Лëд и снег (May 2021)
Meteorological regime of the Sygyktinsky Glacier (the Kodar Ridge) during the ablation period
Abstract
Meteorological parameters measured over two months by two automatic weather stations on the Sygyktinsky glacier and its terminal moraine (Kodar ridge, South of Eastern Siberia, 56.9° N, 117.4° E) were used to study the physical processes controlling the summer ablation of the glacier. The meteorological regime of the glacial zone is conditioned by large-scale atmospheric circulation and characterized by steadily positive air temperatures (7.2±4.5 °C), high relative humidity (76±23%), significant cloud cover (66%), a predominance of low-intensity precipitation, and low wind speeds (1.0±0.8 m/s). It is found that the daily air temperatures on the glacier strongly correlate (r = 0.97) with those in the free atmosphere, so the ERA-Interim reanalysis data (at the level of 750 hPa) can be used to make longer the temperature series on the Kodar glaciers. We found significant statistical relationships between the daily ablation (29 mm day–1 on average) and relative humidity as well as with incoming shortwave radiation and cloud cover. The short-wave radiation balance (91 W/m2) is the main source of energy for melting, which depends on the albedo (average value 0.41). On days with summer snowfalls, the increase in albedo reduces the short-wave balance by 2.5 times. Explicit and latent heat fluxes are the secondary sources of melting energy, while heat loss takes place mainly due to effective long-wave radiation (–15 W/m2). The absorbed short-wave radiation on the glacier was smaller than that on the moraine, but the radiation balance was comparable on both sites owing to smaller effective LW radiation on the glacier. The dominance of the radiation factor demonstrates the important role of the solar radiation regime (cloud cover and atmospheric transparency) in the surface ablation of the Kodar glaciers.
