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Peer review report 2 On “Mapping daily evapotranspiration at field scales over rainfed and irrigated agricultural areas using remote sensing data fusion”
Agricultural and Forest Meteorology 201 (2015) 312–313
Contents lists available at ScienceDirect
Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet
Peer review report
Peer review report 2 On “Mapping daily evapotranspiration at field scales over rainfed and irrigated agricultural areas using remote sensing data fusion”
Original Submission Recommendation Minor Revision Comments to Author (1) Lines 71-78 state that there have been a number of successful applications of ALEXI and DisALEXI since 2003. Has anything actually changed in these approaches since the original Anderson et al. (1997) and Norman et al. (2003) studies? What precisely were the shortcomings or deficiencies observed when these methods were used with several different data sources? (2) Clearly state the differences between the Camilleri et al. (2012, 2013) papers and the current manuscript. I also assume that the fusion method is fully described in Gao et al. (2006). Are the authors aware of any other fusion approaches? (3) The brief description of STARFM in Section 2.2 (with Figure 4) is not clear and needs to be revisited. There is a reference for further details to Cammalleri et al. (2013) but that is still under review and not yet available! How are the ALEXI maps used as common normalization fields for both DisAlexi applications? (see lines 217 and 218). In Lines 220-228 there is an explanation of how to estimate (at Landsat resolution) ET from MODIS data for a given day (d) which lies somewhere between two actual Landsat overpasses. (Note that Figure (1) should illustrate that we have far fewer Landsat scenes (viz. 5 at BUSH and 6 at MEAD than MODIS scenes). It is clear that the number of pixels in the window (w,w) is determined by the resolution of the Landsat scene. Lines 230-237 then explain how the Landsat scene to be used in the fusion is found to be the one on day (d0) which has the highest correlation with the MODIS scene on day (d). The Landsat/MODIS pair on day d0 is therefore selected for further use with the MODIS scene on day (d). The use of Equation (4) and the derivation of the weighting factor Wij however are not easily understood. How is Wij parameterized? (4) The discussion in lines 434-448 points to problems with isolated irrigation events, intermittent cloud, small field sizes as well as the role of advection. Yet, in the cumulative ET plots of Figure 5 and the monthly maps of Figure 6 these problems are somehow played down. (5) The Conclusions to the paper, especially lines 529-530, indicate that the methodology described in this paper has potential for
DOI of original article: http://dx.doi.org/10.1016/j.agrformet.2013.11.001. 0168-1923/$ – see front matter http://dx.doi.org/10.1016/j.agrformet.2015.08.122
generating daily ET maps across agricultural landscapes. Unfortunately there is little discussion of the obstacles ahead and of the type of work needed to improve such estimates. (6) This is not a review paper. There are far too many references (ca. 50). Are they all needed? (7) Standardise hyphenation throughout the m/s: e.g line 63 large area or large-area? line 91: large scale, mid range? Line 109: end-product, line 112: coarse-scale; etc etc. . . Minor comments (typos, editorial) by line number 32: Bushland TX and Mead NE 34: Rephrase “when provided” 40: Rephrase “such that” 43: “in this case”? 54: approximately 67: “available energy between turbulent fluxes of sensible and latent heat, the latter of which.” 85: principal 105: the fusion methodology has already been described elsewhere so it is applied here 118: effectively? 119: evaluate the ability 133: these parsimonious systems ate not considered here 136: to be described 159: Rn identifies 177: Latent heat from the canopy 204: greater spatial resolution 218: for both? DisALEXI applications. Which ones? 232: meteorological 234: (among all the available Landsat/MODIS pairs at Landsat overpass times) 247: fine-scale 263/267: a bit more information on the location (and height) of the flux measurements is needed 269: what is a continuous corn production system? 280: still? Significant 299/300: this reads as if there were 6 locations but you use 3 locations on 5 days for BUSH in Table 1 and Figure 3 (a) 312/313: what is meant with “addressing the effects of heat and watervapor density” 328: More specifically 353: native? 365: “ET streamflow” does not make sense. You mean “accumulated ET” or “seasonal water use”? 370: This? 402: irrigation events at MEAD are not indicated. Why not?
