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The slope of the tropopause is calculated from the data of its height in the points of a regular grid. From the NCEP Reanalysis-2 for 1990-2007, the slope angles are calculated of the tropopause approximated by different constant values of Ertel potential vorticity within the latitude band of 30°-70°N. Effects of horizontal resolution of the data under use on the calculation results are studied on the basis of ten-day samples of objective analysis by UKMO, NCEP, and operative objective analysis of Hydrometeorological Center of Russia in different seasons of 2009.

In connection with analysis of anomalous weather in summer of 2010, the state-of-the-art is reviewed of climatology of the blocking anticyclones, of mechanism for their onset and persistence, as well as possibilities of their forecasting. The main results are quoted on occurrence frequency, intensity, and duration of blockings and on their connection with features of general circulation of the atmosphere in the Northern and Southern hemispheres. As the primary cause of the blocking formation, nonlinear instability of the Rossby waves is considered with intense energy exchange with planetary waves and with synoptic-scale eddies. Mathematical means have been developed to investigate the energy exchange on the real data of objective analysis (reanalysis). This approach can be applied to analyze causes of anomalous duration of the summer blocking. From the point of view of forecasting, blockings do not differ much from other atmospheric pressure systems. Namely, within the framework of medium-range forecasting, the blocking onset, under condition of its absence in the initial fields, can be predicted with a projection of several days; also, the ensemble forecasts are generally more successful than those obtained with any single model. The blocking duration and decay can be predicted successfully within the medium-range forecasting.

On the basis of objective analysis of meteorological fields and 12-h precipitation amounts observed at the stations in the former European USSR, statistical relationships are studied between the diagnostic characteristics of dynamic forcing of vertical motion and occurrence frequency of precipitation of different intensity ranges over the whole area and each of six separate regions. The following diagnostics are considered: frontal parameter as a measure of baroclinicity and of pressure field curvature; neutral buoyancy level as a measure of grid-scale convective instability; scalar frontogenetic function at the 850-hPa level and dynamic tropopause height as measures of intensity of vertical transverse circulations in unstable baroclinic zones. Informativity estimates are presented of each diagnostic and their pair combinations as precipitation predictors. The frontal parameter (in all seasons) and the neutral buoyancy level (in all seasons but winter) are significant as single predictors of precipitation. Among the pair combinations of the diagnostics, those which include the frontal parameter are more informative, and the combination of the latter and the neutral buoyancy level is the most informative one. A comparable informativity, under certain conditions, is demonstrated by the combinations of the frontal parameter with the frontogenetic function and with the tropopause height (in particular, in winter and fall for heavy and very heavy precipitation). In all the cases, the values of the informativity criterion (Pierce's index) are higher for more intense precipitation as a predictand.

A review of the papers dealing with various aspects of stratosphere-troposphere exchange (STE) is presented. The development of STE concepts is described and quantitative estimates of STE obtained by different authors are given. Typical time scales and geographic features of STE are described. Special attention is given to the specific features of STE at extratropical latitudes where active vertical air transport is observed in both directions. The air ascent through the tropopause occurs there in the zones of warm conveyor belts, and the air descent takes place in the zones of stratospheric intrusions. Exchange processes in the key region including the upper troposphere and the lowermost stratosphere are described. The mechanisms of large-scale stratospheric intrusions in the systems of tropopause folds or cut-off lows are presented as well as the mechanisms of the mixing of the stratospheric air with the tropospheric one. Specific features of deep stratospheric intrusions are discussed which are based on the analysis of such indicators of stratospheric air as high concentrations of ozone and stratospheric radionuclide 7 Be. Some aspects of stratosphere-troposphere energy exchange are considered. po sphere ex change, tropo pause, strato spheric in tru sions, fil a ments, ozone, strato spheric radionuclides, block ing, sud den strato spheric warm ing, waveguides