Long-term changes of short-wave components of the radiation balance of the earth’s surface according to actinometric observations in Russian regions

Along with data on radiation fluxes at the upper boundary of the atmosphere obtained from satellite observation programs, the tracking of various components of the radiation balance of the Earth's surface is high-stakes for the analysis of climate change. The structure of temporal variability of incoming radiation is very complex and contains a large contribution of long-period fluctuations due to both anthropogenic and natural causes.

The paper considers modern regional features of changes in the main components of the radiation balance of the Earth's surface (direct solar, scattered and total radiation) taking into account the observational data for 1961-2020. In addition, the results of the accompanying analysis of climatic changes in the characteristics of cloud cover on the territory of Russia are presented.

At present, the actinometric network of The Federal Service for Hydrometeorology and Environmental Monitoring includes more than 160 observation points, for which three types of programs are established: continuous observations (registration) of radiation fluxes (33 stations), urgent observations (76 stations), and a reduced program of observations of total radiation using integrators (92 stations). The current system of regular monitoring of the components of the radiation balance of the Earth's surface is based on the results of observations under the program of urgent observations.

Over the last twenty years, the total number of stations with the full program of actinometric observations has varied, although formally not very significantly. However, due to arbitrary changes in the observation programs, which were made without coordination with climatologists, many series were interrupted. At the beginning of the period, there was a tendency to reduce the programs of urgent observations with their partial replacement by observations with recorders. Subsequently, due to a shortage of instruments, the transition to urgent observations began again, and this also affected the stations with sufficiently long observation series with the use of recorders.

The noted structural features of the actinometric network, the ongoing modernization and gradual transition to the use of automated complexes make it relevant to consider the possibility of expanding the information basis for monitoring. The analysis of long-term changes in direct, diffuse and total radiation (monthly and seasonal sums) has shown that, despite the known systematic deviations, both urgent observations and the results of continuous registration in general provide reproduction of long-term changes in the considered components of the radiation balance of the Earth's surface on the territory of Russia.