The Extended AVHRR Polar Pathfinder (APP-x) Product

Version 6.0

Data Details FTP Site Validation Info Problems
This data set consists of AVHRR retrievals of surface, Top Of the Atmosphere (TOA), cloud, and sea ice properties as well as radiative fluxes for the period 1982 - 2011 over the Arctic and Antarctic at a 25 km resolution. The images times are 1400 and 0400 (Arctic) or 0200 (Antarctic) local solar times. Resulsts are calculated on a twice-daily basis, but only monthly mean images and area-averaged values are currently online.

The standard AVHRR Polar Pathfinder (APP) product includes gridded radiances, viewing and illumination geometry, clear sky surface temperature and albedo, and three cloud masks at a 5 km resolution. We have extended the standard APP product to include all-sky surface temperature, all-sky surface albedo, cloud information  (amount, type, particle phase, effective radius, optical depth, temperature and pressure), sea ice properties, and radiative fluxes as well as cloud radiative effect ("forcing"). We refer to this dataset as APP-x.

The retrieval algorithms of the Cloud and Surface Parameter Retrieval ( CASPR) system were applied. The following parameters are available:
 
Surface and Clouds: Radiation:Cryosphere
  • Surface temperature, clear or all-sky
  • Broadband albedo, clear or all-sky
  • Cloud particle effective radius
  • Cloud optical depth
  • Cloud particle phase
  • Surface type mask
  • Cloud top temperature
  • Cloud top pressure
  • Cloud mask
  • Cloud type
  • Precipitable water
  • Sunglint mask
  • Downwelling shortwave flux at the surface
  • Downwelling longwave flux at the surface
  • Upwelling shortwave flux at the surface
  • Upwelling longwave flux at the surface
  • Downwelling shortwave flux at the top of the atmosphere
  • Upwelling shortwave flux at the top of the atmosphere
  • Upwelling longwave flux at the top of the atmosphere
  • Shortwave cloud forcing at the surface
  • Longwave cloud forcing at the surface
  • Ice identification
  • Ice concentration
  • Ice thickness
  • Ice age
  • More to develop

The area of coverage for the Arctic and Antarctic are shown in the figures below.

Here are a few examples of the data set: