Vertical temperature gradients in the basin of Sayano-Shushenskoye Reservoir

Spring-summerriver runoff forecasts in Siberia are based on spatial distribution estimates of its major factors in the basin - snow cover, precipitationand air temperature. Vertical temperature gradients calculation in the mountains of Siberia during the snowmelt is the main purpose ofthis study. Of great interest is the air temperature distribution with altitude in the basin of Sayano-Shushenskoye Reservoir, featuring avariety of landscapes and a weak meteorological level of scrutiny. The territory in question is a complex system of mountain ranges andintermountain basins of the Altai-Sayan highlands, including the eastern part of the Altai, the West Sayan, the Tyva Basin, a large partof the Eastern Sayan Mountains and the Republic of Tyva Mountains. Currently, only 14 meteorological stations are located there at aconsiderable distance from each other, mainly in lowlands. The air temperature at the stations is observed at altitudes from 540 to 1400meters. Temperature measurement in the highlands is not implemented. All available information in the Middle Siberian Department forHydrometeorology and Environmental Monitoring was involved in order to obtain an objective assessment of air temperature distributionwith altitude. For each region in this basin high-rise dependencies on the monthly average air temperatures in spring and summerare made. The observed values were approximated by linear dependencies in accordance with the method of least squares. In April-Maythe lapse rate reaches a maximum due to the cooling effect of snow-covered slopes in comparison with the snow-free valley. Periodswith inversions reduce the calculated values of gradients in April. By June-July gradients generally decrease, approaching a value of0.6°C/100 meters. Basin temperature gradients increase is consistent with the general direction of reducing the atmosphere moisture.The lowest values are observed in areas close to the humidified ridge of the Western Sayan Mountains, the greatest - in the droughtyDarkhat valley within the MPR. Evaluation of the temperature regime of mountainous countries is accompanied by another challenge -setting the reference weather station, which is usually located in the river valley. The way of temperature calculation in mountains usingweights is given. Average monthly values of gradients by districts can be averaged by non-linear dependencies to get multiyear dailyvalues used in the practice of melting runoff forecasts. Accounting for the effects on the vertical gradient of changing weather types, thenature of the underlying surface, humidity and other factors, allows a high degree of objectivity when calculating the air temperature atall basin altitudes.

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