A 41-year (1979–2019) passive-microwave-derived lake ice phenology data record of the Northern Hemisphere

Abstract. Seasonal ice cover is one of the important attributes lakes in middle- and high-latitude regions. The annual freeze-up breakup dates as well duration (i.e., lake phenology) are sensitive to weather climate; hence, they can be used an indicator climate variability change. In addition optical, active microwave, raw passive microwave data that provide daily observations, Calibrated Enhanced-Resolution Brightness Temperature (CETB) dataset available from National Snow Ice Data Center (NSIDC) provides alternate source brightness temperature (TB) measurements for determination phenology on a 3.125 km grid. This study Scanning Multichannel Microwave Radiometer (SMMR), Special Sensor Microwave/Imager (SSM/I), Imager/Sounder (SSMIS) CETB extract 56 across Northern Hemisphere 1979 2019. According differences TB between open water, threshold algorithm based moving t test method was applied determine status grids located at least 6.25 away shore, each were then extracted. When could extracted more than satellite over overlapping periods, results offering largest number observations prioritized. showed strong agreement with existing product derived Advanced Earth Observing System (AMSR-E) 2 (AMSR2) (2002 2015), mean absolute errors ranging 4 d. Compared near-shore situ results, while different terms spatial coverage, still overall consistency. produced record also displayed significant consistency when compared historical maximum Laurentian Great Lakes North America. From 2019, average complete freezing forming basis 153 161 d, respectively. – new (CDR) will valuable information user community about changing last decades. https://doi.org/10.1594/PANGAEA.937904 (Cai et al., 2021).