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Project titleRelationship between the formation of extreme precipitation in Southern Siberia and Rossby waves breaking and atmospheric blocking

AffiliationV.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science,

Research area 07 - EARTH SCIENCES, 07-601 - General circulation of the atmosphere and dynamic meteorology

KeywordsRossby waves, atmospheric blocking, precipitation, the southern part of Eastern Siberia, breaking, wave energy flux, synoptic disturbances, cyclone, anticyclone, teleconnection patterns, East Asian Summer monsoon

Annotation
In recent decades, the number of dangerous and unfavorable phenomena associated with atmospheric circulation has increased. There are several mechanisms leading to an increased likelihood of weather disasters associated with climatic variability due to an increase in carbon dioxide concentration. The most significant is the change in the wave processes of midlatitudes, which is expressed in the change in the characteristics of the Rossby waves breaking and atmospheric blocking. One of the key issues related to the growth of extreme weather processes is the issue of variability of atmospheric precipitation in the summer period, which is one of the main reasons for the formation of “flash floods”. A large number of researchers indicate an increase in the intensity of precipitation on the territory of Russia with an average lengthening period without rain. In June, July 2018 and 2019 record-breaking precipitation in the Chita and Irkutsk regions led to a flash flood in the rivers, which led to catastrophic consequences. In addition, since 2018, the end of the longest dry period (1996-2017) in the Lake Baikal basin has been recorded. Within the framework of the project, we aim to investigate the relationship between the formation of extreme precipitation in the south of Siberia and the most significant large-scale wave processes: the Rossby waves breaking and the formation of atmospheric blocking. The project is aimed at solving the fundamental problem of studying the mechanisms of formation of extreme precipitation in the south of Siberia, from the point of view of processes in the middle and upper troposphere and their variability in the period 1982-2019. Forecasts of precipitation and water content for the region and adaptation algorithms to a certain extent depend on the results of solving this fundamental problem.

Expected results
1. Catalog of events of the most extreme precipitation in the summer of southern Siberia for a long period of 1982-2019. Based on a study of the characteristics of the 2018/2019 events responsible for the formation of catastrophic “flash” floods in southern Siberia. 2. Contribution of breaking waves (stratospheric-tropospheric exchange) to the formation of the most extreme precipitation in southern Siberia, percentage, grouping of events according to the degree of intensity of processes. Estimates of vertical and horizontal mixing processes. Values of vertical velocities, baroclinic instability. The magnitude of moisture fluxes, and the answer to the question, what is the role of transport from the southeast (monsoon). 3. Synoptic features of wave breaking in the south of Siberia in accordance with the theory of two waveguides. Peculiarities of stratospheric (depth, intensity, streamer shape) and tropospheric intrusions, formation of cut-off cyclones, and blockings. Basic models (modes) of vorticity anomalies of two waveguides for the events under study. 4. Assessment of the contribution of wave chains of two waveguides to wave breaking associated with extreme precipitation in the center of Eurasia. 5. Regularities of the variability of events of extreme precipitation amount, wave characteristics, and their relationship. The results obtained will provide information on fundamental processes associated with the formation of precipitation, as well as wave processes. First of all, the importance and necessity of the development of these issues are associated with the insufficient explanation of the degree of the extremeness of precipitation processes in the south of Siberia. Also, the results obtained can help in the development of precipitation forecasts in the south of Siberia at different time scales. The quality of the forecast, in turn, directly depends on the measures to adapt the region to changes in precipitation and, accordingly, river runoff.

Annotation of the results obtained in 2023
The social and economic consequences triggered by floods in southern Eastern Siberia (ES) and the anticipated increase in extreme precipitation and floods in northern Eurasia have underscored the need to identify atmospheric circulation patterns, causing extreme precipitation in ES, as well as changes in these patterns. The study of instability and moisture transfers associated with the dynamics of potential vorticity (PV) for two periods: 1982–1998 and 1999–2019, has led to several conclusions. Extreme precipitation is characterized by an increase in the instability of the vertical atmospheric structure in the area of its occurrence, which is compensated by stability around this zone, with an intensification of moisture transport from the East Asian summer monsoon region. The PV field in subtropical regions and mid-latitudes shows an enhancement of positive and negative PV anomalies southeast and northwest of Lake Baikal, respectively. Contours of PV during periods of extreme precipitation take the form of cyclonic wave breaking (CWB) and closed cut-off low areas with high vorticity values. Extreme precipitation, accompanied by wave breaking, is characterized by the redistribution of areas of stability and moisture content. This can lead to the formation and maintenance of blocking and, consequently, the simultaneous occurrence of floods and droughts in neighboring regions, to some extent causing the previously identified dipole precipitation pattern over Mongolia and ES. Additionally, differences in the conditions governing extreme precipitation between the two periods have been detected, likely associated with changes in waveguides over Eurasia. For the later period from 1999 to 2019, there is a more pronounced intensification of meridional contrasts in potential vorticity and geopotential.

Publications

1. Antokhina O.; Antokhin P.; Gochakov A.; Zbirannik, A.; Gazimov, T Atmospheric Circulation Patterns Associated with Extreme Precipitation Events in Eastern Siberia and Mongolia Atmosphere, V.14, №3, P.480 (year - 2023) https://doi.org/10.3390/atmos14030480

2. Antokhina O.Y.; Antokhin P.N.; Belan B.D.; Gochakov A.V.; Martynova Y.V.; Pustovalov K.N.; Tarabukina L.D. ; Devyatova E.V. Effects of Rossby Waves Breaking and Atmospheric Blocking Formation on the Extreme Forest Fire and Floods in Eastern Siberia 2019 Fire, V. 6, №3, P. 122 (year - 2023) https://doi.org/10.3390/fire6030122

3. Antokhina O. Yu., Antokhin P. N., Gochakov A. V., Zbirannik A. A., Gazimov T. F. Динамика потенциальной завихренности умеренных широт и субтропиков для событий экстремальных осадков на юге Сибири Институт мониторинга климатических и экологических систем СО РАН, С. 7-11 (year - 2023)

4. Antokhina O. Yu., Antokhin P. N., Gochakov A. V., Zbirannik A. A., Gazimov T. F. Атмосферные циркуляционные паттерны, связанные с экстремальными осадками в Восточной Сибири и Монголии Институт физики атмосферы им. А.М. Обухова РАН, С.25 (year - 2023)

5. Zbirannik A.A., Antokhina O.Yu., Antokhin P.N. Особенности потока волновой энергии над Евразией перед событиями выпадения экстремальных осадков в июле 2010 года на юге Восточной Сибири ООО "Издательство ВВМ", С.223-227 (year - 2023)

6. Zbirannik A.A., Antokhina O.Yu., Antokhin P.N. Формирование экстремальных осадков на юге Восточной Сибири в период атмосферного блокирования над европейской территорией России в июле 2010 года Оптика атмосферы и океана. Физика атмосферы: Материалы XXIX Международного симпозиума. Электронный ресурс Томск: Издательство ИОА СО РАН, D. 98-103 (year - 2023)

7. - Исследование движений воздуха планетарного масштаба Маяк. Иркутск, - (year - )