A comparison of thermal infrared and ultraviolet retrievals of SO2 in the cloud produced by the 2003 Al-Mishraq State sulfur plant fire

The detection of SO2 plumes by space-based sensors has been demonstrated in the UV and TIR. However, the relationship between these retrieval techniques is poorly constrained. In this paper we compare near-coincidental EP TOMS and MODIS data of a near-pure SO2 plume from the Al-Mishraq State sulfur plant fire on 29 June 2003. We resampled the MODIS data to the spatial resolution of EP TOMS in order to compare the two SO2 retrievals at the pixel scale. EP TOMS and MODIS return SO2 total tonnages of 103 and 118 kt, respectively. Overall, the agreement between the techniques on a pixel scale ranges between 10% to greater than 90% with no discernible spatial pattern. The variable agreement between the two retrievals is likely the result of differences in spatial resolution, presence of sulfates, and variations in plume height with distance from the fire. Citation: Kearney, C., I. M. Watson, G. J. S. Bluth, S. Carn, and V. J. Realmuto (2009), A comparison of thermal infrared and ultraviolet retrievals of SO2 in the cloud produced by the 2003 Al-Mishraq State sulfur plant fire, Geophys. Res. Lett., 36, L10807, doi: 10.1029/2009GL038215.