Pre-assimilation feedback on a Fundamental Climate Data Record of brightness temperatures from Special Sensor Microwave Imagers: A step towards MIPs4Obs?

Title
Pre-assimilation feedback on a Fundamental Climate Data Record of brightness temperatures from Special Sensor Microwave Imagers: A step towards MIPs4Obs?
Report
Date Published
08/2015
Series/Collection
ERA Report Series
Document Number
19
Author
P. Poli
C. Peubey
K. Fennig
M. Schroeder
R. Roebelling
Alan Geer
Event Series/Collection
ERA Report
Abstract The Fundamental Climate Data Record (FCDR) generated by the Climate Monitoring Satellite Application Facility (CM SAF) of EUMETSAT from brightness temperatures collected by the series of Special Sensor Microwave Imager (SSM/I) instruments is considered for use in the upcoming ERA5 global reanalysis. This report presents a first account of the information gained from the reanalysis user side, albeit before assimilation, using clear-sky radiative transfer computations from existing reanalyses ERA-Interim and ERA-20C. The FCDR patches gaps in the SSM/I record at ECMWF and adds 13 satellite-years. A methodology to compare data records confirms the introduction of time offsets in the FCDR, consistently with leap seconds. The FCDR features a time consistency that is superior to the original record, thanks to the intercalibration. The ERA-20C reanalysis reproduces better than ERA-Interim the inter-annual variability of the FCDR, but misses on the intra-monthly variability. The comparison process generates a data record augmented by pre-assimilation feedback. This followed approach of augmenting an observational dataset with model-equivalents could in fact be generalized, and adopted to project not only reanalysis output but also climate model output into observational data space. This would complement the Obs4MIPs initiative. Where Obs4MIPs is from the onset designed to bring observations to the modelers, in the space and shape they are used to, MIPs4Obs would bring the model outputs to the community of observers, retaining the granularity of the original observation records.
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