A Cases Study Of Mongolian Cyclogenesis During The July 2018 Blocking Events

Abstract

Mongolia and Transbaikalia (M-TB) have experienced severe drought over the past 20 years due to the increased frequency of anticyclogenesis. However, in the summer of 2018, as a result of the formation of a series of cyclones over Mongolia and their move to the Transbaikalia, abnormally high precipitation was observed in the M-TB region. The dynamics of long Rossby waves and atmospheric blocking in the middle and upper troposphere were investigated to identify the causes of cyclogenesis over Mongolia. It was revealed that a sequence of events predefined the extreme precipitation in M-TB in the 2018 summer – the intensification of heat flux over the North Atlantic while maintaining cyclonic vorticity over Central Europe, the development of blocking ridges in the Urals and the Russian Far East, and an upper-level trough oriented to the eastern regions Mongolia. For a long time, the persistent advection of cold air in the rear part of the upper-level trough, as well as increased heat advection during the activation of the East Asian summer monsoon, caused meridional oriented upper-level front strengthening over the eastern regions of Mongolia and extreme precipitation.