Thermal Regime of Snow Cover in Winter in The High-Mountainous Part of Elbrus According To Observational Data and Modeling Results

• Published in: Journal of Biogeography
• Main Authors: E. Drozdov D., D. Turkov V., P. Toropov A., A. Artamonov Yu., Е. Дроздов Д., Д. Турков В., П. Торопов А., А. Артамонов Ю.
• Other Authors: For a significant contribution to the field research is expressed gratitude to the employee of the Faculty of Geography of Lomonosov Moscow State University, Ph. D. A.A. Polyukhov, as well as students of the Department of Meteorology and Climatology of Moscow State University Yu.I. Yarynich, A.S. Melik-Bagdasarova and R.R. Gibadullin. Field measurements were carried out with the financial support of the RFBR grant 20-05-00176. The results of the SPONSOR modelling obtained withing the framework of the research project ААААА19-119022190173-2 (FMGE-2019-0009) of the Research Plan of the Institute of Geography of the Russian Academy of Sciences., За существенный вклад в ход полевых исследований благодарим сотрудника географического факультета МГУ им. М.В. Ломоносова, к.г.н. А.А. Полюхова, а также студентов кафедры метеорологии и климатологии МГУ им. М.В. Ломоносова Ю.И. Ярынич, А.С. Мелик-Багдасарову и Р.Р. Гибадуллина. Полевые измерения и их анализ выполнены при финансовой поддержке гранта РФФИ 20-05-00176. Работы с моделью SPONSOR выполнены в рамках темы Государственного задания Института географии РАН АААА-А19-119022190173-2 (FMGE-2019-0009).
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: IGRAS 2023
• Subjects: mountain glacier;observations;numerical modeling;SPONSOR;Elbrus;Garabashi Glacier; горное оледенение;данные наблюдений;численное моделирование;SPONSOR;Эльбрус;ледник Гарабаши; Annals of Glaciology; The Cryosphere
• Online Access: https://ice-snow.igras.ru/jour/article/view/1222; https://doi.org/10.31857/S2076673423020059

Based on the analysis of the results of two measurement episodes in February 2021/22 and calculations using the LSM SPONSOR model, we obtained estimates of the variability of the snow surface thermal balance components and the thermal regime of the snowpack in the ablation zone of the Garabashi glacier on the southern slope of Mount Elbrus at 3850 m above sea level. A quantitative assessment of the sensitivity of the heat balance components to variations in key physical parameters has been performed. It is shown that the optimal value of the emissivity coefficient of snow cover in mountainous areas is 0.98: the absolute error in calculating the radiation temperature of the snow surface at this value does not exceed 1°С, in addition, the model adequately reproduces the thermal regime of deep layers of snow cover. It is also shown that a change in snow density by ±100 kg/m3 can lead to deviations in the temperature of the snow mass by several degrees. This indicates an urgent need to solve the methodological problem of measurements with thermocouples, in which the integrity of the snow mass is inevitably violated. A good agreement between the results of calculations of turbulent sensible heat fluxes in the SPONSOR model with direct measurements (correlation coefficient > 0.9) is demonstrated. Based on the measurement data, the fact of a fairly high frequency of high values of turbulent fluxes under conditions of intense radiative heating in combination with high wind speeds was revealed, which apparently turns out to be typical for high-mountain regions in winter (unlike the plains). For cases of strongly stable stratification in the surface layer, the model systematically overestimates the absolute values of heat fluxes. This may be due to the well-known problem of implementing the calculation scheme based on the Monin-Obukhov theory under conditions of temperature inversions. The inaccuracy in determining the snow surface roughness parameter, which in high mountain conditions is characterized by significant ...