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[MIS01-P07] Variability in the range of extreme non-Gaussian anomalies of synoptic-scale meteorological parameters in the Northern Hemisphere for 1979–2018
Keywords:non-Gaussian anomalies, synoptic scale, probability distribution function, Northern Hemisphere
One of the methods for identifying of meteorological variables anomalies is to analyze the characteristics of the probability distribution functions (PDFs) and their spatiotemporal variability. Boundaries of range for non-Gaussian anomalies (ap and an - for positive and negative anomalies, respectively) were determined based on the condition of the multiple kurtosis of empirical PDF above the Gaussian PDF for the same variable in the extreme values area ap and an are deviations from the average value, normalized to the standard deviation [1].
According to [2], the significant contribution to the dynamics of anomalies belongs to atmospheric processes on a synoptic time scale (SV). The method for SV anomalies and ap and an boundaries calculation is described in [1].
Climate change observed during recent decades affects changes in both the average values of meteorological parameters and their anomalies. Moreover, their variability may have significant differences depending on the region. Anomalies were identified in the lower and the middle troposphere (850, 700 and 500 hPa) for each seasons over the period 1979-2018 for the following meteorological variables: air temperature (t), specific air humidity (q), zonal, meridional and vertical components of wind speed (u, v, w, respectively), and geopotential (z). The study was carried out both for the Northern Hemisphere as a whole and individually for its latitudinal zones: in the northern latitudes (60-90N), in the middle latitudes (30-60N) and in the southern latitudes (0-30N). Each latitudinal zone was additionally divided into sectors - 60 degrees of longitude (the European, the Siberian, the Far Eastern, the Pacific, the American, the Atlantic sectors).
The goal of the study is to analyze the spatiotemporal variability of the probability distribution function boundaries for non-Gaussian anomalies of meteorological parameters of the synoptic scale in different sectors of the Northern Hemisphere for the period 1979-2018. The obtained results will make it possible to assess the frequency of extreme anomalies at the beginning of the 21st century more accurately.
The variability of threshold values depends on the selected meteorological parameter, season and latitude. It was revealed that changes in the anomalies boundaries at indicated atmospheric levels are generally similar. For example, the average seasonal and latitudinal variability of an and ap for horizontal wind speed components anomalies are generally similar and the range of their variability: an - more or equal to -3 and less and equal than -2.5, ap - more or equal to 3 and less and equal than 4; it increases by 0.5 in the mid-latitudes of the Atlantic sector.
The largest range of boundaries variability was observed in the high latitudes of the European sector for geopotential anomalies (an - from -3.5 to -2.25, ap - from 3.5 to 5.5).
The revealed features should be taken into account when assessing the frequency of extreme anomalies at the beginning of the 21st century.
This research was funded by the Ministry of Science and Higher Education of the Russian Federation (project # 121031300154-1) and by the Russian Science Foundation (RSF), project # 21-71-10052 (https://rscf.ru/en/project/21-71-10052).
1. Loginov, S.; Moraru, E.; Kharyutkina, E.; Sudakow, I. Climatology of Synoptic Non-Gaussian Meteorological Anomalies in the Northern Hemisphere during 1979-2018. Climate 2024, 12, 8.
2. Petoukhov, V.; Eliseev, A.V.; Klein, R.; Oesterle, H. On statistics of the free-troposphere synoptic component: An evaluation of skewnesses and mixed third-order moments contribution to the synoptic-scale dynamics and fluxes of heat and humidity. Tellus 2008, 60 Pt A, 11-31.
According to [2], the significant contribution to the dynamics of anomalies belongs to atmospheric processes on a synoptic time scale (SV). The method for SV anomalies and ap and an boundaries calculation is described in [1].
Climate change observed during recent decades affects changes in both the average values of meteorological parameters and their anomalies. Moreover, their variability may have significant differences depending on the region. Anomalies were identified in the lower and the middle troposphere (850, 700 and 500 hPa) for each seasons over the period 1979-2018 for the following meteorological variables: air temperature (t), specific air humidity (q), zonal, meridional and vertical components of wind speed (u, v, w, respectively), and geopotential (z). The study was carried out both for the Northern Hemisphere as a whole and individually for its latitudinal zones: in the northern latitudes (60-90N), in the middle latitudes (30-60N) and in the southern latitudes (0-30N). Each latitudinal zone was additionally divided into sectors - 60 degrees of longitude (the European, the Siberian, the Far Eastern, the Pacific, the American, the Atlantic sectors).
The goal of the study is to analyze the spatiotemporal variability of the probability distribution function boundaries for non-Gaussian anomalies of meteorological parameters of the synoptic scale in different sectors of the Northern Hemisphere for the period 1979-2018. The obtained results will make it possible to assess the frequency of extreme anomalies at the beginning of the 21st century more accurately.
The variability of threshold values depends on the selected meteorological parameter, season and latitude. It was revealed that changes in the anomalies boundaries at indicated atmospheric levels are generally similar. For example, the average seasonal and latitudinal variability of an and ap for horizontal wind speed components anomalies are generally similar and the range of their variability: an - more or equal to -3 and less and equal than -2.5, ap - more or equal to 3 and less and equal than 4; it increases by 0.5 in the mid-latitudes of the Atlantic sector.
The largest range of boundaries variability was observed in the high latitudes of the European sector for geopotential anomalies (an - from -3.5 to -2.25, ap - from 3.5 to 5.5).
The revealed features should be taken into account when assessing the frequency of extreme anomalies at the beginning of the 21st century.
This research was funded by the Ministry of Science and Higher Education of the Russian Federation (project # 121031300154-1) and by the Russian Science Foundation (RSF), project # 21-71-10052 (https://rscf.ru/en/project/21-71-10052).
1. Loginov, S.; Moraru, E.; Kharyutkina, E.; Sudakow, I. Climatology of Synoptic Non-Gaussian Meteorological Anomalies in the Northern Hemisphere during 1979-2018. Climate 2024, 12, 8.
2. Petoukhov, V.; Eliseev, A.V.; Klein, R.; Oesterle, H. On statistics of the free-troposphere synoptic component: An evaluation of skewnesses and mixed third-order moments contribution to the synoptic-scale dynamics and fluxes of heat and humidity. Tellus 2008, 60 Pt A, 11-31.