海洋对热带气旋响应的研究 Ⅱ.不同海洋热力结构下的情形

利用中二层非线性原始方程海洋模式，研究海洋在自身不同热力结构下对热带气旋的响应。计算结果表明，初始混合层（ML）深度和层结强度对海表温（SST）和ML深度变化起着十分重要的作用。初始ML深度对海流量值影响较大，层结强度则较小。东海陆架区特殊的海洋热力结构，极易造成SST下降。海洋对7002号台风响应的模拟结果与观测资料较一致。     

Geographical distribution of general aerobic heterotrophic bacteria in surficial sediments from the Chukchi Sea and Canadian Basin

This paper determined the abundance of General Aerobic heterotrophic Bacteria(GAB) in surficial sediments from the Chukchi Sea and the Canadian basin by using MPN and discussed their geographical distribution.The result shows that the determination percentages of the GAB were high,even till 100 percentage.The abundance range and averages of GAB for 4℃and 25℃ were from 4.00×102 to 2.40×106,1.71×106 ind.·g-1(wet sample) and from 2.40×105 to 2.40×107,1.10×107 ind.·g-1(wet sample) respectively.Not only the abundance range but also the averages of GAB in 25℃ were higher than that in 4℃.The abundance of GAB in sediments show a tendency that it is roughly greater in the lower latitudinal area than in the higher latitudinal area.The abundance of GAB increased from east to west as for the longitudinal distribution.With the water depth increasing,the abundance of GAB at 4℃ decreased,but GBA at 25℃ is not changed obviously with water depth.It seems that warmer circumstantial temperature is more suitable for some GAB.     

Basin‐scale stream‐flow forecasting using the information of large‐scale atmospheric circulation phenomena

It is well recognized that the time series of hydrologic variables, such as rainfall and streamflow are significantly influenced by various large‐scale atmospheric circulation patterns. The influence of El Niño‐southern oscillation (ENSO) on hydrologic variables, through hydroclimatic teleconnection, is recognized throughout the world. Indian summer monsoon rainfall (ISMR) has been proved to be significantly influenced by ENSO. Recently, it was established that the relationship between ISMR and ENSO is modulated by the influence of atmospheric circulation patterns over the Indian Ocean region. The influences of Indian Ocean dipole (IOD) mode and equatorial Indian Ocean oscillation (EQUINOO) on ISMR have been established in recent research. Thus, for the Indian subcontinent, hydrologic time series are significantly influenced by ENSO along with EQUINOO. Though the influence of these large‐scale atmospheric circulations on large‐scale rainfall patterns was investigated, their influence on basin‐scale stream‐flow is yet to be investigated. In this paper, information of ENSO from the tropical Pacific Ocean and EQUINOO from the tropical Indian Ocean is used in terms of their corresponding indices for stream‐flow forecasting of the Mahanadi River in the state of Orissa, India. To model the complex non‐linear relationship between basin‐scale stream‐flow and such large‐scale atmospheric circulation information, artificial neural network (ANN) methodology has been opted for the present study. Efficient optimization of ANN architecture is obtained by using an evolutionary optimizer based on a genetic algorithm. This study proves that use of such large‐scale atmospheric circulation information potentially improves the performance of monthly basin‐scale stream‐flow prediction which, in turn, helps in better management of water resources. Copyright © 2007 John Wiley & Sons, Ltd.     

