Based on the NCEP / NCAR reanalysis data, the characteristics of seasonal variations in cyclonic and anticyclonic activity over the Baikal Basin in 1980–2016 were analyzed. The estimates for the latitudinal dependence of cyclonic and anticyclonic activity in the atmosphere for the longitude belt 98 °E — 112 °E (corresponding to the longitudinal extent of the Baikal Basin) are obtained. Comparison of the two periods - the end of the 20th century (from 1980 till 1994 — period I) and the beginning of the 21st century (from 2002 till 2016 — period II) - revealed a decrease in cyclonic and an increase in anticyclonic activity over the Baikal Basin in summer. At the same time, the intensification of winter cyclonic activity in middle latitudes and anticyclonic activity in higher latitudes was noted.
The contribution of dynamic and thermodynamic causes in changes of precipitation character in Northern Eurasia that is expressed in increase of convective and decrease of large-scale precipitation, is still undetermined. Here, we estimate influence of atmospheric circulation on various characteristics of convective and large-scale precipitation in Northern Eurasia using correlation and regression analyses. We estimate different measures for atmospheric circulation including frequency of cyclones and anticyclones, blocking duration, intensity of the main atmospheric centers of action. Correlation and regression analyses were carried out using nonparametric Mann-Kendall correlation and Theil-Sen estimator. We revealed local response of precipitation on circulation characteristics, which strength varies in space and time. For some regions and seasons, opposite responses for convective and large-scale precipitation were found. Therefore, changing character of precipitation over Northern Eurasia can partly be explained by dynamical factors. Nevertheless, the main reason for increase of convective and decrease of large-scale precipitation is presumably associated with thermodynamics factors, namely increase of surface air temperature and humidity that resulting in convective instability growth.
Current estimates of methane emissions from high-latitude wetland ecosystems have significant inter-model variation, one of the reasons for which may be the internal variability of atmospheric circulation. This paper analyzes the effects of internal atmospheric variability on variations in methane emissions from Western Siberia. For average annual emission values, the uncertainty rate associated with climatic noise was 10%, and for individual months, 7–35%.
Estimates of the tropospheric lapse rate γ and an analysis of its connection with the surface air temperature Ts in high
latitudes of the Northern Hemisphere for summer and winter are performed using monthly-mean data from the ERAInterim
reanalysis (1979-2014). According to the reanalysis data the lapse rate values increase from 4.7 K/km near the
pole to 5.3 K/km in subpolar latitudes in winter and from 5.3 to 6.1 K/km in summer.
The estimates of dγ/dTs in interannual variability are found positive over the most part of the Arctic from reanalysis data.
At the same time, a negative correlation between γ and Ts was found for the Atlantic sector of the Arctic in winter and for
the central Arctic in summer. It is also noted regional peculiarities in the connection of lapse rate with Arctic oscillation
for winter and summer.
A comprehensive intercomparison of midlatitude storm characteristics is presented. Extratropical storm characteristics were derived from 16 reanalysis-based objective automated algorithms for cyclone identification and tracking from the IMILAST project and from manual method based on an expert inspection of weather charts. The analysis was carried out for the Siberian region (50–80N, 60–110E) for two seasons (winter of 2007/08 and summer of 2008). Most of the automated algorithms show 1.5–3 times more cyclones and 3–5 times more cyclone tracks in the Siberian region compare to the manual method. The algorithms show a good agreement with the manual method for spatial distribution of cyclones and tracks number with spatial correlation coefficient varies around 0.8–0.9 in summer and around 0.7–0.9 in winter for most of the algorithms. Two ranking measures were used to evaluate similarity of objective algorithms with the manual method.
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