Fundamental Climate Data Record of Microwave Imager Radiances, Edition 4

The CM SAF FCDR of Microwave Imager Radiances comprises inter-calibrated brightness
temperatures (BTRs) from the SMMR, SSM/I and SSMIS radiometers. This 4th edition covers the time period
from October 1978 to December 2020 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. This data record has been extended by two more years of SSMIS data
in December 2023. This prolongs the end of the covered time period to December 2022.
The FCDR provides homogenised and inter-calibrated BTRs in a
user-friendly data format. SMMR, SSM/I and SSMIS data are used for a variety of applications,
such as analyses of the hydrological cycle and remote sensing of sea ice. The improved
homogenization and inter-calibration procedure 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, to ensure a completely
homogenized data record. 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. Also, an adjustment to the SSMIS
geolocation has been implemented in order to improve the consistency. 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.