Inter- and intra-annual changes in air temperature and precipitation in western Spitsbergen

Natural systems are characterized by seasonal and inter-annual variability. In the Arctic, changes in annual runs of air temperature and precipitation play crucial roles and have implications for the abiotic and biotic environment. In our study, we investigate seasonality and inter-annual variability of air temperature and precipitation at three stations with the longest diurnal instrumental records in Spitsbergen: the Polish Polar Station Hornsund, Longyearbyen Airport and Ny-Alesund. For that purpose, we used the novel method of analysis Moving Average over Shifting Horizon (MASH), combined with trend estimation. The application of MASH helps detecting changes of seasonality in the data by filtering out the effects of periodicity of the variables. The results show that the tendencies of changes are not evenly distributed throughout the year. In the case of air temperature, upward trends were detected, with the most pronounced changes in the freezing season and slight changes during summer. The shape of the annual run has also changed, with a shift of the coldest months from December and January to March and April. In terms of precipitation, the highest increases were obtained for the late melting season, autumn and early winter, especially pronounced in Hornsund and Ny-Alesund. Changes in daily air temperature and precipitation totals were strongly linked to sea ice conditions. An influence of other climatic indices was also statistically significant, but varied depending on the month.