СПЕКТРАЛЬНЫЕ ХАРАКТЕРИСТИКИ ТУНДРОВЫХ И ЛЕСОТУНДРОВЫХ ЛАНДШАФТОВ В ГОДЫ ЛЕТНИХ ТЕМПЕРАТУРНЫХ АНОМАЛИЙ

Abstract

The warming at high latitudes, remaining in recent years, has a direct impact on arctic and subarctic landscapes. Possible changes of this landscapes under the climate warming are closely related with regulatory mechanisms for the underlying surface temperature. The circumstances of forming radiation and evapotranspirational regulatory mechanisms for the surface temperature were explored for tundra (from arctic to southern) and forest tundra landscapes of Novaya Zemlya and Western Siberia. The MODIS data of surface spectral characteristics were used, and more specifically albedo (Al) and surface temperature (Ts) for July 2000-2019. The work shows that the radiation regulatory mechanism of the surface temperature is dominated in glacial and polar desert landscapes of Arctic and Subarctic with a predominance of stony and rubble types of surfaces with lichens. At the same time, radiative surface temperature control mechanism in mountain and arctic tundra of Novaya Zemlya almost does not depend on weather anomalies and so far has a little implication for the temperature trend. In the mainland and forest tundra, the evapotranspirational regulatory mechanism for the surface temperature starts to prevail. This is supported by the increasing of monthly average air temperatures to 15-16°С, which is beneficial to the vegetation diversity. In subzones of the southern and forest tundra, the connection of albedo and surface temperature depends on altitudes, slope exposure and especially on extreme temperature anomalies. In basins, or hydromorphic complexes, in cold years against the backdrop of wetlands the regulatory mechanism for the surface temperature prevails, and in warm years the humidity decreasing leads to the highest vegetation development and the connection type can turn into the evapotranspirational one. On the high grounds the return process is observed, which is also connected with the changes in humidification conditions. In forest tundra, where the air temperature rises and the canopy height increases, the evapotranspirational mechanism of spectral parameters Al–Ts connections is weakening. As a result, in southern and forest tundra two balanced steady states of the connection types of surface spectral characteristics can exist in relation to lighting conditions and temperature anomalies.