Abstract. In this study we describe the wind wave fields in the Black Sea. The general aims of the work were the estimation of statistical wave parameters and the assessment of interannual and seasonal wave parameter variability. The domain of this study was the entire Black Sea. Wave parameters were calculated by means of the SWAN wave model on a 5 × 5 km rectangular grid. Initial conditions (wind speed and direction) for the period between 1949 and 2010 were derived from the NCEP/NCAR reanalysis. According to our calculations the average significant wave height on the Black Sea does not exceed 0.7 m. Areas of most significant heavy sea are the southwestern and the northeastern parts of the sea as expressed in the spatial distribution of significant wave heights, wave lengths and periods. Besides, long-term annual variations of wave parameters were estimated. Thus, linear trends of the annual total duration of storms and of their quantity are nearly stable over the hindcast period. However, an intensification of storm activity is observed in the 1960s-1970s.

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The numerical model simulations of storm activity in the White, Baltic and Barents Seas were analyzed for the period from 1979 to 2015. In this paper the storm number of these seas was calculated. The connections of wind wave climate with indecies of large-scale atmospheric circulation such as NAO, AO and SCAND were estimated. Also, the future changes of wind wave climate were analysed.

Extreme sea storms are dangerous and a potential source of damage. In this study, we examine storm events in the Black Sea and Caspian Sea, the atmosphere circulation patterns associated with the sea storm events, and their changes in the present and future (2046)(2047)(2048)(2049)(2050)(2051)(2052)(2053)(2054)(2055)(2056)(2057)(2058)(2059)(2060)(2061)(2062)(2063)(2064)(2065) climates. A calendar of storms for the present climate is derived from results of wave model SWAN (Simulating WAves Nearshore) experiments. On the basis of this calendar, a catalog of atmospheric sea level pressure (SLP) fields was prepared from the NCEP/NCAR reanalysis dataset for 1961-2000. The SLP fields were subjected to a pattern recognition algorithm which employed empirical orthogonal decomposition followed by cluster analysis. The NCEP/NCAR reanalysis data is used to evaluate the occurring circulation types (CTs) within the ECHAM5-MPI/OM Atmosphere and Ocean Global Circulation Model (AOGCM) for the period 1961-2000. Our analysis shows that the ECHAM5-MPI/OM model is capable of reproducing circulation patterns for the storm events. The occurrence of present and future ECHAM5-MPI/OM CTs is investigated. It is shown that storm CTs are expected to occur noticeably less frequently in the middle of the 21 st century.

An initial investigation of recirculation is carried out for the coast of the Black Sea. The local mesoscale circulations (land-sea breezes, mountain and valley winds) in coastal areas are shown to be an additional risk factor in creating favorable conditions for air stagnation and accumulation of air pollutants in the surface atmosphere layer. Two types of annual recirculation patterns are revealed for northern and north-eastern coast of the Black Sea. Longterm changes in recirculation are investigated. It is shown that the recirculation parameter values remained quasistable until the mid-1970s. Since 1976Since -1977, steady intensification of recirculation in both winter and summer is identified.

Physically-based distributed modelling under changing climatic conditions has been carried out for the Northern Dvina River basin using the ECOMAG (ECOlogical Model for Applied Geophysics). The parameters of the model have been adjusted through calibration against runoff hydrographs observed for the period [2000][2001][2002][2003][2004][2005][2006][2007][2008][2009]. Validation of the model has been performed for the period of [1970][1971][1972][1973][1974][1975][1976][1977][1978][1979][1980][1981][1982][1983][1984][1985][1986][1987][1988][1989]. Both sensitivity analysis and scenario approaches (based on the CMIP3 projections) have been applied to assess possible hydrological consequences of climate change in the basin. It has been shown that for greenhouse gases emissions A2 scenario, averaged for 11 climate models, annual runoff will not change significantly for the future 50 years. But due to increasing of winter precipitation by up to 15%, the volume of flow in the flood period could increase by up to 20%. Earlier beginning of the flood season is expected because of rising of the air temperature.

Described is the second stage of the work (2011-2014) on the implementation and development of the COSMO-Ru system of nonhydrostatic short-range weather forecasting (the first stage of the implementation and development of the COSMO-Ru system is described in [7,8]). Demonstrated is how the research activities and ideas of G.I. Marchuk influenced modern methods for solving the systems of differential equations that describe atmospheric processes (in particular, the version of the Marchuk's splitting method is used to find the solution of the finite-difference analog of the system of differential equations in the COSMO-Ru model); it is shown how he contributed to the development of the methods of assimilation of meteorological information associated with the use of adjoint equations. Given is a brief description of the COSMO model of the atmosphere and soil active layer, the COSMO-Ru system, and research activities on this system development. words: COSMO-Ru sys tem of mesoscale nonhydrostatic short-range weather fore cast ing, Marchuk-Rober semi-implicit method

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