Factors of the formation of extreme surface air temperatures during the 2010 heatwave in European Russia

Abstract

The summer 2010 heat wave, which lasted from late June to mid-
August and was characterized by maximum temperatures in Moscow exceeding
+38°C, represents the most extreme event in terms of both duration and
temperature over the European Territory of Russia (ETR) in the entire history of
instrumental observations. However, both the mechanisms responsible for the
formation of the long-lived blocking anticyclone and the factors leading to
extremely high temperatures during this heat wave remain not fully understood.
This study analyzes the surface heat flux balance as well as the components of the
temperature tendency equation within the atmospheric column in the center of the
heat wave. It is shown that the temperature increase at the onset of the heat wave
was primarily associated with an anomaly of incoming shortwave radiation
reaching 70 W m⁻². During this period, the contribution of diabatic heating in the
near-surface layer to the local temperature tendency was 55%, while horizontal
advection accounted for 36%. The influence of available soil moisture on the
partitioning of energy between sensible and latent heat fluxes is demonstrated, as
well as the role of ground heat flux in the temperature evolution, which during
certain periods was comparable in magnitude to the sensible heat flux into the
atmosphere. The formation of maximum temperature values, in addition to
radiative factors, was mainly associated with the advection of warmer air from
regions located to the southeast. During the period of temperature maximum
(29 July – 4 August), 84% of the temperature increase was related to
advective processes. Differences in the dominant factors controlling air
temperature variability in the boundary layer and in the free atmosphere are also
identified.