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.
On the base of numerical experiments with the general circulation climatic model MIROC-ESM and climate model of intermediate complexity IAP RAS CM it was shown that the sign of the time lag between changes in global temperature T and atmospheric carbon dioxide content qCO2 depends on the type and the time scale of the external forcing applied to the Earth system. In particular, modern climate models are able to reproduce the qCO2 lagging behind T under conditions that are valid for the pre-industrial Holocene, so it does not contradict the idea of the importance of anthropogenic contribution to modern climate change.
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%.
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