These files provide daily under-ice estimates of Photosynthetically Active Radiation (PAR) since the launch of CryoSat-2. Estimates are provided based on daily interpolation of (1) CryoSat-2 and (2) blended CryoSat-2 and Sentinel 3A/B freeboards derived using the Lognormal Altimeter Retracker Model (LARM) [Landy et al. 2020] together with snow depths and snow densities from SnowModel-LG [Liston et al., 2020].
The other estimate is based on daily interpolation of ICESat-2 snow freeboard heights [ATL10] and converted to ice thickness using SnowModel-LG snow depth and density. Together with information on snow depth from SnowModel-LG, surface albedo, skin temperature and incoming solar radiation from the AVHRR Polar Pathfinder APP-X product [Key et al. 2019] and sea ice concentrations from the NASA Team algorithm, daily under-ice light estimates are provided for sea ice areas only.