Pan arctic terrestrial snowmelt trends (1979–2008) from spaceborne passive microwave data and correlation with the Arctic Oscillation

We report pan-arctic terrestrial snowmelt trends for the period 1979 – 2008 derived from spaceborne microwave brightness temperature (Tb) and study the correlation between these trends and the Arctic Oscillation (AO). Melting is detected using a spatially and temporally dynamic algorithm using the difference between daytime and nighttime Tb values (Diurnal Amplitude Variations, DAV). Results indicate statistically significant negative trends for melt onset and end dates as well as for the length of the melt season. On the average, over the past 30 years melt has been starting (finishing) ∼0.5 days/year (∼1 days/year) earlier and the length of the melting season is shortening by ∼0.6 days/year. Results indicate that the AO index variability can explain up to 50% of the melt onset variability over Eurasia and only 10% of that over North America, consistent with spatial patterns of surface temperature changes related to the AO