheric ozone loss on Southern Hemisphere stratospheric circulation and climate. Atmos. Chem. Phys. 14, 13705–13717. https://doi.org/10.5194/acp-1413705-2014. Kidston, J., Scaife, A.A., Hardiman, S.C., Mitchell, D.M., Butchart, N., Baldwin, M.P., Gray, L.J., 2015. Stratospheric influence on tropospheric jet streams, storm tracks and surface weather. Nat. Geosci. 8, 433–440. https://doi.org/10.1038/NGEO2424. Kondragunta, S., Flynn, L.E., Neuendorffer, A., Miller, A.J., Long, C., Nagataki, R., Zhou, S., Beck, T., Beach, E., McPeters, R., Stolarski, R., Bhartia, P.K., DeLand, M.T., Huang, L.-K., 2005. Vertical structure of the anomalous 2002 Antarctic ozone hole. J. Atmos. Sci. 62, 801–811. Konopka, P., Grooβ, J.-U., Hoppel, K.W., Steinhorst, H.-M., Müller, R., 2005. Mixing and chemical ozone loss during and after the Antarctic polar vortex major warming in September 2002. J. Atmos. Sci. 62, 848–859. Kroon, M., Petropavlovskikh, I., Shetter, R., Hall, S., Ulimann, K., Veefkind, J.P., McPeters, R.D., Browell, E.V., Levelt, P.F., 2008. OMI total ozone column validation with Aura-AVE CAFS observations. J. Geophys. Res. Atmos. 113, D15S13. https:// doi.org/10.1029/2007JD008795. Krueger, A.J., 1989. The global distribution of total ozone: TOMS satellite measurements. Planet. Space Sci. 37, 1555–1565. Kuttippurath, J., Nair, P.J., 2017. The signs of Antarctic ozone hole recovery. Sci. Rep. 7, 585. https://doi.org/10.1038/s41598-017-00722-7. Kuttippurath, J., Goutail, F., Pommereau, J.-P., Lefevre, F., Roscoe, H.K., Pazmino, A., Feng, W., Chipperfield, M.P., Godin-Beekmann, S., 2010. Estimation of Antarctic ozone loss from ground-based total column measurements. Atmos. Chem. Phys. 10, 6569–6581. Kuttippurath, J., Lefevre, F., Pommereau, J.-P., Roscoe, H.K., Goutali, F., Pazmino, A., Shanklin, J.D., 2013. Antarctic ozone loss in 1979-2010: first sign of ozone recovery. Atmos. Chem. Phys. 13, 1625–1635. Kuttippurath, J., Kumar, P., Nair, P.J., Chakraborty, A., 2018. Accuracy of satellite measurements in polar vortex conditions: comparisons with ground-based measurements. Remote Sens. Environ. 209, 648–659. https://doi.org/10.1016/j.rse.2018.02. 054. Manatsa, D., Morioka, Y., Behera, S.K., Yamagata, T., Matarira, C.H., 2013. Link between Antarctic ozone depletion and summer warming over southern Africa. Nat. Geosci. 6, 934–939. https://doi.org/10.1038/NGEO1968. Marchand, M., Bekki, S., Pazmino, A., Lefévre, F., Godin-Beekmann, S., Hauchecorne, A., 2005. Model simulations of the impact of the 2002 Antarctic ozone hole on the midlatitudes. J. Atmos. Sci. 62, 871–884. McLandress, C., Shepherd, T.G., Scinocca, J.F., Plummer, D.A., Sigmond, M., Jonsson,
5. Summary and conclusion This study investigated the properties of western Antarctic TOC levels using ground-based and satellite measurements near the Weddell Sea. On average, satellite gridded TOCs showed high correlation with the ground-based measured TOCs (R = ∼0.96) with MBE less than 7 DU. Additionally, the connection of spatiotemporal TOC variation to the ambient air conditions were examined using an auxiliary meteorological dataset. Validated TOCs around the Weddell Sea revealed the positive trend in the austral spring. However, there were some regional differences of TOC variations among stations because the border of the polar vortex oscillates over this area. Correlation analyses using several