NOAA Climate Data Record (CDR) of SSM/I and SSMIS Microwave Brightness Temperatures, RSS Version 7

This Version 7 NOAA Fundamental Climate Data Record (CDR) from Remote Sensing Systems (RSS) contains brightness temperatures that have been inter-calibrated and homogenized over the observation time period. The temperature data are from the Special Sensor Microwave Imager (SSM/I) and Special Sensor Microwave Imager Sounder (SSMIS) series of passive microwave radiometers carried onboard the Defense Meteorological Satellite Program (DMSP) satellites. These satellite sensors measure the natural microwave emission coming from the Earth’s surface in the spectral band from 19 to 85 GHz. This dataset encompasses data from a total of seven satellites including the SSM/I sensors on board DMSP satellites F08, F10, F11, F13, F14, and F15 as well as the SSMIS sensors on board DMSP satellite F17. The data record covers the time period from July 1987 through the present with a one month latency. The spatial and temporal resolutions of the CDR files correspond to the original resolution of the source SSMI(S) observations. There are roughly 15 orbits per day with a swath width of approximately 1400 km resulting in nearly global daily coverage. The spatial resolution of the data is a function of the sensor/channel and varies from approximately 50 km for the lowest frequency channels to approximately 15km for the high-frequency channels. The output parameters include the observed brightness temperatures for each of the seven SSM/I channels and 24 SSMIS channels at the original sensor channel resolution along with latitude and longitude information, time, quality flags, and view angle information. The file format is netCDF-4 with added metadata that follow the Climate and Forecast (CF) Conventions and Attribute Convention for Dataset Discovery (ACDD). There are three major changes in the Version 7 processing: (1) the water vapor continuum absorption model was re-derived, (2) the clear-sky bias in cloud water was removed and the data format for cloud water was changed, and (3) the beamfilling correction in the rain algorithm was modified. Relative to Version 6, Version 7 has: (1) increased vapor values in the range of 50-60 mm by 1%, (2) increased vapor values above 60 mm by 2-3%, (3) cloud data changed to the range of cloud water values: -0.05 to 2.45 mm (cloud data format has changed), and (4) increased the global mean rain rates by about 16% (mostly due to changes in the extratropical values).