The study deals with the analysis of the spatial and temporal variability of cumulonimbus cloud base height in Western Siberia based on ground remote (laser) sensing data at civil aviation meteorological stations during the period 2010–2021. The seasonal variability of the average values of the cumulonimbus base height was obtained, maps of its spatial distribution were constructed. It was established that an increase these values was occurred when moving from the north to the south of the region. Here the seasonal variability with a summer maximum was pronounced, there is also a second maximum in the winter months in the central part. Statistical characteristics of the cloud base height and its dependence on the station altitude were calculated. In addition, the analysis of atmospheric instability indices and convective precipitation was also carried out.
In the framework of the study, a comparative analysis of information on the cloud base height for the territory of Western Siberia based on the ERA5 reanalysis data and visual observations at weather stations is carried out for the period 2000- 2020. Spatial distribution maps were constructed, and a comparative analysis of spatial and temporal variability was carried out. The variability in cloud base height of vertical development clouds is also estimated. Spatial distribution of the total cloud base height values from observational data, in general, shows the similarity in all seasons: it increases from north to south of the region. However, we obtain contradictory results as for temporal variability. Thus, for further investigations, it is also necessary to use other types of databases and to take into account additional meteorological parameters to derived more accurate estimations of cloud base height values.
For the first time estimates of the non-linear relationships between the fields of the extreme values of basic meteorological variables (> 3σ) were obtained for the Northern Hemisphere, and their trends were established for the beginning of the 21st century. An approach, based on the cumulant analysis of the probability distribution, has been developed. It allowed us to identify non-linear (non-Gaussian) climate systems and determining their characteristics. It was shown that in the areas of baroclinic disturbances, non-Gaussian processes were significantly manifested in the troposphere of the Northern Hemisphere in a significant part of the territory (80-90%) in spring and autumn and were realized in a group of 3-4 elements (including vertical wind component, humidity or temperature) with 3 - 4 orders of magnitude connection. The application of this method simplifies the calculation of non-linear links of meteorological variables for prognostic problems solution.
The features of the formation of anomalous weather phenomena in the conditions of the current climate were studied, trends were determined, and the territory of their maximum changes was revealed. It was shown that at the beginning of the 21st century the number of anomalies increased by 2 times in the middle latitudes of Siberia, which may be due to a change in the type of atmospheric circulation caused by a decrease in the sea ice extent in the Arctic Ocean. Identification of the interannual variability of cyclones and anticyclones characteristics with manual tracking of surface synoptic maps for Siberia showed that during 2012-2017 there was a significant increase in the number of baric formations with their simultaneous intensification, which may be associated with increased weather instability. In addition, the number of positive anomalies of the meridional and zonal wind speed increased. The number of anomalies of specific humidity and air temperature, as well as negative anomalies of the components of wind speed, on the contrary, decreased. Analysis of the correlation coefficients showed that the beginning of the 21st century was characterized by significant changes in the linear relationship between abnormal weather phenomena and the characteristics of baric formations.
The paper assesses the spatial and temporal variability of dangerous meteorological phenomena associated with wind, precipitation, thunderstorms, extreme temperatures in the Tomsk region. Observational and ERA-Interim reanalysis data with spatial resolution of 0.125°x0.125° over the period 1979-2017 were used. The characteristics of atmospheric circulation were also calculated, including the indices of global circulation and convective instability — CAPE and LIFT ones. In order to determine the prevailing mechanism in the formation of dangerous meteorological phenomena, an assessment of the degree of their relationship with the circulation characteristics was obtained
In the study statistical estimates of specific humidity and total water content of the atmosphere were calculated for the territory of West Siberia for cold and warm season over the period of 1979-2015 using reanalysis dataset. The research was carried out for the whole territory of West Siberia and separately for its northern and southern parts. It was obtained that air humidity changes correspond to temperature ones. It was also established that the influence of large-scale atmospheric circulation on the changes in humidity characteristics increases in the northern part of the region in cold season at the beginning of the XXI century.
In the framework of this study the analysis of spatio-temporal variability in atmospheric precipitation characteristics in West Siberia was carried out using observational data by means of comparison two time intervals: 1976-1998 – the period of intensive global warming and 1999-2015 – the period of slowdown in the temperature growth. Features in precipitation amount variability in the northern and southern parts of the territory during warm and cold periods of a year are also described. Thus, in the beginning of XXI century the tendency to atmospheric precipitation increase is observed. Furthermore, the highest statistically significant growth is in the northern part of West Siberia in warm period.
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