印度东南部海岸拉梅斯沃勒姆滨外保克湾底层水特征对底栖有孔虫的影响

有孔虫生活在海洋和半咸水环境。底栖有孔虫的存在很大程度上受物理因素（深度、温度、光量、水体扰动）、化学因素（盐度、溶解氧和可用元素）和生物因素（食物供给量和底层沉积物特征）的制约。研究人员对印度东、西岸现代底栖有孔虫生态学和分布状态进行了研究。Ｎａｉｄｕ等在对Ｖｉｓａｋｈａｐａｔｎａｍ港复合体有孔虫进行分析后提出 ,可以将有孔虫作为海洋污染的指示物。ＳｒｅｅｎｉｖａｓａＲａｏ等采用Ｑ模式系数分析对尼赞伯德讷姆湾有孔虫的分布进行了研究 ,确认此区域存在４种组合 ,受不同环境条件的影响。Ｋｈａｒｅ等对门格…     

Raising the packing density of computerized oceanographic data records

In this paper the peculiarities of compiled oceanographic data sets, which consist primarily in the presence of some characteristic information as well as in the planned incomplete filling of the files with observations, are discussed. A number of special ways are suggested which essentially improve the packing density of computerized data without applying special archiving algorithms. The effectiveness of these methods has been tested by treating thein situ hydrological/chemical data file compiled in the Black Sea in 1988.Translated by Vladimir A. Puchkin.     

Effect of ice cover on oscillations of fluid in a closed basin

Within the framework of the linear theory of long waves, the problem of the effect of ice cover on seiche oscillations of fluid in a two-dimensional constant-depth basin is solved. The eigenfrequencies and eigenfunctions of seiche oscillations are obtained for different boundary conditions at ice edges: rigid coupling and free edges. The forced oscillations of fluid and ice under the action of a moving disturbance of atmospheric pressure are investigated. The change in the stress of ice bending is considered and it is shown that the coast ice can be broken.     

Transformation of black-sea waters in the Sea of Marmara

The analysis is performed on the basis of comparison of the hydrological characteristics of prestrait regions of the Sea of Marmara. It is shown that, in summer, the Black-Sea waters are weakly mixed with the Mediterranean waters and the levels of salinity in the prestrait regions differ by 0.6–0.9‰. In winter, the indicated difference increases and the level of salinity near the entrance of Dardanelles reaches 29‰ and exceeds the level observed near the entrance of Bosporus by 5.5‰. In the analyzed regions, we observe local temperature maxima and minima near the interface of two water masses. This is explained by the presence of strong seasonal variations of temperature for the Black-Sea waters and their absence for the Mediterranean waters. The physical mechanisms responsible for the seasonal variations of the intensity of transformations of the Black-Sea waters are discussed. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 49–55, March–April, 2007.     

Dynamics of climate extremes in northern Eurasia in the late 20th century

Changes in climatic parameters and in temperature and precipitation extremes in northern Eurasia in the late 20th century are analyzed. A spatial distribution of temperature and precipitation anomalies and of a set of indices of climate extremes is presented. Changes in climate extremes show a tendency toward a milder climate, mainly in winter. At the same time, the frost-free period has substantially decreased in the eastern, northern, and central parts of European Russia. In some regions during summer, there is an increase in the frequency of extreme events such as heavy rains, droughts, and sharp cooling. It is shown that the geographic pattern of present-day climate anomalies is linked to variations in the large-scale atmospheric circulation. The main mechanism of the current warming in northern Eurasia is a winter intensification of zonal flow linked to the increased frequency of positive anomalies of the North Atlantic Oscillation index.     

Parameter sensitivity of three Kalman filter schemes for assimilation of water levels in shelf sea models

In applications of data assimilation algorithms, a number of poorly known assimilation parameters usually need to be specified. Hence, the documented success of data assimilation methodologies must rely on a moderate sensitivity to these parameters. This contribution presents a parameter sensitivity study of three well known Kalman filter approaches for the assimilation of water levels in a three dimensional hydrodynamic modelling system. The filters considered are the ensemble Kalman filter (EnKF), the reduced rank square root Kalman filter (RRSQRT) and the steady Kalman filter. A sensitivity analysis of key parameters in the schemes is undertaken for a setup in an idealised bay. The sensitivity of the resulting root mean square error (RMSE) is shown to be low to moderate. Hence the schemes are robust within an acceptable range and their application even with misspecified parameters is to be encouraged in this perspective. However, the predicted uncertainty of the assimilation results are sensitive to the parameters and hence must be applied with care. The sensitivity study further demonstrates the effectiveness of the steady Kalman filter in the given system as well as the great impact of assimilating even very few measurements.     

Electronic atlas of the Russian Arctic coastal zone

A set of digital maps including geology, Quaternary sediments, landscapes, engineering-geological, vegetation, geocryological and the series of regional sources have been selected to characterize the Russian Arctic coast. Based on this data, new maps of engineering geocryological zoning and zoning of the coast with respect to the intensity of exogenous geological processes and risk of technogenic impacts have been generated at the scales of 1:4,000,000–1:8,000,000. These maps are a tool to assess the impact of industry on the Arctic coast of the country.     

Variation in microbial biomass and community structure in sediments of peter the great bay (sea of japan/east sea), as estimated from fatty acid biomarkers

Variation in the microbial biomass and community structure found in sediment of heavily polluted bays and the adjacent unpolluted areas were examined using phospholipid fatty acid analysis. Total microbial biomass and microbial community structure were responding to environmental determinants, sediment grain size, depth of sediment, and pollution due to petroleum hydrocarbons. The marker fatty acids of microeukaryotes and prokaryotes - aerobic, anaerobic, and sulfate-reducing bacteria -were detected in sediments of the areas studied. Analysis of the fatty acid profiles revealed wide variations in the community structure in sediments, depending on the extent of pollution, sediment depth, and sediment grain size. The abundance of specific bacterial fatty acids points to the dominance of prokaryotic organisms, whose composition differed among the stations. Fatty acid distributions in sediments suggest the high contribution of aerobic bacteria. Sediments of polluted sites were significantly enriched with anaerobic bacteria in comparison with clean areas. The contribution of this bacterial group increased with the depth of sediments. Anaerobic bacteria were predominantly present in muddy sediments, as evidenced from the fatty acid profiles. Relatively high concentrations of marker fatty acids of sulfate-reducing bacteria were associated with organic pollution in this site. Specific fatty acids of microeukaryotes were more abundant in surface sediments than in deeper sediment layers. Among the microeukaryotes, diatoms were an important component. Significant amounts of bacterial biomass, the predominance of bacterial biomarker fatty acids with abundance of anaerobic and sulfate-reducing bacteria are indicative of a prokaryotic consortium responsive to organic pollution.     

Record-breaking chemical destruction of ozone in the arctic during the winter of 2004/2005

The extremely cold winter of 2004/2005 was accompanied by an intensive formation of polar stratospheric clouds and a significant chemical destruction of ozone. The results of calculating chemical losses of ozone in the polar cyclone from the SAGE-III satellite data are given. Over the period January 1–March 25, 2005, at the isentropic levels 450–500 K, about 60% of ozone was destroyed. During that winter, the zone of formation of polar stratospheric clouds went down to levels with very low values of potential temperature (down to 350 K), thus resulting in a noticeable destruction of ozone at low altitudes. By March 25, 2005, the chemical losses of total ozone attained 116 ± 10 DU (128 ± 10 DU at the cyclone boundary), which is a recordbreaking value of the Arctic.