South Atlantic sea surface temperature anomalies and air-sea interactions: stochastic models

Data on the South Atlantic monthly sea surface temperature anomalies (SSTA) are analysed using the maximum-entropy method. It is shown that the Markov first-order process can describe, to a first approximation, SSTA series. The region of maximum SSTA values coincides with the zone of maximum residual white noise values (sub-Antarctic hydrological front). The theory of dynamic-stochastic climate models is applied to estimate the variability of South Atlantic SSTA and air-sea interactions. The Adem model is used as a deterministic block of the dynamic-stochastic model. Experiments show satisfactorily the SSTA intensification in the sub-Antarctic front zone, with appropriate standard deviations, and demonstrate the leading role of the abnormal drift currents in these processes.     

Assessment of the statistical significance of global changes in the annual river runoff in XXI century due to possible anthropogenic warming of climate

A number of uncertainties of forecasts of changes in the annual runoff depths at global scale, obtained using information on results of integration of 21 IPCC climate models is studied. Following possible errors of these forecasts are calculated: errors of models; differences between main (IPCC) scenarios of emission of greenhouse gases in the atmosphere and resultant changes of global temperatures; mistakes in estimates of average long-term observed values of the runoff depths for the “control” period. Global maps of a “significance index” of forecasted changes in the runoff depths (estimations of changes in the annual runoff depths divided by mean square root values of errors of these estimations) for 2025, 2050, 2075 and 2100 are presented. It is shown that the most significant global changes of the runoff depths (growth in the north of Eastern Siberia, of the Russian Far East, of North America, falling in the “Greater Mediterranean Region”) are predicted for the second quarter of 21st century. Further changes of the runoff amplify only in the Amazon basin (reduction, by 2075). Almost everywhere else (including almost all European territory of Russia, Western Siberia, south of Eastern Siberia and of the Far East) the significance of changes in the runoff depths during 21st century is negligible.     

On the Effect of Intermittent Nonstationarity of Long-Term Changes in the River Runoff

Water Resources - Based on the analysis of 162 longest (more than 100 years each) series of annual, maximal, and minimal runoff in rivers of different genetic types, the regularities of changes in...     

The issue of global warming and changes in the runoff of Russian rivers

Maps of a series of characteristics were calculated and constructed for RF territory, including mean values of changes in runoff depths (evaluated by the main climate models of the Intergovernmental Panel on Climate Change) due to greenhouse effect estimated for 2040–2070; root-mean-square deviations from these values; relative errors of the estimates; mean values of changes in the runoff depth for different scenarios of greenhouse gas emissions; absolute and relative deviations of these values from their means for scenarios and integration of models. Chronological forecasts of possible changes in the mean runoff values for the rivers of Volga, Northern Dvina, Pechora, Ob, Yenisei, Lena, Yana, Indigirka, Kolyma, and Amur up to 2100 are calculated, and the root-mean-square errors of these characteristics are evaluated for the maximum number of uncertainties in the forecast. The greenhouse effect is shown to be less significant, other factors being the same, for rivers with small drainage basins and rivers with small modulus of flow.     

Statistical Modeling of the Global River Runoff Using GCMs: Comparison with the Observational Data and Reanalysis Results

Water Resources - Specific methods are proposed to assimilate the results of the “historical” experiments on 28 climate models. The results of the analysis confirm the hypothesis...