Variability and Changes of the Growing Season Length and Frost Days Number in Russian sub-Arctic

Abstract

Observational data from the Russian sub-Arctic stations are used to investigate long-term variability of the growing season length (GSL) and the number of frost days (FD) in 1949-2013. Consistent with the global warming pattern we find a trend-like increase (decrease) of GSL (FD) which is evident since early 1970 th of the last century. These trendlike changes are best pronounced at Western stations (i.e. in European Russia and western Siberia) and they are essentially smaller to the East. Although we find some significant links to regional teleconnections (such as Scandinavian, East Atlantic and West Pacific teleconnections), in general our results imply rather weak impact of large scale atmospheric dynamics on interannual variability of GSL and FD. Further analysis of correlations between GSL and FD on the one side and snow cover on the other side revealed generally stronger links to snow cover compared to teleconnections. However, revealed links to regional atmospheric teleconnections and snow cover are significantly impacted by the linear trends. In general, our results imply that compared to large scale atmospheric dynamics impacting interannual variability, snow cover (being a result of wintertime synoptic activity) plays a more important role in decadal-interdecadal variations of GSL and FD in Russian sub-Arctic, which may have some value regarding predictability of the summer climate in the region.