Atmospheric temperature climate data records from satellite microwave sounders

Abstract

This chapter reviews the simultaneous nadir overpass (SNO) method to remove time-varying inter-satellite biases at the swath level for developing a well-inter-calibrated Level-1c radiance fundamental climate data record (FCDR) from the microwave sounding unit (MSU) and advanced MSU observations onboard historical NOAA polar-orbiting satellite series. The SNO method has effectively minimized scene temperature-dependent radiance biases and solar heating-related instrument temperature variability in the radiances, resulting in global mean inter-satellite biases of only 0.05-0.1 K. Twenty years of the SNO-calibrated Level-1c radiances had been assimilated into the NCEP Climate Forecast System Reanalysis (CFSR) and NASA Modern Era Retrospective analysis for Research and Applications (MERRA) reanalysis, yielding much consistent bias correction patterns across different satellites compared to those using prelaunch-calibrated radiances. The SNO-calibrated radiances were further used to generate the NOAA Center for Satellite Applications and Research (STAR) version of deep-layer atmospheric temperature climate data record. The chapter reviews various residual bias correction algorithms for developing the STAR layer temperature time series, including antenna pattern correction, limb adjustment, diurnal drift correction, geo-location-dependent bias removal, and channel frequency difference between MSU and AMSU. With these adjustments, well-merged atmospheric temperature time series were generated for climate change monitoring and research.