MODERN CHANGES OF THE URBAN HEAT ISLAND IN MOSCOW

Abstract

According to the data of weather stations for the period 1991–2020, as well as radiometric measurements of the surface temperature TS of Moscow region by Terra and Aqua satellites for the period 2000–2020, the daily course and long-term changes of the urban ‘heat island’ (UHI) of Moscow in the field of both the air temperature T at a height of 2 m and the TS were studied. For the analysis of TS 1379 satellite images were selected for 21 years in clear and slightly cloudy sky, when the UHI analysis is possible. The average annual values of TS were obtained using their normalization for separate seasons. The daily course of Moscow UHI in the air is weakly expressed, especially when compared with the countryside not only of the city center, but also of its entire area: only the weakening of this phenomenon in autumn and in the pre-winter season (from October to December) is reliable. According to satellite data, the ‘surface UHI’ is marked by a maximum in June-July with the strongest vegetation development, a minimum in autumn when leaves fall, and intermediate values in winter and spring. The rapid growth of T took place in 1991–2020 both in Moscow and in rural areas with approximately the same speed. As a result, there have been no statistically significant directional changes in the UHI intensity both in the air and on the surface as a whole over the past 20–30 years. The probable reasons for the general stabilization of the UHI in Moscow are both natural and socio-economic factors: the approximate constancy of the probability of clear weather (which promotes the strengthening of this phenomenon) and the vegetative activity in the region (which determines heat losses due to transpiration by plants), slowing down and stopping the growth of the population and energy consumption of the city, as well as its deindustrialization. Additional reasons are the gradual relocation of residents to the new outskirts of Moscow, as well as quarantine restrictions due to the COVID-19 pandemic in 2020.