The Permafrost CCI project is establishing Earth Observation (EO) based products for the permafrost Essential Climate Variable (ECV) spanning the last two decades. Since ground temperature and thaw depth cannot be directly observed from space-borne sensors, a variety of satellite and reanalysis data are combined in a ground thermal model. The algorithm uses remotely sensed data sets of Land Surface Temperature (MODIS LST/ ESA LST CCI) and landcover (ESA LandcoverCCI) to drive the transient permafrost model CryoGrid 2, which yields thaw depth and ground temperature at various depths, while ground temperature forms the basis for permafrost fraction.

Input data: MODIS Land surface temperature is used as the main input for the L4 production for 2003-2018 data. Sensors of auxiliary data are listed in the meta data.
Downscaled and bias corrected ERA reanalyses data based on statistics of the overlap period between ERA reanalysis and MODIS LST are used for data before 2003. Sensors of auxiliary data are listed in the meta data.