Inter-calibrating, Multi-instrument Microwave Ocean Data Records over Three Decades

Abstract:

Satellite microwave radiometers have been in continuous operation since 1987. When inter-calibrated and consistently processed, the data from a series of DMSP SSM/I and SSMIS sensors, TRMM TMI, Coriolis WindSat, Aqua AMSR-E, GCOM-W1 AMSR2, and GPM GMI collectively result in a long-term high-quality ocean data set of surface winds, atmospheric water vapor, cloud liquid water content, rain rate, and for some instruments, sea surface temperature and wind direction. Slight variations in frequencies, design and satellite orbits stress the need for carefully implementing an inter-calibration method, so as not to introduce trends or jumps when new instruments begin or when old instruments drift and/or die. The authors have developed a robust inter-calibration method using a published, well-developed and validated radiative transfer model (RTM) as the calibration standard. Most of the sensor data for this nearly 30-year period are available as the Version-7 RTM standard. The GMI sensor, recently launched in 2014, has strict calibration accuracy requirements and was built to have greater precision than any previous microwave sensor. We have utilized the dual calibration and non-linearity-measurement systems built into GMI to improve the RTM, which is now Version-8. In this talk we will present an overview of our calibration procedures and outline the steps required to produce climate quality earth data records. We also intend to present the latest validation results and provide information on recent changes in distribution, format, and availability for these already-popular data products.