The spring snowmelt phenology in Alaska from 2001–2019

The Normalized Difference Snow Index (NDSI) of the MODIS Terra Snow Cover Daily L3 Global 500m Grid data (MOD10A1.v006) is used to derive the start of snowmelt (SOM) and the end of snowmelt (EOM) in spring. The data coverage includes Alaska and part of Canada Yukon from 55°N to 72°N for the years between 2001 and 2019. The MOD10A1 is resampled to 1-km resolution with nearest-neighbor interpolation. The algorithm takes 8-day maximum value composite NDSI data, performs data stacking, smoothing, and then calculates the SOM and EOM metrics.