Climatology of extreme downslope windstorms in the Russian Arctic

Abstract

This paper presents the climatology of downslope windstorms in the Russian Arctic – bora on Novaya Zemlya, windstorms on Spitsbergen, in Tiksi and Pevek, bora on Wrangel Island – in connection with the large-scale circulation. Statistical analysis of wind speed and air temperature during windstorms, the frequency of the phenomenon, as well as analysis of trends in frequency and intensity of downslope windstorms in the late 20th and early 21st centuries were carried out. Similarity of the large-scale background (incoming) flow is evident for all regions; the most frequent features of the incoming flow are elevated inversion and low-tropospheric jet stream. The observed transformation of the incoming flow from weak to strong windstorm along with the relatively weak linear correlation between downslope wind speed and upwind-side flow characteristics suggest that there are nonlinear connections between windstorms and the incoming flow. We found significant negative trends in Wrangel Island bora frequency and intensity, connected largely with the Arctic circulation variability and associated sea-ice loss. A negative trend in intensity of windstorms was also found in Tiksi and Pevek, associated more with midlatitudes circulation patterns.