ИСТИНА

The ‘surface urban heat islands’ (SUHI) in Moscow and smaller localities in Moscow region have been studied in the surface temperature TS field by the data of long-living ‘Aqua’ and ‘Terra’ satellites supplied by MODIS radiometers during 2000÷2020. It was found that the SUHI intensity (ΔTS) does not depend on a size of outer rural zone around the city in the range from 45 to 140 km (for smaller zone ΔTS is underestimated due to dense belt of suburbs). Numerical experiments were carried out by step-by-step removing cells imitating clouds from image and ΔTS recalculation. If the cloud cover is ≤20% of the city area and ≤50% of the region area, displacement in ΔTS is small (±0.2 of the value under clear sky). Following this result, 1379 images during 21 years have been accepted for the analysis. The mean-annual ΔTS in Moscow is 2.6 ºC. The annual course of ΔTS is noted by maximum in June-July (~4.0ºC) and minimum in November (0.7ºC). Comparison with weather stations’ data demonstrates that ΔTS in daytime hours of satellite flight is about three times smaller than the mean daily value. On the other hand, ΔTS derived from satellite data is overestimated by ~40% due to the impact of anticyclones which allow analyzing images but enhance the SUHI. Besides Moscow, SUHI of nine smaller localities were also studied: ΔTS varies from weakly negative for small villages, close to zero for the smallest towns (Vereya), and up to 2.6°С. According to Landsat data, ΔТS >0°С even in the smallest settlements. The ΔTS depends on both the population (ranging from 101 to 107 ppl.) and the area of settlements (from 10–1 to 103 km2) as exponential functions.