Spatio-temporal variability of snowmelt across Svalbard during the period 2000-08 derived from QuikSCAT/SeaWinds scatterometry

摘要

Significant changes in Arctic systems are underway, which are attributed to global warming. An important example is reduction in snow and ice coverage due to intensified melting in many regions. Active microwave instruments are used to detect surface melt and freeze-up based on the high sensitivity of radar backscatter to liquid water in the snow. We monitor two snowmelt parameters, the annual total of melt days and the date of summer melt onset across the archipelago of Svalbard using microwave backscatter measurements from the Ku-band scatterometer SeaWinds onboard the QuikSCAT satellite. Our analysis covers a nine-year time span from 2000 to 2008. Meteorological data from synoptic and automatic weather stations at several locations in Svalbard are used to investigate climatologic controls on pattern and timing of snowmelt. Svalbard temperature and precipitation regimes are highly variable throughout the year due to the location of the archipelago within a zone that is characterized by the convergence of atmospheric fronts from the Arctic Ocean, Nordic seas and the Barents Sea. Accordingly, our results show pronounced regional and interannual variability in snowmelt dynamics. However, we do find a trend towards earlier summer melt onset and an increasing number of melt days per year over the nine-year period of study. Our findings agree with climate-model predictions that project increasingly warmer and wetter conditions in the Arctic.