Accelerated loss of alpine glaciers in the Kodar Mountains, south-eastern Siberia

<p>The energy balance of a glacial surface and its melting is strongly controlled by altering synoptic processes in the lower troposphere. Therefore, classification of the processes of atmospheric circulation over the glaciarized regions is very important for better understanding of long-term trends in glacier changes. The glaciers of the Kodar Ridge (south Eastern Siberia) have shrunk in area by about 60% since the mid-19th century, with the largest decline taking place at the end of the 20th century. We have compiled the daily catalog of the weather types (WTs) from 1970 to 2020 based on the Jenkinson and Collison objective classification applied for the area (47.5&#8211;67.5&#176; N, 102.5&#8211;132.5&#176; E) centered over the Kodar Ridge. The gridded sea level pressure (SLP) and isobaric 700 hPa data was obtained from the National Center for Environmental Prediction / National Center for Atmospheric Research (NCEP/NCAR) reanalysis. In total, 26 WTs were identified and the frequency of different synoptic types was statistically analyzed. The most frequent group of WTs is advective (40%), followed by anticyclonic (34%) and cyclonic (14%). The unclassified type totally accounts for 13%. We revealed the differences between the frequency of synoptic processes in seasonal cycle and at different atmospheric levels (SLP and 700 hPa). Cyclonic weather types usually prevail in summer, while anticyclonic ones in autumn and winter. At 700 hPa level, the frequency of anticyclonic WTs increases in summer, while the frequency of advective types increases in all seasons. Over the past 50 years, the frequency of anticyclonic types demonstrates decreasing trend, while that of cyclonic and advective weather types increased (SLP data). In the 1980s and early 1990s the frequency of cyclonic WTs decreased, which could lead to a decrease in cloud cover over the Kodar region and an increase in net radiation of glacier surfaces. This study was supported by the Russian Foundation for Basic Research (project No. 19-05-00668).</p>

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Surface energy balance of the Sygyktinsky Glacier, south Eastern Siberia, during the ablation period and its sensitivity to meteorological fluctuations

Scientific Reports ◽

10.1038/s41598-021-00749-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Eduard Y. Osipov ◽

Olga P. Osipova

Keyword(s):

Energy Balance ◽

Wind Speed ◽

Surface Energy ◽

Surface Energy Balance ◽

Heat Fluxes ◽

Shortwave Radiation ◽

Eastern Siberia ◽

Atmospheric Conditions ◽

South Eastern ◽

Glacier Ablation

AbstractThe physically based melt of the low elevation Eastern Siberian glaciers is poorly understood due to the lack of direct micrometeorological studies. We used an automatic meteorological station to record the meteorological and energy characteristics of the Sygyktinsky Glacier, south Eastern Siberia (56.8° N, 117.4° E, 2,560 m a.s.l.), during two ablation seasons and computed the surface energy balance (SEB) for 30-min intervals. The glacier ablation was both modeled and measured by stakes and a thermistor cable. The net radiation (Rnet) was the main contributor (71–75 W m−2, 89–95%) to the SEB (79 W m−2, 100%), followed by sensible (2–4 W m−2, 3–5%) and latent (2–3 W m−2, 2–4%) heat fluxes. The net shortwave radiation was the main positive component of Rnet, while the net longwave radiation was weak and either negative (− 15 W m−2 in 2019) or positive (4 W m−2 in 2020). The small proportion of turbulent fluxes in the SEB is explained by the low wind speed (1.2 m s−1). The glacier ablation was found to be more sensitive to changes in shortwave radiation and wind speed, suggesting the need to consider the atmospheric conditions of the ablation period (summer snowfalls, cloudiness, wind speed) when analyzing long-term trends in glacial changes.

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