Brightness temperatures (Microwave Imager FCDR)

FCDR MWI ED4 example Source: CM SAF

The CM SAF FCDR of Microwave Imager radiances comprises homogenized and inter-calibrated brightness temperatures (BTRs) from the SMMR, SSM/I and SSMIS radiometers. It covers the time period from October 1978 to December 2022 including all available data from the SMMR radiometer aboard Nimbus–7, the SSM/I radiometers aboard F08, F10, F11, F13, F14, and F15 and the SSMIS radiometers aboard F16, F17, and F18. The homogenization and inter-calibration procedures ensure the long-term stability of the FCDR for climate related applications. All available raw data records have been reprocessed to a common standard, starting with the calibration of the raw Earth counts. The data processing accounts for several known issues with the instruments and corrects calibration anomalies due to along-scan inhomogeneity, moonlight intrusions, sunlight intrusions, and emissive reflector. Corrections for SMMR are limited because the SMMR raw data records were not available. Furthermore, the inter-calibration model incorporates a scene-dependent inter-satellite bias correction and a non-linearity correction to the instrument calibration. The data files contain all available original sensor data (SMMR: Pathfinder Level 1b) and metadata to provide a completely traceable climate data record. Inter-calibration and Earth incidence angle normalization offsets are available as additional layers within the data files in order to keep this information transparent to the users. The data record is complemented with radiometer sensitivities, quality flags, surface types, and Earth incidence angles. Further details on the products in general, on retrieval details and physical basis as well as on quality can be found in the Product User Manual (PUM), the Algorithm Theoretical Basis Documents (ATBD), and the Validation Reports (ValRep).
The product can be ordered via the Web User Interface.

CM SAF also provides coefficients for intercalibrating observations by microwave imager instruments TMI, AMSR-E and GMI to this FCDR (Technical Report-Microwave Imager Inter-calibration).

Reference:

• Poli, P., C. Peubey, K. Fennig, M. Schröder, R. Roebeling, A. Geer: Pre-assimilation feedback on a Fundamental Climate Data Record of brightness temperatures from Special Sensor Microwave Imagers: A step towards MIPs4Obs? ERA report series, No. 19, August 2015.
• Fennig, K., M. Schröder, A. Andersson, R. Hollmann: A Fundamental Climate Data Record of SMMR, SSM/I, and SSMIS brightness temperatures. Earth Syst. Sci. Data, 12, 647–681, https://doi.org/10.5194/essd-12-647-2020, 2020.

HK / Aug2024