Construction of consistent temperature records in the lower stratosphere using global positioning system radio occultation data and microwave sounding measurements

In this study, we use FORMOSAT-3/Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Global Positioning System (GPS) radio occultation (RO) data to simulate Advanced Microwave Sounding Unit (AMSU) brightness temperatures (Tbs) for the lower stratosphere and compare them to AMSU Tbs from different National Oceanic and Atmospheric Administration (NOAA) missions in July 2007. Our analysis shows that because COSMIC data do not contain orbit drift errors and are not affected by on-orbit heating and cooling of the satellite component, they are very useful to identify the AMSU time/location-dependent biases for different NOAA missions. We also examine the consistency of the calibration coefficients among collocated NOAA AMSU Tb pairs (e.g., NOAA15-NOAA16, NOAA16-NOAA18, and NOAA15-NOAA18) and COSMIC-NOAA pairs. The usefulness of the COSMIC-calibrated AMSU Tbs for calibrating other overlapping AMSU Tbs from different platforms is also examined. These results demonstrate the potential to use both GPS RO and microwave sounding data to construct consistent climate temperature records.