International Satellite Cloud Climatology Project (ISCCP), Raw Radiance Data (B1)

In 1983, the International Satellite Cloud Climatology Project (ISCCP) began collecting satellite data from the international geostationary meteorological satellites as well as NOAA POES satellites around the world in an effort to characterize global cloudiness. Due to computing limitations at the time, data were subsampled to ~10 km were archived for future processing. This subsampled data is called B1 data. ISCCP B1 data are a collection of measurements from imagers on international geostationaru satellites which are sub-sampled to approximately 10 km and 3 hourly. The ISCCP B1 data are primarily composed of visible (VIS), infrared water vapor (IRWVP) and infrared window (IRWIN) channels (roughly 0.6um, 6.7um and 11um, respectively). The visible and infrared channels are window channels that are more sensitive to the surface than the atmosphere which helps discriminate clouds from clear sky [2]. Conversely, the water vapor channel is mostly opaque and as such, is not used in the ISCCP cloud mask algorithm.