Detection of pan-Arctic terrestrial snowmelt from QuikSCAT, 2000-2005. Remote Sensing of Environment

Time series of enhanced resolution QuikSCAT scatterometer data were used to detect terrestrial snowmelt onset in the pan-Arctic during the 2000 – 2005 period. Based on the decrease/increase of backscatter upon the appearance/disappearance of liquid water in snow, multiple melt events were identified by a threshold method. Melt events with the longest melt duration or the largest intensity were defined as the primary melt events. There is a good correspondence between the estimated melt onset and air temperature and snow depth observations from WMO weather stations. Maps of the dates of snowmelt onset and the anomalies were produced for each year. The timing of snowmelt onset directly affects the surface energy and water balances, with important implications for the regional to global weather forecasts, carbon source-sink dynamics, and global change assessment and monitoring