meteorological factors provided a number of interesting characteristics showing how the TOC increases or decreases according to the air conditions. Correlations with the air temperature (maximumly R > 0.9 at ∼50–100 hPa height, and minimum R < −0.8 at ∼5–10 hPa height) primarily indicated the activity of stratospheric chemical ozone depletion or formation. Correlations with the potential vorticity (maximumly R > 0.9 at ∼500–600 K height, and minimum R < −0.6 at ∼300–350 K height) and the wind field (R = ∼0.6 at maximum) depicted the influence of the polar vortex or the effect of meridional mixing on TOC variation. The variation of western Antarctic TOC was temporally (seasonally) and spatially (latitudinally or vertically) different. Thus, we suggest that TOC analysis can provide a number of useful tips for better understanding of Antarctic atmospheric patterns. Considering many unknowns regarding the connection between TOC variation and climate patterns, the ground- and satellite-based monitoring of Antarctic TOC levels should be maintained in the future. Long-term TOC measurements at the King Sejong station, first reported in this study, will be continued as one of efforts for contributing to the global monitoring network. Acknowledgements This study was supported by the Korea Polar Research Institute (KOPRI, PE17010) and the Korea Meteorological Administration Research and Development Program (KMIPA 2015-5170). Appendix A. Supplementary data Supplementary data to this article can be found online at https:// doi.org/10.1016/j.atmosenv.2018.09.056. References Bais, A.F., Lucas, R.M., Bornman, J.F., Williamson, C.E., Sulzberger, B., Austin, A.T., Wilson, S.R., Andrady, A.L., Bernhard, G., McKenzie, R.L., Aucamp, P.J., Madronich, S., Neale, R.E., Yazar, S., Young, A.R., de Gruijl, F.R., Norval, M., Takizawa, Y., Barnes, P.W., Robson, T.M., Robinson, S.A., Ballaré, C.L., Flint, S.D., Neale, P.J., Hylander, S., Rose, K.C., Wängberg, S.-Å., Häder, D.-P., Worrest, R.C., Zepp, R.G., Paul, N.D., Cory, R.M., Solomon, K.R., Longstreth, J., Pandey, K.K., Redhwi, H.H., Torikai, A., Heikkilä, A.M., 2018. Environmental effects of ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2017. Photochem. Photobiol. Sci. 17, 127–179. Balis, D., Kroon, M., Koukouli, M.E., Brinksma, E.J., Labow, G., Veefkind, J.P., McPeters, R.D., 2007. Validation of Ozone Monitoring Instrument total ozone column measurements using Brewer and Dobson spectrophotometer ground-based observations. J. Geophys. Res. 112, D24S46. https://doi.org/10.1029/2007JD008796. Bodeker, G.E., Struthers, H., Connor, B.J., 2002. Dynamical containment of Antarctic ozone depletion. Geophys. Res. Lett. 29, 1098. https://doi.org/10.1029/ 2001GL014206. Bramstedt, K., Gleason, J., Loyola, D., Thomas, W., Bracher, A., Weber, M., Burrows, J.P., 2003. Comparison of total ozone from the satellite instruments GOME and TOMS with measurements from the Dobson network 1996-2000. Atmos. Chem. Phys. 3, 1409–1419. Burrows, J.P., Weber, M., Buchwitz, M., Rozanov, V., Ladstätter-Weiβenmayer, A., Richter, A., DeBeek, R., Hoogen, R., Bramstedt, K., Eichmann, K.-U., Eisinger, M., 1999. The global ozone monitoring experiment (GOME): mission concept and first scientific results. J. Atmos. Sci. 56, 151–175.
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Atmospheric Environment 195 (2018) 78–88
J.-H. Koo et al.
