Observational Study on Sublimation from the Snow Surface in Northern Eurasia

In northern Eurasia region, both of snow-cover water equivalence and winter precipitation has been demonstrated to be range of 50 to 150 mm. Sublimation from snow surfaces has been identified as an important hydrological process at high altitudes and in high latitude regions, involving complex mass and energy exchanges. Since 2002, intensive observations, to dressing winter hydrological land processes, have been conducted in Mogot experimental watershed, which is locating in the southern mountain taiga region of eastern Siberia of Russia (55.5_E#8249;N, 124.7_E#8249;E), and also on snow-tussock grassland in Nalaikh of Mongolia (47o45'N, 107o20'E), which locating in southern periphery region of Eurasia cryosphere. Snow sublimation has been quantitatively dressed by aero-dynamics or Lysimeter method. Effects of topography and vegetation cover to sublimation have been investigated, and the seasonality has been presented at both study sites. In taiga region of eastern Siberia, sublimation from snow surfaces differed with atmospheric stability. During early spring, a significant difference in snow sublimation was observed between slopes and valley bottoms, despite variable vegetation cover. However, during observation period, only one episode of significant snow sublimation was observed, which was caused by strong wind and ensuing light snowmelt. As atmospheric stability decrease, the effect of forest cover on snow sublimation was clear, with a significant difference between forested areas and open fields. Later in the spring, increased net all-wave radiation did not lead to an increase in sublimation. The effect of forest cover on snow sublimation can be seen from the estimated bulk transfer coefficient for latent heat. The bulk transfer coefficient was larger for a larch forest than that of open site. At two study sites, sublimation shows similar seasonal variation, even if the snow depth varied differently. Peak sublimation was occurred earlier spring coupling light snow melting. Modeling works demonstrated sublimation proportioned 17 to 52% to winter precipitation. Key words: Northern Eurasia, snow cover, sublimation