Calibration and Validation of Satellite Sensors at Noaa/nesdis/ora: Summary of Methods and Recent Results

Abstract

The NESDIS Office of Research and Applications performs sensor calibration and data product validation (cal/val) for NOAA’s polar and geosynchronous operational environmental satellites, as well as for a number of non-NOAA spacecraft and instruments. This paper summarizes the scope of these efforts, describes some of the unique methods developed and used by ORA and its partners, and presents and discusses selected recent results. Particular attention is paid to the Simultaneous Nadir Overpass (SNO) method for the on-orbit inter-calibration of like sensors on successive iterations of NOAA’s Polar-orbiting Operational Environmental Satellites. Developed to check the channel by channel performance of the High Resolution Infrared Sounder (HIRS) instruments on NOAA-17 and -18, the SNO method has now been applied to test the effectiveness of calibration corrections made to Advanced Very High Resolution Radiometer (AVHRR) observations and to Advanced Microwave Sounding Unit (AMSU) data. The use of a network of surface- based GPS receivers to determine atmospheric integrated precipitable water vapor (IPW) accurately and precisely with 30-min temporal resolution now provides an effective and rapid means of validating satellite moisture retrievals. The method has been used successfully to validate observations from the Atmospheric Infrared Sounder (AIRS) and sounders on NOAA’s Geosynchronous Operational Environmental Satellites (GOES). Although the method does not provide a vertical profile of moisture, it is shown to provide an effective scaling constraint for satellite and radiosonde intercomparisons.