NESDIS Advanced-TOVS (ATOVS) Sounding Products

The National Oceanic and Atmospheric Administration (NOAA) successfully deployed the NOAA-15 satellite into polar orbit (ascending, evening) on May 13, 1998. NOAA-15 features the first in a series of next generation atmospheric sounders referred to as Advanced TIROS-N Operational Vertical Sounder (ATOVS). ATOVS is comprised of the 20-channel High-resolution Infrared Radiation Sounder (HIRS), the 15-channel Advanced Microwave Sounding Unit (AMSU-A), and 5-channel Advanced Very High Resolution Radiometer (AVHRR). The NOAA-15 suite of sounders also includes the 5-channel AMSU-B radiometer which provides high resolution moisture measurements. However, at this time the processing of AMSU-B products at the National Environmental Satellite Data and Information Service (NESDIS) is done independent of all other sensors.

NESDIS recently completed a successful scientific checkout of the ATOVS sounders and operational product generation systems. The validation exercise proceeded quite smoothly, leading to the successful implementation of NOAA-15 operational sounding products in March, 1999, well ahead of the initial estimates of 18 months (or more) from the launch date. The suite of operational sounding products include the radiometric measurements from the sounders, the derived temperature and moisture sounding profiles, and cloud products. Products are global, providing an average of two observations per day for most locations on the earth.

The following report provides the current status for each ATOVS sounder, the scientific algorithms for deriving the operational products, and the product accuracy. Results include comparisons against collocated radiosondes, numerical weather prediction forecasts, and sounding products from co-existing NOAA and Defense Meteorological Satellite Program (DMSP) polar satellite systems. A special set of results in conjunction with the Nauru99 tropical field experiment are also provided.