SUSSKIND et al.: IMPROVED TEMPERATURE SOUNDING AND QUALITY CONTROL METHODOLOGY

This paper describes the Atmospheric Infrared Sounder (AIRS) Science Team Version 5 retrieval algorithm in terms of its three most significant improvements over the methodology used in the AIRS Science Team Version 4 retrieval algorithm: the use of AIRS clear column radiances in the entire 4.3-μm CO2 absorption band in the retrieval of temperature profiles T(p) during both day and night, with tropospheric sounding 15-μm CO2 observations being now used primarily in the generation of clear column radiances i for all channels; development of a new methodology to provide accurate case-bycase error estimates for retrieved geophysical parameters and for channel-by-channel clear column radiances and their use in a new approach for Quality Control; and an approach to provide AIRS soundings in partially cloudy conditions that does not require use of any microwave data. This new AIRS-only sounding methodology, referred to as AIRS Version 5 AO, was developed as a backup to AIRS Version 5 should the Advanced Microwave Sounding Unit (AMSU)-A instrument fail. Results are shown that compare the relative performance of the AIRS Version 4, Version 5, and Version 5 AO. Results using Version 5 retrievals in conjunction with different Quality Control thresholds are also shown for a recent period to demonstrate that empirical coefficients continue to be applicable in later time periods. The Goddard Data and Information Services Center (DISC) is now generating and distributing products derived using the AIRS Science Team Version 5 retrieval algorithm. This paper describes the Quality Control flags contained in the DISC AIRS/AMSU retrieval products and their intended use for scientific purposes.