Satellite microwave assessment of Northern Hemisphere lake ice phenology from 2002 to 2015
Abstract. A new automated method enabling consistent satellite assessment of seasonal lake ice phenology at 5 km resolution was developed for all lake pixels (water coverage 90 in the Northern Hemisphere using 36.5 GHz H polarized brightness temperature (Tb) observations from the Advanced Microwave Scanning Radiometer for EOS and Advanced Microwave Scanning Radiometer 2 (AMSR E/2) sensors. The lake phenology metrics include seasonal timing and duration of annual ice cover. A moving t test (MTT) algorithm allows for automated lake ice retrievals with daily temporal fidelity and 5 km resolution gridding. The resulting ice phenology record shows strong agreement with available ground based observations from the Global Lake and River Ice Phenology Database (95.4 temporal agreement) and favorable correlations (R) with alternative ice phenology records from the Interactive Multisensor Snow and Ice Mapping System (R 0.84 for water clear of ice (WCI) dates; R 0.41 for complete freeze over (CFO) dates) and Canadian Ice Service (R 0.86 for WCI dates; R 0.69 for CFO dates) Analysis of the resulting 12 year (2002 2015) AMSR E/2 ice record indicates increasingly shorter ice cover duration for 43 out of 71 (60.6 Northern Hemisphere lakes examined, with significant (p