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Application of spectrum analysis to synoptic-pollution data
3-0
Discussions REFERE\CES
Dalager S. I 197-I) Sammrnligning af msroder til miling al‘ svakrsklv og swldioxid. Enviroplan. Copsnha.gen 1974. (In Danish.) Dnla8er S. (1975) Correlations between methods for measuring suspended paruculates in ambient air. -1r~1:0~pltrric E~~cironmrnr. fo be published. Hcrpertz E. i 1969) Ein einfaches Langzeitmessverfahren zur Bestimmung der Stsubkonzentration in der Bodennahen Atmosph%re(LIB verfahren). Staub 29,408-413. (In German.) F. 1. Smidth & Co. ;\ S and Enviroplan A,/S: Srzvestamilinpr. Valby 1973 Report to Storkabenhains Luftforureningsudvalg Copenhagen 1974. (In Danish.]
APPLICATION OF SPECTRUM SYNOPTIC-POLLUTION
ANALYSIS DATA
TO
The authors are to be commended for their clear and concise presentation. and one hopes thar this 7%da> study will be repeated in other seasons and in other years. I wonder if the two overlapping data blocks indicated seasonal trends. The dimensions of the ordinate of Fig. I should of course be squared. It is unfortunate that the areal and height distributions of sources of emission of the two pollutants studied were not described. There is some indication in the published results that suspended particuiares were largel! introduced at quite low heights above the surface and from widel! distributed places. whereas a significant portion of the sulfur dioxide was emitted at greater effective heights and from fewer places. If so the differences between the pollutants as regards their correiations with temperature difference and with wind speed can be explained. Also the phase ia8s of 180’ and 270” in Fig. 4. with the maximum of sulfur dioxide at the 60-ft level behind the maximum of wind speed at the ZOO-ft level. are consistent with such disparate source distributions. The presence of a shear destabilization process (Wanta. 1969 and 1974) on a time scale of several hours is juggested: more information about the source distributions might justif! other useful inferences.
* TILLEY M. A. and MCBEU
G. .A. (1973) Amosphrrir
Enrirorwettt
7. 793-601
REFERENCES IVanta R. C.( 1969) Local shear destabilization-A challenge to recognition and exploitation in geophysical Frocesses.J. yeophys. Res. 74, 55365339. \Vanta R. C. (1974) Ozone antagonist in the ambient air of northxiesrern metropolitan Washington .’ .-lr~~rosyii-~,-ic Eutirorvrrcrtt 8, 687-69 I.
AUTHOR’S
REPLY
The areal distribution of emission sources is described in a paper by Munn (1969) which was referenced in our paper. The main SO1 sources were power plants which would emit the pollution at an elevated level. The shear destabilization process suggested by Wanta coutd be a possible explanation for the 270’ phase la8 of SO: behind the wind speed at short periods. If wind speed and SOz were ISO’ out of phase at for example. 60 ft then the wind speed at XOft and SO? at 60 ft would be more than IS0 out of phase if the wind at 6Oft lagged the wind at 200 It as suggested by the shear destabilization process. However, the results on Fig 3 show that there is not an appreciable phase lag between the wind at 20 ft and that at 200 ft. The SO: analjxr and the wind tower were not co-located. being separated by about 3 miles in almost a north-south direction. This uould account for a further phase la8 for winds with a southerly component. Because the SO>--wind speed coherence is usually not statisticall) significant for periods less than I days. it will be ditTicult on these data to make further inferences on the correlations on periods of a few hours. .-ltmosplteric Encironrueru 4905 Du&rin Srreer. Dowrrsrie~~. Owrio M3 H 5 T-4. Canada
Serrict,.
M. A. T~LEI
Discussions REFERE\CES
Dalager S. I 197-I) Sammrnligning af msroder til miling al‘ svakrsklv og swldioxid. Enviroplan. Copsnha.gen 1974. (In Danish.) Dnla8er S. (1975) Correlations between methods for measuring suspended paruculates in ambient air. -1r~1:0~pltrric E~~cironmrnr. fo be published. Hcrpertz E. i 1969) Ein einfaches Langzeitmessverfahren zur Bestimmung der Stsubkonzentration in der Bodennahen Atmosph%re(LIB verfahren). Staub 29,408-413. (In German.) F. 1. Smidth & Co. ;\ S and Enviroplan A,/S: Srzvestamilinpr. Valby 1973 Report to Storkabenhains Luftforureningsudvalg Copenhagen 1974. (In Danish.]
APPLICATION OF SPECTRUM SYNOPTIC-POLLUTION
ANALYSIS DATA
TO
The authors are to be commended for their clear and concise presentation. and one hopes thar this 7%da> study will be repeated in other seasons and in other years. I wonder if the two overlapping data blocks indicated seasonal trends. The dimensions of the ordinate of Fig. I should of course be squared. It is unfortunate that the areal and height distributions of sources of emission of the two pollutants studied were not described. There is some indication in the published results that suspended particuiares were largel! introduced at quite low heights above the surface and from widel! distributed places. whereas a significant portion of the sulfur dioxide was emitted at greater effective heights and from fewer places. If so the differences between the pollutants as regards their correiations with temperature difference and with wind speed can be explained. Also the phase ia8s of 180’ and 270” in Fig. 4. with the maximum of sulfur dioxide at the 60-ft level behind the maximum of wind speed at the ZOO-ft level. are consistent with such disparate source distributions. The presence of a shear destabilization process (Wanta. 1969 and 1974) on a time scale of several hours is juggested: more information about the source distributions might justif! other useful inferences.
* TILLEY M. A. and MCBEU
G. .A. (1973) Amosphrrir
Enrirorwettt
7. 793-601
REFERENCES IVanta R. C.( 1969) Local shear destabilization-A challenge to recognition and exploitation in geophysical Frocesses.J. yeophys. Res. 74, 55365339. \Vanta R. C. (1974) Ozone antagonist in the ambient air of northxiesrern metropolitan Washington .’ .-lr~~rosyii-~,-ic Eutirorvrrcrtt 8, 687-69 I.
AUTHOR’S
REPLY
The areal distribution of emission sources is described in a paper by Munn (1969) which was referenced in our paper. The main SO1 sources were power plants which would emit the pollution at an elevated level. The shear destabilization process suggested by Wanta coutd be a possible explanation for the 270’ phase la8 of SO: behind the wind speed at short periods. If wind speed and SOz were ISO’ out of phase at for example. 60 ft then the wind speed at XOft and SO? at 60 ft would be more than IS0 out of phase if the wind at 6Oft lagged the wind at 200 It as suggested by the shear destabilization process. However, the results on Fig 3 show that there is not an appreciable phase lag between the wind at 20 ft and that at 200 ft. The SO: analjxr and the wind tower were not co-located. being separated by about 3 miles in almost a north-south direction. This uould account for a further phase la8 for winds with a southerly component. Because the SO>--wind speed coherence is usually not statisticall) significant for periods less than I days. it will be ditTicult on these data to make further inferences on the correlations on periods of a few hours. .-ltmosplteric Encironrueru 4905 Du&rin Srreer. Dowrrsrie~~. Owrio M3 H 5 T-4. Canada
Serrict,.
M. A. T~LEI