Peer review report / Agricultural and Forest Meteorology 201 (2015) 312–313
407: according to line 301 lysimeter data were not going to be used. Why not? 419: MBE has not yet been defined. 425: you mean “reasonably well”? 439: “likely to be limited to” 451: explain the use of reference ET0 in Figure 5 456: “in a semi-arid climate” 466: define “scene” 478: “likely”? 507: “were correctly identified” 518/519: explain “underestimation of daily ET due to underestimation of ET by the model” 521: at the BEAREX08 site at Bushland TX 523: “after irrigation events”
313
524: “rainfed” not “rained” 527-530: rephrase the last two sentences Ross, J. (1975) reference: Academic Press List of Figures: Figure 1, line 2: on the prediction date (d);line 3: “and all the available Landsat scenes to detect the . . .” Figure 4 Why no indication of the irrigation events in panel (d)?. Figure 6 Are the two maps equal to the two “scenes”?. Table 1: BUSH (5 days) and MEAD (6days) Table 2 RB is not used in Table 2 Anonymous
Contents lists available at ScienceDirect
Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet
Peer review report
Peer review report 2 On “Mapping daily evapotranspiration at field scales over rainfed and irrigated agricultural areas using remote sensing data fusion”
Original Submission Recommendation Minor Revision Comments to Author (1) Lines 71-78 state that there have been a number of successful applications of ALEXI and DisALEXI since 2003. Has anything actually changed in these approaches since the original Anderson et al. (1997) and Norman et al. (2003) studies? What precisely were the shortcomings or deficiencies observed when these methods were used with several different data sources? (2) Clearly state the differences between the Camilleri et al. (2012, 2013) papers and the current manuscript. I also assume that the fusion method is fully described in Gao et al. (2006). Are the authors aware of any other fusion approaches? (3) The brief description of STARFM in Section 2.2 (with Figure 4) is not clear and needs to be revisited. There is a reference for further details to Cammalleri et al. (2013) but that is still under review and not yet available! How are the ALEXI maps used as common normalization fields for both DisAlexi applications? (see lines 217 and 218). In Lines 220-228 there is an explanation of how to estimate (at Landsat resolution) ET from MODIS data for a given day (d) which lies somewhere between two actual Landsat overpasses. (Note that Figure (1) should illustrate that we have far fewer Landsat scenes (viz. 5 at BUSH and 6 at MEAD than MODIS scenes). It is clear that the number of pixels in the window (w,w) is determined by the resolution of the Landsat scene. Lines 230-237 then explain how the Landsat scene to be used in the fusion is found to be the one on day (d0) which has the highest correlation with the MODIS scene on day (d). The Landsat/MODIS pair on day d0 is therefore selected for further use with the MODIS scene on day (d). The use of Equation (4) and the derivation of the weighting factor Wij however are not easily understood. How is Wij parameterized? (4) The discussion in lines 434-448 points to problems with isolated irrigation events, intermittent cloud, small field sizes as well as the role of advection. Yet, in the cumulative ET plots of Figure 5 and the monthly maps of Figure 6 these problems are somehow played down. (5) The Conclusions to the paper, especially lines 529-530, indicate that the methodology described in this paper has potential for
DOI of original article: http://dx.doi.org/10.1016/j.agrformet.2013.11.001. 0168-1923/$ – see front matter http://dx.doi.org/10.1016/j.agrformet.2015.08.122
generating daily ET maps across agricultural landscapes. Unfortunately there is little discussion of the obstacles ahead and of the type of work needed to improve such estimates. (6) This is not a review paper. There are far too many references (ca. 50). Are they all needed? (7) Standardise hyphenation throughout the m/s: e.g line 63 large area or large-area? line 91: large scale, mid range? Line 109: end-product, line 112: coarse-scale; etc etc. . . Minor comments (typos, editorial) by line number 32: Bushland TX and Mead NE 34: Rephrase “when provided” 40: Rephrase “such that” 43: “in this case”? 54: approximately 67: “available energy between turbulent fluxes of sensible and latent heat, the latter of which.” 85: principal 105: the fusion methodology has already been described elsewhere so it is applied here 118: effectively? 119: evaluate the ability 133: these parsimonious systems ate not considered here 136: to be described 159: Rn identifies 177: Latent heat from the canopy 204: greater spatial resolution 218: for both? DisALEXI applications. Which ones? 232: meteorological 234: (among all the available Landsat/MODIS pairs at Landsat overpass times) 247: fine-scale 263/267: a bit more information on the location (and height) of the flux measurements is needed 269: what is a continuous corn production system? 280: still? Significant 299/300: this reads as if there were 6 locations but you use 3 locations on 5 days for BUSH in Table 1 and Figure 3 (a) 312/313: what is meant with “addressing the effects of heat and watervapor density” 328: More specifically 353: native? 365: “ET streamflow” does not make sense. You mean “accumulated ET” or “seasonal water use”? 370: This? 402: irrigation events at MEAD are not indicated. Why not?
Peer review report / Agricultural and Forest Meteorology 201 (2015) 312–313
407: according to line 301 lysimeter data were not going to be used. Why not? 419: MBE has not yet been defined. 425: you mean “reasonably well”? 439: “likely to be limited to” 451: explain the use of reference ET0 in Figure 5 456: “in a semi-arid climate” 466: define “scene” 478: “likely”? 507: “were correctly identified” 518/519: explain “underestimation of daily ET due to underestimation of ET by the model” 521: at the BEAREX08 site at Bushland TX 523: “after irrigation events”
313
524: “rainfed” not “rained” 527-530: rephrase the last two sentences Ross, J. (1975) reference: Academic Press List of Figures: Figure 1, line 2: on the prediction date (d);line 3: “and all the available Landsat scenes to detect the . . .” Figure 4 Why no indication of the irrigation events in panel (d)?. Figure 6 Are the two maps equal to the two “scenes”?. Table 1: BUSH (5 days) and MEAD (6days) Table 2 RB is not used in Table 2 Anonymous