First global tropospheric maps show streams of tropospheric ozone crossing the oceans Aura Instruments : OMI & MLS OMI & MLS can estimate the tropospheric ozone residual by subtracting the MLS stratospheric ozone from OMI column ozone. High residual regions correspond to pollution sources and transport. The cartoon shows how tropospheric ozone residual (TOR) is computed by subtracting the stratospheric column ozone from the total column ozone. The stratospheric column ozone is computed using the MLS limb measurements of ozone. The total column O3 is measured by OMI, and the TOR is the difference between them.

The monthly mean maps of the TOR show pollution streaming from the U.S., Europe and China to the west in summer and pollution from biomass burning in the equatorial zone. Click image above to view large version