NASA Logo - National Aeronautics and Space Administration  
Welcome to The Tropospheric Ozone Residual (TOR) Project Homepage

In the late 1980s, Dr. Jack Fishman pioneered the use of satellite observations to provide a unique and eye-opening perspective of the extent of global pollution. This technique, called the tropospheric ozone residual, or TOR, determined the quasi-global extent of tropospheric ozone by subtracting the stratospheric column ozone from one satellite from the total column ozone determined from a different satellite. However, the original dataset utilizing TOMS and SAGE data was generally limited to climatological studies. After the application of an empirical correction applied to the much larger SBUV dataset (in terms of the number of available gridded profiles per day) and using daily total column satellite data, a global TOR dataset (from 50N to 50S), that greatly enhanced the regional aspects of air pollution, was constructed. This current dataset, which first utilized the TOMS instrument and then later the OMI instrument for the total column amount, is now available as monthly averages from 1979 to 2005. Following the creation of this monthly TOR climatology, several scientific studies utilizing the empirically corrected TOR technique were conducted and showed 1) strong relationships between the North Atlantic Oscillation and trans-Atlantic pollution transport, 2) an Arctic Oscillation-induced variability in satellite-derived tropospheric ozone, and 3) the interannual variability of stratospheric and tropospheric ozone. More recent investigations utilizing this technique were accomplished that analyzed the interannual relationship between surface observations of air pollution, crop yield, and the TOR over the Midwestern United States. Moving forward, the research focus will continue to be on utilizing the TOR for air quality applications, while also refining the TOR technique to extend it to present day using available satellite data and model output.

Recent Additions


Get Adobe Acrobat  ReaderThe PDF documents given above are best viewed in Adobe Acrobat® 4.0 or better.
Adobe Copyright Info: ©Adobe Systems Inc. All Rights Reserved.