This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, consists of two global records of the daily freeze/thaw (F/T) status of the landscape. The primary record is derived from radiometric brightness temperatures acquired between 1979 and 2017 by three satellite-based passive microwave sensors: the Scanning Multichannel Microwave Radiometer (SMMR), the Special Sensor Microwave/Imager (SSM/I), and the Special Sensor Microwave Imager/Sounder (SSMIS).
A second, synergistic record is available for the years 2002 to 2017, derived from observations acquired by the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) and the Advanced Microwave Scanning Radiometer 2 (AMSR2).