NOAA Climate Data Record (CDR) of AVHRR Polar Pathfinder Extended (APP-X) Cryosphere, Version 2

NOAA Climate Data Record (CDR) of the eXtended AVHRR Polar Pathfinder (APP-X) cryosphere contains 19 geophysical variables over the Arctic and Antarctic for the period 1982 - present. All of them have undergone various degrees of validation, though not all are considered CDR quality. The variables are (those considered by the developers to be CDR-quality are identified with an asterisk): Surface temperature, all-sky, snow, ice, and land* Surface albedo, all-sky* Sea ice thickness* Surface type Cloud mask* Cloud particle thermodynamic phase Cloud optical depth Cloud particle effective radius Cloud temperature Cloud pressure Cloud type Downwelling shortwave radiation at the surface* Downwelling longwave radiation at the surface* Upwelling shortwave radiation at the surface* Upwelling longwave radiation at the surface* Upwelling shortwave radiation at the TOA* Upwelling longwave radiation at the TOA* Shortwave cloud radiative forcing at the surface Longwave cloud radiative forcing at the surface APP-x data products are mapped to a 25 km EASE grid at two local solar times: 04:00 and 14:00 for the Arctic, and 02:00 and 14:00 for the Antarctica. Using local solar time rather than standard UTC times provides better information on diurnal differences at all locations. The latest update to version 2 includes folding in the APP FCDR updates (updated calibration coefficients for AVHRR GAC visible channels) along with improved algorithms for the land mask, cloud mask, and ice thickness.