Highly Consistent Brightness Temperature Fundamental Climate Data Record From SSM/I and SSMIS

A continuous and consistent fundamental climate data record (FCDR) from satellite observations is an essential source for climate research. In this study, a highly consistent multichannel brightness temperature (TB) FCDR during 1991–present has been developed using measurements from two Special Sensor Microwave Imagers (SSM/I) onboard F11 and F13 satellites and one Special Sensor Microwave Imager/Sounder (SSMIS) onboard F17 satellite from the U.S. Defense Meteorological Satellite Program (DMSP). The hardware differences between these instruments were corrected by a combination of several technologies including the principal component analysis (PCA), use of the third instrument as an intermediate, and the weighted average approach which takes into account interchannel covariability and observation matchup issues. After intercalibration, all imagers were homogenized with SSMIS, which was used as an observation reference. The mean biases of the recalibrated TBs for almost all channels between any two instruments are less than 0.2 K globally with the standard deviations (STDs) less than 1.2 K. This resulted in a 30-year long continuous and stable FCDR. Based on this FCDR, a long time series of column water vapor (CWV) over the global oceans was retrieved. Validation of this retrieved moisture product against reanalysis data and site measurements from radiosonde and Global Navigation Satellite System (GNSS) resulted in reasonably good accuracy, suggesting that the presented FCDR has high application potential for climate research.