Use of Radiosondes in NESDIS Advanced-TOVS (ATOVS) Soundings Products

The National Oceanic and Atmospheric Administration (NOAA) operates several sounding product generation systems in support of NOAA and Defense Meteorological Satellite Program (DMSP) polar orbiting satellites. The most recent of these was NOAA-15, which was launched in May 1998 and operationally implemented in April 1999. NOAA-15 features the new 20-channel Advanced TIROS Operational Vertical Sounder (ATOVS) instrument configuration.

The following report addresses the latest procedures for compiling radiosonde report data and collocation with NOAA-15 satellite observations, and their use in the derivation and validation of National Environmental Satellite Data and Information Service (NESDIS) operational sounding products.

The retrieval algorithms used by NESDIS to convert the radiometric measurements into temperature and moisture sounding products require the direct use of collocated radiosondes and satellite soundings. These collocations are compiled and updated daily, and are used to derive first guess information and coefficients for the retrieval solution. The following report describes the steps for selecting and screening the radiosonde reports, creating the collocations with the satellite data, and their subsequent use in the generation and evaluation of the satellite sounding products. Topics include the new "Unified" approach for compiling the radiosonde report data once for use in all NESDIS operational systems, improved quality control, report data interpolation and extrapolation techniques, and the routine availability of radiosonde and satellite collocation data sets.