Mongolian cyclones are the main baric formations that are associated with the transfer of heat and moisture to the territory of the Baikal region. Traditionally, the formation of Mongolian cyclones is associated with the development of high-altitude troughs and the outflow of Arctic air to the northern and central regions of Mongolia. Large-scale circulation factors of mobile cyclogenesis change in modern climatic conditions. Therefore, the study of synoptic processes and meteorological factors during the formation of Mongolian cyclones in different time periods was carried out. Particular attention was paid to the study of the conditions for the formation of large floods during the emergence of southern cyclones in the Baikal region. Correlation analysis with variations in the climatic indices of the Northern and Southern Hemispheres was carried out to study the possible influence of oceanic processes in the development of mobile cyclogenesis on the territory of Mongolia.
A comprehensive climatic analysis has been carried out in the Mondy high-altitude station in the Eastern Sayan Mountains based on long-term data for the period 1948-2020. The anomalies of the average values of air temperature, atmospheric pressure, the amount of precipitation and the values of the fluxes of reflected radiation from the upper boundary of the clouds were calculated. The seasonal features of climate changes at different heights of the troposphere are revealed, the frequency of large anomalies of meteorological values is calculated. The periods of the year are highlighted, which significantly complicate astronomical observations over the high-mountainous regions of the Eastern Sayan Mountains in the modern period.
The tropopause is an important object of the circulation regime of the upper atmosphere, the temperature and wind characteristics of which can affect the processes in the middle and lower troposphere. Jet streams often pass near the tropopause level, which affect the transport and propagation of atmospheric pollutants. The paper analyzes the seasonal features of the wind regime at the tropopause level in the southern regions of Irkutsk region. It was revealed that the observed climate changes in Irkutsk region are closely consistent with changes in the meridionality of flows and wind speed at altitudes. The increase in the contribution of the southern winds during the warm season should be considered when assessing the ecological state of the region, especially during periods of dust storms in Mongolia and China.
The paper is devoted to large-scale and zonal atmospheric factors of climate variability over the territory of the Baikal region. This territory is considered to be one of the regions with highest rates of climate change according to Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet). The investigation was made of high- and low-frequency components in multidecadal timescales of climatic indices dynamics on the basis of trend, correlation, and spectrum analyses. The climatic indices determine and distinguish variability in pressure fields and geopotential at high latitudes in the Northern hemisphere, in the northern parts of the Atlantic and Pacific oceans throughout the time period of 1950–2017. Particular emphasis was put on searching for causes of increasingly arid climate in the Baikal region in summer months of 2000–2017, when the number of forest fires in the region rose dramatically. Winds having a southerly component at the height of middle troposphere were identified as the contributing factor for enhancing heat advection.
The calculations of the anomaly criteria for average annual values of air temperature at the Earth's surface in the European, Siberian and Far Eastern sectors for the period 1948-2018 have been performed according to NCEP / NCAR Reanalysis. Changes in the criteria for temperature anomalies near the Earth's surface and at altitudes of isobaric surfaces of 850 hPa (lower troposphere), 500 hPa (middle troposphere) and 300 hPa (upper troposphere) are analyzed. The results indicate an increase in the degree of temperature variability in the period 2007-2018 and increasing the area of the territory with an anomalous distribution of average temperatures. Also, good agreement was found on changes in temperature anomalies in the regions.
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