Changes in snow cover over Northern Eurasia in the last few decades

Abstract

Daily snow depth (SD) and snow cover extent around 820 stations are used to analyse variations in snow cover characteristics in Northern Eurasia, a region that encompasses the Russian Federation. These analyses employ nearly five times more stations than in the previous studies and temporally span forty years. A representative judgement on the changes of snow depth over most of Russia is presented here for the first time. The number of days with greater than 50% of the near-station territory covered with snow, and the number of days with the snow depth greater than 1.0 cm, are used to characterize the duration of snow cover (SCD) season. Linear trends of the number of days and snow depth are calculated for each station from 1966 to 2007. This investigation reveals regional features in the change of snow cover characteristics. A decrease in the duration of snow cover is demonstrated in the northern regions of European Russia and in the mountainous regions of southern Siberia. An increase in SCD is found in Yakutia and in the Far East. In the western half of the Russian Federation, the winter-averaged SD is shown to increase, with the maximum trends being observed in Northern West Siberia. In contrast, in the mountainous regions of southern Siberia, the maximum SD decreases as the SCD decreases. While both snow cover characteristics (SCD and SD) play an important role in the hydrological cycle, ecosystems dynamics and societal wellbeing are quite different roles and the differences in their systematic changes (up to differences in the signs of changes) deserve further attention.

Attribution of spring snow water equivalent (SWE) changes over the northern hemisphere to anthropogenic effects

“…However, remarkable increasing trends were observed for the southern part of east Eurasia, mainly due to significant increases in accumulated precipitation from the previous winter to spring period. The increases in spring SWE for east Eurasia for the last few decades are consistent with the findings by Bulygina et al (2009Bulygina et al ( , 2011 and Wu et al (2014), based on spring SCE and/or SWE.…”

Relevance of Hydro-Climatic Change Projection and Monitoring for Assessment of Water Cycle Changes in the Arctic

“…However, contradictory trends in discharge and precipitation have also been reported (Berezovskaya et al 2004;Milliman et al 2008). For some of the basins in our study, gauge undercatch in combination with recently reported increases in snowfall over Siberia (Bulygina et al 2009, Rawlins et al 2009b can to some degree explain the greater increases in observed runoff than in observed precipitation.…”

“…Most basins exhibit excess runoff relative to the observed precipitation changes, with in some cases extreme discrepancies. Snowfall observation bias, which implies that increases in snowfall are not fully accounted for in precipitation measurements, may explain the apparent excess water for some basins (Bulygina et al 2009;Rawlins et al 2009b). Reduced evaporation due to earlier snowmelt and earlier associated runoff (Milliman et al 2008) is another possible contributing factor.…”

Variability in snow cover phenology in China from 1952 to 2010

“…In North America, snow depth in central Canada showed the greatest decrease (Dyer and Mote, 2006), and snowpack in the Rocky Mountains in the United States declined (Pederson et al, 2013). However, in situ data showed a significant increase in snow accumulation in winter but a shorter snowmelt season over Eurasia (Bulygina et al, 2009). Decrease in snowpack has also been found in the European Alps in the last 20 years of the twentieth century (Scherrer et al, 2004), but a very long time series of snowpack suggests large decadal variability and overall weak long-term trends only (Scherrer et al, 2013).…”

“…The SCDs vary in space and time and contribute to climate change over short timescales (Zhang, 2005), especially in the Northern Hemisphere. Bulygina et al (2009) investigated the linear trends of SCDs observed at 820 stations from 1966 to 2007, and indicated that the duration of snow cover decreased in the northern regions of European Russia and in the mountainous regions of southern Siberia, while it increased in Yakutia and the Far East. Peng et al (2013) analysed trends in the snow cover onset date (SCOD) and snow cover end date (SCED) in relation to temperature over the past 27 years from over 636 meteorological stations in the Northern Hemisphere.…”