Linking drought indices in the Atlantic sector of the High Arctic (Svalbard) to atmospheric circulation

Abstract

Based on the long-term climatological data from Ny Alesund, Svalbard Airport – Longyearbyen and Hornsund Polish Polar Station, we undertook an analysis of drought indices on West Spitsbergen Island, Svalbard for the period 1979–2019. The features and causes of spatio-temporal variability of atmospheric drought on Svalbard were identified, as expressed by the Standardised Precipitation Evapotranspiration Index (SPEI). It was possible to indicate several-years long periods with the SPEI indicating a domination of drought or wet conditions. Long-term variability of annual and half-year (May-October) values of SPEI showed a prevalence of droughts in the 80-ties and in the first decade of the 21st century while wet seasons were frequent in the 90-ties and in the second decade of the 21st century. Seasonal SPEIs were characteristic of great inter-annual variability. In MAM and JJA droughts were more frequent after 2000; in the same period in SON and DJF, the frequency of wet seasons increased. The most remarkable changes in the scale of the entire research period were estimated for autumn where negative values of SPEI occur more often in the first part of the period and positive values dominate in the last 20 years. The long-term course of the variables in subsequent seasons between 1979–2019 indicates strong relationships between the SPEI drought index and anomalies of precipitable water and somewhat weaker relationships with anomalies of sea level pressure.