How are large western hemisphere warm pools formed?

During the boreal summer the Western Hemisphere warm pool (WHWP) stretches from the eastern North Pacific to the tropical North Atlantic and is a key feature of the climate of the Americas and Africa. In the summers following nine El Niño events during 1950–2000, there have been five instances of extraordinarily large warm pools averaging about twice the climatological annual size. These large warm pools have induced a strengthened divergent circulation aloft and have been associated with rainfall anomalies throughout the western hemisphere tropics and subtropics and with more frequent hurricanes. However, following four other El Niño events large warm pools did not develop, such that the mere existence of El Niño during the boreal winter does not provide the basis for predicting an anomalously large warm pool the following summer.In this paper, we find consistency with the hypothesis that large warm pools result from an anomalous divergent circulation forced by sea surface temperature (SST) anomalies in the Pacific, the so-called atmospheric bridge. We also find significant explanations for why large warm pools do not always develop. If the El Niño event ends early in the eastern Pacific, the Pacific warm anomaly lacks the persistence needed to force the atmospheric bridge and the Atlantic portion of the warm pool remains normal. If SST anomalies in the eastern Pacific do not last much beyond February of the following year, then the eastern North Pacific portion of the warm pool remains normal. The overall strength of the Pacific El Niño does not appear to be a critical factor. We also find that when conditions favor a developing atmospheric bridge and the winter atmosphere over the North Atlantic conforms to a negative North Atlantic Oscillation (NAO) pattern (as in 1957–58 and 1968–69), the forcing is reinforced and the warm pool is stronger. On the other hand, if a positive NAO pattern develops the warm pool may remain normal even if other circumstances favor the atmospheric bridge, as in 1991–92. Finally, we could find little evidence that interactions internal to the tropical Atlantic are likely to mitigate for or against the formation of the largest warm pools, although they may affect smaller warm pool fluctuations or the warm pool persistence.     

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.     

气体吸收对“HY-1A”CCD数据处理的影响分析模拟与瑞利散射的吸收修正

卫星传感器接收到的辐射能量不仅受到大气中分子和气溶胶散射的影响,还受到气体分子吸收的影响.对于可见光和近红外波段的水色遥感,吸收气体主要是臭氧、水汽和氧气,因此若传感器的光谱范围包含了这些气体的吸收波段,则应该在数据处理——计算瑞利、气溶胶反射率和透过率时予以考虑.波段光谱宽度为20 nm(两个近红外波段为40nm)的SeaWiFS在数据处理时主要考虑了臭氧和水汽的影响,并在计算气溶胶反射率时对受氧气吸收影响的波段进行了单独修正[1].由于“HY-1A”CCD的四个波段的光谱宽度均超过100 nm,覆盖了三种主要吸收气体的部分吸收线,因此它受到的气体影响会更大.     

Analysis of seabed instability using element free Galerkin method

Wave-induced seabed instability, either momentary liquefaction or shear failure, is an important topic in ocean and coastal engineering. Many factors, such as seabed properties and wave parameters, affect the seabed instability. A non-dimensional parameter is proposed in this paper to evaluate the occurrence of momentary liquefaction. This parameter includes the properties of the soil and the wave. The determination of the wave-induced liquefaction depth is also suggested based on this non-dimensional parameter. As an example, a two-dimensional seabed with finite thickness is numerically treated with the EFGM meshless method developed early for wave-induced seabed responses. Parametric study is carried out to investigate the effect of wavelength, compressibility of pore fluid, permeability and stiffness of porous media, and variable stiffness with depth on the seabed response with three criteria for liquefaction. It is found that this non-dimensional parameter is a good index for identifying the momentary liquefaction qualitatively, and the criterion of liquefaction with seepage force can be used to predict the deepest liquefaction depth.     

Study of the seawater transparency field in the Crimea-Caucasus shelf area

This paper discussesin situ observational data on the directed light attenuation index in the near-surface layer, collected in September 1987. The absolute light attenuation index has been evaluated for a near-shore strip of water 10–15 miles in width. When multidisciplinary research is conducted in the open sea, this part of the sea surface remains unstudied, as the observational grid for it is made larger than the spatial-temporal parameters of the biophysical processes producing optical inhomogeneities.Translated by Vladimir A. Puchkin.     

虾池的溶解氧含量及其补充量和消耗量

对对虾养殖池塘溶解氧含量及其收支情况的研究结果表明，虾池DO值具有明显的季节和昼夜变化。浮游植物光合作用是虾池溶解氧补充的主要来源，夏季最高可超过5mg／（dm3·d）。养殖后期对虾的耗氧量占总耗氧量的34％，底质和池水耗氧量分别占30％和35％。根据虾池氧的收支情况讨论了池养对虾的生产容量。     

南沙群岛海区晚第四纪碳酸盐沉积

本文研究了五个柱状沉积物的碳酸盐沉积。根据沉积物的陆源碎屑和生物骨屑ＣａＣＯ３沉积作用的特点，把本区沉积物分为五种沉积类；碳酸盐生物组成的门类较多，以有孔虫为主，其次为珊瑚，腹足类等；碳酸盐矿物以低镁方解石为主，还有高镁方解石和文石；与沉积物中ＣａＣＯ３有关的化学元素１０多种。这些元素和稀土元素的含量，比值等，是区分礁相，礁体过渡带和非礁相的标志。所有这些碳酸盐沉积作用的特点表明，区内存在着五种沉     

湄洲湾泥沙活动及海底冲淤变化

湄洲湾沙源少,海水含沙量低,平均值10～20g/m~3。冬季受东北季风及浙闽沿岸流影响,湾口含沙量高,达到34g/m~3;夏季受径流影响,湾内含沙量相对偏高,达到16g/m~3。泥沙的运移趋势:主航道基本朝外,两侧朝里。受强潮流作用,深槽及水下潮流冲沟受到冲刷,斜坡及潮坪略有淤积。     

Evidence for the evolution of an oxygen minimum layer at the beginning of S-1 sapropel deposition in the eastern Mediterranean

The sediments of the eastern Mediterranean basin contain a series of organic-rich sapropels intercalated with organic-poor nannofossil oozes. Until recently the timing of the onset of sapropel formation was not known accurately because of the low resolution achievable by conventional radiocarbon dating. Compilation of all available ¹⁴C-AMS dates show that the base of S-1 (the most recent sapropel) was initiated 8800 years B.P. (¹⁴C age corrected by 400 years for reservoir effect) under a 500 m water column and moved progressively into deeper water reaching depths of 3500 m at 8200 years B.P. The linear correlation between the age of S-1 onset and water depth

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suggests that formation of sapropels moved into deeper water at a rate of 1000 m/200 year. A model is suggested in which export production which sank below the well-mixed surface layers (500 m) was respired consuming dissolved oxygen in the Levantine deep water until a threshold value was reached when sapropels began to be preserved in the sediment. This resulted in a progressively deepening oxygen minimum zone with time until eventually the entire deep water in the basin was oxygen depleted. Assuming that the threshold value for sapropel formation was complete anoxia, it was calculated that primary productivity in the basin during the deposition of S-1 was a factor of 5 greater than that found at present.