Temporal and Spatial Patterns of Changes in Thermal Regime of the Rivers in the Northeast of the Asian Part of Russia. 2. Changes in the Heat Fluxстатья
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Дата последнего поиска статьи во внешних источниках: 1 мая 2024 г.
Аннотация:The thermal state of the northern rivers of Russia has undergone significant changes in the last 30-40 years due to climate warming, changes in water runoff. The purpose of this investigation is to study and explain only changes in heat flux, their long-term and spatial patterns in the northeast Asian part of Russia. Here, the heat flux of rivers is formed under the influence of climatic conditions, the altitude and latitude location of rivers, continuous permafrost, aufeis, glacial runoff and groundwater recharge, different water regime of rivers. An important feature of the research is the use of a large number of hydrological stations – 145 and 231 gauging stations with data on water discharge and stream temperature, mainly from 1955 to 2012/2018. The abundance of data enabled to create unique maps of heat-flux and its deviations from the values of the base period. Empirical relationships between heat flux, on the one hand, and water runoff and water temperature, on the other, made it possible to improve the initial data, showed the leading role of water runoff in long-term fluctuations in heat-flux. However, climatic warming enhances the role of the temperature factor and transforms the relationship between water runoff and heat-flux, "shifting" them upwards. So far, these violations have not covered most of the gauging stations. The long-term “behavior” of heat flux is not unambiguous. Nevertheless, the period since the late 1980s is distinguished by higher values of heat flux. 20% of gauging stations demonstrate an increase in heat, compared to the previous period, by 10%, 39% - an increase from 10 to 25%, 36% – >25%. Since the mid - second half of the 2000s, the heat flux of the rivers in the western part of the region has signs of stabilization and even a decrease. The reason is low water flow. A violation of the stationarity of the series in terms of dispersion (F-test) was found at 30% stations with reliable and long-term observations, mainly in the eastern part. Further changes in the heat flux of the regional rivers will depend on both changes in the river water flow and temperature. Within a year, almost all annual heat flux (90-95%) is generated in the summer months and has peaks in June and July. In the Vilyuy River basin, in the upper and middle part of the Kolyma River basin and on the coast of the Sea of Okhotsk, the proportion of summer months decreases to 65-90%. In addition to estimation of heat flux at the hydrological stations, the inflow of river waters into the mouths of the main rivers of the region and, in general, into the Arctic seas was assessed in various ways.