Precipitation decrease in the western Arctic, with special emphasis on Barrow and Barter Island, Alaska

Abstract

Over the Arctic during the last few decades a decrease in annual precipitation and snow depths have been observed; this decrease is especially pronounced during the winter months. This decrease was not only found over northern Alaska but also over the high latitude Canadian stations and Russian drift stations. Further, satellite monitoring of North America snow cover has revealed a significant decreasing trend in mid-spring cover since 1972. The temperature increased during the last few decades in the Arctic, hence the simplest explanation—normally increased temperature leads to high precipitation—is not valid. A causal explanation for these trends had been related to the shift of the Aleutian low and Arctic high. This study, with special emphasis on the surface observation data from Barrow and Barter Island, indicates: (i) not only the frequency, but the mean intensity of precipitation has decreased; (ii) the amount of total cloud cover, and in particular, low cloudiness, has decreased with time; (iii) sea-level pressure did not show any significant trends. Variability in atmospheric pressure, however, decreased with time, suggesting that either the intensity and:or frequency of cyclones has decreased; (iv) a shift in seasonal resultant winds at Barrow has been observed.