Product

EP/TOMS NRT Data Quality Assessment

Most of the information previously available at this site has been moved to the public TOMS site . Descriptions of some of our on-going analysis and results are still provided here.

Some problems have been identified in the course of TOMS validation studies that are not well understood. We hope to develop a better understanding of these problems and add links to descriptions of our findings in the months to come. If you have comments or suggestions about these items or any additional items, please email to cgw@qhearts.gsfc.nasa.gov. The current list of items includes:

Cloud height errors - Variability in true cloud height about the climatological mean leads to errors in derived ozone. This error source is included in the table above, but in extreme conditions, higher errors can occur.
Over-estimation over Antarctica - Validation studies indicate that TOMS derived ozone is approximately 5% high relative ground-based measurements in the Antarctic.
Continental Ghosting - Some continental boundaries are apparent in long-term means of the TOMS ozone field. The aerosol contamination and high terrain discussions in the user's guide explain some of this phenomenon, but not all of it. The Red Sea seems to be an interesting region.
Scan angle dependence - The user's guide illustrates a background scan angle dependence in TOMS ozone of about 1%, and discusses sun glint over oceans and volcanic aerosol as sources of larger dependencies. The cause of the background scan angle dependence has not been determined.

Responsible NASA official & Web Team
Dr. P.K. Bhartia, TOMS Project Scientist & Charles Wellemeyer (Raytheon/ITSS)
Last revised: November 10, 1998