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Estimates of the influence of the Atlantic long-period oscillation (ALO) on the formation of droughts in Northern Eurasia were obtained using the results of numerical experiments with the ECHAM5 atmospheric chemistry general circulation model and the mixed layer ocean model. In general, the model results are consistent with the empirical estimates. [ABSTRACT FROM AUTHOR]

The article focuses on a research examining the influence of the Atlantic Multidecadal Oscillation (AMO) on formation of the anomalous regional regimes of near-surface temperature and precipitation in Northern Eurasia. It discusses the use of the findings of the numerical experiments with the ECHAM5 atmospheric general circulation model (AGCM) and a mixed layer ocean model. It concludes that the AMO can influence the changes in temperature, precipitation, and sea level pressure.

Numerical experiments with the ECHAM5 atmospheric general circulation model have been performed in order to simulate the influence of changes in the ocean surface temperature (OST) and sea ice concentration (SIC) on climate characteristics in regions of Eurasia. The sensitivity of winter and summer climates to OST and SIC variations in 1998-2006 has been investigated and compared to those in 1968-1976. These two intervals correspond to the maximum and minimum of the Atlantic Long-Period Oscillation (ALO) index. Apart from the experiments on changes in the OST and SIC global fields, the experiments on OST anomalies only in the North Atlantic and SIC anomalies in the Arctic for the specified periods have been analyzed. It is established that temperature variations in Western Europe are explained by OST and SIC variations fairly well, whereas the warmings in Eastern Europe and Western Siberia, according to model experiments, are substantially (by a factor of 2-3) smaller than according to observational data. Winter changes in the temperature regime in continental regions are controlled mainly by atmospheric circulation anomalies. The model, on the whole, reproduces the empirical structure of changes in the winter field of surface pressure, in particular, the pressure decrease in the Caspian region; however, it substantially (approximately by three times) underestimates the range of changes. Summer temperature variations in the model are characterized by a higher statistical significance than winter ones. The analysis of the sensitivity of the climate in Western Europe to SIC variations alone in the Arctic is an important result of the experiments performed. It is established that the SIC decrease and a strong warming over the Barents Sea in the winter period leads to a cooling over vast regions of the northern part of Eurasia and increases the probability of anomalously cold January months by two times and more (for regions in Western Siberia). This effect is caused by the formation of the increased-pressure region with a center over the southern boundary of the Barents Sea during the SIC decrease and an anomalous advection of cold air masses from the northeast. This result indicates that, to estimate the ALO actions (as well as other long-scale climatic variability modes) on the climate of Eurasia, it is basically important to take into account (or correctly reproduce) Arctic sea ice changes in experiments with climatic models. [ABSTRACT FROM AUTHOR]

Possible changes in various characteristics of precipitation (its amount, intensity, probability of days with precipitation, and its extreme regimes) in the regions of northern Eurasia in the 21st century are assessed. The data for the analysis were obtained from simulations using global climatic models: atmosphere-ocean general circulation model ECHAM5/MPI-OM and an intermediate-complexity model developed in the Institute of Atmospheric Physics, RAS. The simulations were performed for the SRES-A2 and SRES-B1 scenarios of anthropogenic emission of greenhouse gases into the atmosphere. The results obtained from models of two generations, i.e., ECHAM5/MPI-OM and ECHAM4/OPYC3, models were compared. Detailed analysis was performed for the basins of largest Siberian rivers, the Volga River, and the Caucasian region. [ABSTRACT FROM AUTHOR]