Variability of observed temperature-derived climate indices in the Arctic

Arctic temperature is analyzed in view of its extremes based on climate indices derived from daily mean, maximum, and minimum temperature. This analysis is done for the pan Arctic domain and region-specific for the eastern and western Russian Arctic. The variability of temperature-related indices over the last four decades is presented, in which the spatial distribution and regional differences as well as its temporal trends are discussed. The analysis is based on ERA40 data and station data in the Russian Arctic. Station-based results for 1958–2008 show a significant decrease of frost days (− 0.8 days/decade) over the eastern Russian Arctic in spring. The trends in warm (cold) spell days are not statistically significant; except in western Russian Arctic in summer for cold spell days (− 2 days/decade). The inter-annual variability of the indices is large and shows pronounced decadal variations. ERA40 data generally reproduce well the inter-annual variability in the climate indices as seen in observations, but they show some deficiencies in the magnitudes and trends of the indices.