Russian Meteorology and Hydrology

Periodical surface currents with the periods of 46.5, 61, and 91 days detected from the satellite data in the Tatar Strait and Sakhalin Bay are presented as an effect of the Amur River runoff transformation in the estuary. The estuary transforms the flow as a flip-flop directing the Amur runoff by turns to the Sea of Japan or to the Sea of Okhotsk. The flip-flop period is six months. From May 23 to November 10, the Amur River flows into the Sea of Okhotsk and from November 10 to May 25, into the Sea of Japan.

A new method of medium-range forecasting of a class of fire hazard is developed based on more precise accounting of accumulated moisture deficiency that is reflected by the Nesterov standard index. A physico-statistical interpretation of hydrodynamic forecasts of fields of meteorological variables is used for finding of prognostic values of the elements of the fire hazard index, using forecasts of maximum air temperature and precipitation in the Novosibirsk region from the earlier developed scheme. The initial set of variables contains data on the isobaric surface geopotential at 500 hPa, surface pressure, temperature at 850 hPa at the regular grid points at 2.5° × 2.5° resolution and their derivatives. For formulation of forecasting equations, the algorithm of model self-organization is used with external criteria. The input of initial information, forecast issuance, displaying results and their delivery to customers based on GIS-technologies are totally automated.

Kinetics of the air bubbles exhalation process, which occurs in overcooled cloud drops when they hit the hail or graupel particles surface. Analytical relationship between a number of bubbles generated in a drop and their size depending on the degree of overcooling of cloud drops is revealed. It is shown that the air bubbles exhalation, which accompanies the coagulation growth of hail particles, occurs on the principle of “ebullition” of the liquid on the surface of a hail particle.

The analysis of experimental results characterizing the peculiarities of the radionuclide distribution in the dry aerosol sink is presented. An estimate is given of the specific activity of artificial and natural radionuclides in the sink of dry aerosols coming to the forest ecosystems.

The characteristics of spatiotemporal variability of surface air temperature anomaly fields in China are computed from the data of instrumental observations carried out from 1907 to 2000. The fields are represented by their empirical orthogonal function expansion. The temporal variations of the coefficients of this expansion are considered at the scale range from one month to five years. It turned out that both the orthogonal function structure and the type of the temporal variability of expansion coefficients in China differ from those in Northern Eurasia. Investigating the current climate warming in China, it is enough to consider the first two empirical orthogonal functions of temperature fields only. The characteristic time of the existence of temperature anomalies described by these functions is almost the same as that of the temperature anomalies in Northern Eurasia described by the first empirical orthogonal function of the respective fields.

Radar observations of the evolution and hierarchy of Cb clouds in different regions of the Earth are generalized to present the concept of a life cycle of a mesoscale convective system; during the life cycle, the separate Cb clouds develop into hierarchic coordinated mesoscale clusters, which recurrently originate and are localized in fixed places in the system which moves as a unit. The rising dominant clusters generate quasi-periodic oscillations of maximum intensity and wavelike space structure of the precipitation field. The methodological principles of the concept are used for objective classification of precipitation systems based on morphological and evolutional features. They can be used in techniques of very-short-range forecasting of hazardous convective weather.

Application of information about the historical maxima in hydrological computations allows one to improve design hydrological performances and to pass in some cases from extrapolation to interpolation as a more reliable solution. In this paper, an analytical solution is given for a task of determination of empirical probabilities and parameters of distribution function taking into account any historical maxima, which are located inside as well as outside the time series of observations and for their mixed location. For particular case studies, an advantage of consideration of the historical maxima is shown in comparison with computations without these maxima. It has also been shown that the exponential function between maximum discharges in order of their reduction and ordinates of standard normal distribution are effective enough for fitting the upper part of empirical distribution function.

Studied is the dependence of the frequency of severe weather phenomena (the wind and precipitation) on the altitude of the location of meteorological stations above the sea level for the period from 1984 to 2009. Obtained is the station distribution of probability of the formation of the mentioned phenomena for the warm and cold seasons.

Seasonal annual (Sa) and seasonal semiannual (Ssa) fluctuations are the dominant feature of long-period sea level variability in the Baltic Sea. Long-term series of observations (monthly mean sea level data) from the PSMSL database are used to estimate amplitudes and phases and to reveal spatial and temporal variations. It was found that the variations of seasonal amplitudes were quite significant from year to year and synchronous both within the Baltic Sea and in the Kattegat and Skagerrak straits. Climatologically averaged amplitudes and phases were calculated from 74 tide gauges, and the maps of spatial variability of seasonal constituents are plotted. The annual harmonic of the sea level gradually increases from the entrance (Danish Straits) to the heads of gulfs. The maximum amplitude of 12.7 cm is observed in the heads of the Gulf of Finland and Gulf of Bothnia. It is revealed that seasonal fluctuations in the Baltic Sea are caused by the zonal wind component.

Weather hazards caused by the vertical air movement are considered. It is stated that the only effective mean for their detection is the weather radar. The methods used for this purpose in modern radiolocation are listed, and the difficulties encountered in their practical implementation are discussed. A new method developed by the authors to detect the zone of local vertical movement of elementary reflectors is proposed. It is based on comparing the energy spectrum width of the output signal in the phase and amplitude detection channels.