Regional characteristics of Arctic temperature variability: comparison of observations with regional climate simulations

Regional-scale interannual variability of the seasonal air temperature and the intra-seasonal extreme temperature range and their seasonality were investigated for the pan-Arctic and also (in more detail) for Russian Arctic land. Daily mean, minimum, and maximum temperatures were obtained from the 'Global Summary of Day' station data set for the period 1958 to 2008 (51 yr) and from the gridded data of the ERA40 reanalysis and regional climate model HIRHAM simulations for the period 1958 to 2001 (44 yr). Because of a high degree of variability in both temperatures and temperature extremes in the analysis period, it was difficult to identify significant trends. The trends in seasonal temperatures were positive overall, but not significant for the western Russian Arctic. A significant warming in the seasonal temperature was confirmed for the eastern Russian Arctic (0.4 to 0.9 degrees C decade(-1), depending on the season, in the 51 yr station record). Generally, the trends in the seasonal extreme temperature range were of mixed sign and were not statistically significant for the longer record, 'except for the negative trend of -0.3 degrees C decade(-1) for the eastern Russian Arctic in summer. The interannual variability of both temperature measures in turn showed a pronounced decadal variability and considerable regional and seasonal characteristics. The HIRHAM model reproduced the observed temporal evolution and magnitude of the observed temperature variability reasonably well.