Quality control of a fundamental climate data record from geostationary observations: calibration, navigation and radiometric quality

Satellite Fundamental climate data records (FCDR) are long-term raw satellite observations (i.e., radiances) whose calibration, navigation and radiometric errors are well-characterized and documented. The National Climatic Data Center (NCDC) is striving to produce an FCDR from the International Satellite Cloud Climatology Project (ISCCP) B1 data. The B1 data consists of geostationary full-disk observations every 3 hours beginning in 1983 (through the present) from most of the world's meteorological geostationary satellites (e.g., Europe's Meteosat, Japan's GMS and the U.S. GOES series). Primarily, the visible and infrared channels are available for the entire dataset, however more channels are present where available (i.e., the water vapor channel on Meteosat and all channels from GOES-8 and beyond). The first step of salvaging information from the B1 data was recently completed: documenting the format and navigation of the entire record. In fact, the 23 years of data are currently available in a unified format with navigation algorithms documented. Since the data is more accessible, the quality of the calibration, navigation and noise can now be documented. The navigation quality is assessed in comparing infrared observations with those from AVHRR. Calibration is evaluated with intercomparisons of B1 data with both HIRS and AVHRR. Long-term noise characteristics are determined using a time-series of statistical parameters sensitive to noise (e.g., observations of space). The results of these comparisons help to further characterize the ISCCP B1 data set and prepare it for use in retrieving geophysical climate data records.