Son, S.-W., Tandon, N.F., Polvani, L.M., Waugh, D.W., 2009. Ozone hole and southern hemisphere climate change. Geophys. Res. Lett. 36, L15705. Son, S.-W., Gerber, E.P., Perlwitz, J., Polvani, L.M., Gillett, N.P., Seo, K.‐H., Eyring, V., Shepherd, T.G., Waugh, D., Akiyoshi, H., Austin, J., Baumgaertner, A., Bekki, S., Braesicke, P., Bruhl, C., Butchart, N., Chipperfield, M.P., Cugnet, D., Dameris, M., Dhomse, S., Frith, S., Garny, H., Garcia, R., Hardiman, S.C., Jockel, P., Lamarque, J.F., Mancini, E., Marchand, M., Michou, M., Nakamura, T., Morgenstern, O., Pitari, G., Plummer, D.A., Pyle, J., Rozanov, E., Scinocca, J.F., Shibata, K., Smale, D., Teyssedre, H., Tian, W., Yamashita, Y., 2010. Impact of stratospheric ozone on Southern Hemisphere circulation change: a multimodel assessment. J. Geophys. Res. 115, D00M07. Steig, E.J., Schneider, D.P., Rutherford, S.D., Mann, M.E., Comiso, J.C., Shindell, D.T., 2009. Warming of the Antarctic ice-sheet surface since the 1957 international geophysical year. Nature 457, 459–462. https://doi.org/10.1038/nature07669. Stolarski, R.S., Douglass, A.R., Remsberg, E.E., Livesey, N.J., Gille, J.C., 2012. Ozone temperature correlations in the upper stratosphere as a measure of chlorine content. J. Geophys. Res. 117, D10305. https://doi.org/10.1029/2012JD017456. Thompson, D.W.J., Solomon, S., 2002. Interpretation of recent Southern Hemisphere climate change. Science 296, 895–899. Thompson, D.W.J., Baldwin, M.P., Solomon, S., 2005. Stratosphere–troposphere coupling in the southern hemisphere. J. Atmos. Sci. 62, 708–715. Thompson, D.W.J., Solomon, S., Kushner, P.J., England, M.H., Grise, K.M., Karoly, D.J., 2011. Signatures of the Antarctic ozone hole in Southern Hemisphere surface climate change. Nat. Geosci. 4, 741–749. Turner, J., Colwell, S.R., Marchall, G.J., Lachlan-cope, T.A., Carleton, A.M., Jones, P.D., Lagun, V., Reid, P.A., Iagovkina, S., 2005. Antarctic climate change during the last 50 years. Int. J. Climatol. 25, 279–294. https://doi.org/10.1002/joc.1130. Velasco, R.M., Uribe, F.J., Pérez-Chavela, E., 2008. Stratospheric ozone dynamics according to the Chapman mechanism. J. Math. Chem. 44, 529–539. https://doi.org/ 10.1007/s10910-007-9326-7. Waugh, D.W., Oman, L., Kawa, S.R., Stolarski, R.S., Pawson, S., Douglass, A.R., Newman, P.A., Nielsen, J.E., 2009. Impacts of climate change on stratospheric ozone recovery. Geophys. Res. Lett. 36, L03805. https://doi.org/10.1029/2008GL036223. Yang, X.-Y., Huang, R.X., Wang, D.X., 2007. Decadal changes of wind stress over the Southern Ocean associated with Antarctic ozone depletion. J. Clim. 20, 3395–3410. Yang, E.-S., Cunnold, D.M., Newchurch, M.J., Salawitch, R.J., McCormick, M.P., Russell III, J.M., Zawodny, J.M., Oltmans, S.J., 2008. First stage of Antarctic ozone recovery. J. Geophys. Res. 113, D20308. https://doi.org/10.1029/2007JD009675. Zhang, Y., Li, J., Zhou, L., 2017. The relationship between polar vortex and ozone depletion in the Antarctic stratosphere during the period 1979-2016. Adv. Meteorol. 2017, 3078079. https://doi.org/10.1155/2017/3078079.
A.I., Reader, M.C., 2011. Separating the dynamical effects of climate change and ozone depletion. Part II: southern Hemisphere troposphere. J. Clim. 24, 1850–1868. Miyagawa, K., Petropavlovskikh, I., Evans, R.D., Long, C., Wild, J., Manney, G.L., Daffer, W.H., 2014. Long-term changes in the upper stratospheric ozone at Syowa, Antarctica. Atmos. Chem. Phys. 14, 3945–3968. https://doi.org/10.5194/acp-143945-2014. Nash, E.R., Newman, P.A., Rosenfield, J.E., Schoeberl, M.R., 1996. An objective determination of the polar vortex using Ertel's potential vorticity. J. Geophys. Res. 101, 9471–9478. Newman, P.A., Kawa, S.R., Nash, E.R., 2004. On the size of the Antarctic ozone hole. Geophys. Res. Lett. 31, L21104. https://doi.org/10.1029/2004GL020596. Pan, L.L., Randel, W.J., Gille, J.C., Hall, W.D., Nardi, B., Massie, S., Yudin, V., Khosravi, R., Konopka, P., Tarasick, D., 2009. Tropospheric intrusions associated with the secondary tropopause. J. Geophys. Res. 114, D10302. https://doi.org/10.1029/ 2008JD011374. Perlwitz, J., Pawson, S., Fogt, R.L., Nielsen, J.E., Neff, W.D., 2008. Impact of stratospheric ozone hole recovery on Antarctic climate. Geophys. Res. Lett. 35, L08714. https:// doi.org/10.1029/2008GL033317. Plummer, D.A., Scinocca, J.F., Shepherd, T.G., Raeder, M.C., Jonsson, A.I., 2010. Quantifying the contributions to stratospheric ozone changes from ozone depleting substances and greenhouse gases. Atmos. Chem. Phys. 10, 8803–8820. https://doi. org/10.5194/acp-10-8803-2010. Roscoe, H.K., Feng, W., Chipperfield, M.P., Trainic, M., Shuckburgh, E.F., 2012. The existence of the edge region of the Antarctic stratospheric vortex. J. Geophys. Res. 117, D04301. https://doi.org/10.1029/2011JD015940. Salawitch, R.J., Gobbi, G.P., Wofsy, S.C., McElroy, M.B., 1989. Denitrification in the Antarctic stratosphere. Nature 339, 525–527. Salby, M., Titova, E., Deschamps, L., 2011. Rebound of Antarctic ozone. Geophys. Res. Lett. 38, L09702. https://doi.org/10.1029/2011GL047266. Shepherd, T.G., 2008. Dynamics, stratospheric ozone, and climate change. Atmos.-Ocean 46, 117–138. https://doi.org/10.3137/ao.460106. Shepherd, T.G., Jonsson, A.I., 2008. On the attribution of stratospheric ozone and temperature changes to changes in ozone-depleting substances and well-mixed greenhouse gases. Atmos. Chem. Phys. 8, 1435–1444. Solomon, S., Portmann, R.W., Sasaki, T., Hofmann, D.J., Thompson, D.W.J., 2005. Four decades of ozonesonde measurements over Antarctica. J. Geophys. Res. 110, D21311. https://doi.org/10.1029/2005JD005917. Solomon, S., Haskins, J., Ivy, D.J., Min, F., 2014. Fundamental differences between Arctic and Antarctic ozone depletion. Proc. Natl. Acad. Sci. U.S.A. 111, 6220–6225. Solomon, S., Ivy, D.J., Kinnison, D., Mills, M.J., Neely III, R.R., Schmidt, A., 2016. Emergence of healing in the Antarctic ozone layer. Science 353, 269–274.
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