Late Quaternary stratigraphy of the northern Rockall trough and Faeroe-Shetland channel,northeast Atlantic Ocean

A late Quaternary deep-water stratigraphic framework has been established for the deep-water areas (>450m) of the northern Rockall Trough and Faeroe-Shetland Channel. Four stratigraphic units (1–4) are identified; these are primarily biostratigraphic units based on dinoflagellate cyst evidence. Unit 1 represents the late Weichselian glacial (pre-13 000 yr BP); unit 2 the Late Glacial Interstadial (11 000-13 000 yr BP); unit 3 is of Younger Dryas age (10 000-11 000 yr BP); and unit 4 represents the Holocene interglacial (post-10 000 yr BP). This stratigraphy is supported by the discovery of the mixed Vedde Ash (10 600 yr BP) and North Atlantic Ash zone 1, and the Saksunarvatn Ash (9000–9100 yr BP), concentrated in units 3 and 4 respectively. The sedimentology indicates that the oceanographic regime underwent a major change between the glacial and interglacial stages. This is marked by the onset of strong bottom current activity, allied to the restoration of overflow of the Norwegian Sea Deep Water into the North Atlantic, towards the end of the Younger Dryas Stadial. Despite intense bioturbation and bottom-current reworking the basic stratigraphic framework is maintained. Recognition of two volcanic ash markers enables correlation with established onshore and offshore sequences of marine and non-marine environments.     

Mechanics of tidally driven fractures in Europa's ice shell

A fracture mechanics model is developed for the initiation and propagation of a crack through a porous ice layer of finite thickness under gravitational overburden. It is found that surface cracks generated in response to a tidally induced stress field may penetrate through the entire outer brittle layer if a subsurface ocean is present on Europa. Such penetration is found to be very unlikely in the absence of an ocean. A cycloidal crack would then form as a sequence of near instantaneous discrete failures, each extending roughly the brittle layer thickness in range, linked with a much lower apparent propagation speed set by the moving tidal stress field. The implications of this porous ice fracture model for ice-penetrating radar scattering loss and seismic activity are quantified.     

北冰洋78°N冰站近地层参数的观测研究

利用2003年8月22日-9月3日中国北极科学考察队在北冰洋78°N浮冰站获得的近地层观测资料,采用整体输送法对北冰洋浮冰近地层特征参数进行了分析研究。结果表明,在考察期间,雪面吸收的净辐射仅为3.6 W/m2,其中以感热和潜热向大气输送的能量分别占52%和31%,向海冰深层传导的热量很少;近中性层结条件下的平均拖曳系数Cdn为1.16×10-3,略小于75°N北冰洋浮冰上近中性层结的Cdn。与1999年75°N附近冰站观测结果的对比表明,当海冰密度及冰站所在浮冰的尺度不同时,海冰与大气相互作用的热力学和动力学过程的差异显著,在研究北冰洋地区海/冰/气相互作用对气候过程影响时,应考虑这一问题。     

热带东太平洋中国多金属结核开辟区深海成矿环境的氨基酸表征

为了解中国多金属结核开辟区沉积物有机质活性及深海成矿沉积环境特征，使用高效液相色谱（HPLC）法分析了表层沉积物氨基酸的组成状况。结果显示该区表层沉积物中氨基酸与氨基糖含量(干样)均较低，分别在0.30～0.59 mg·g-1及 0.10～0.17 mg·g-1之间。其中以中性氨基酸占绝对优势，占50%以上，其次为酸性氨基酸和含氢氧基氨基酸，分别占17%和11%，碱性氨基酸占9%，芳香与含硫氨基酸均在5%以下,表明深海沉积环境为氧化环境，且偏碱性条件。表征有机质活性的Asp/β Ala、Glu/γ Aba及DI值（（Glu+Phe+Leu+Ala+Val）/ (β Ala+γ Aba)）分别为1.1～1.9，0.8～2.2和1.4～2.9，表明该区有机质成熟度已很高。蛋白氨基酸/非蛋白氨基酸的比值为1.0～2.0，葡萄糖胺/半乳糖胺比值则在1.7～3.0之间变化，表明该海区有机质经过强烈的细菌改造，即海区存在强烈的细菌活动，活性较低，表征了多金属结核有机—微生物成矿的可能性。     

A Petrogenetic Model of Basalts from the Northern Central Indian Ridge:3-11°S

1 Introduction The Northern Central Indian Ridge (NCIR) between 3° and 11°S latitudes is joined to the north with the slow spreading Carlsberg Ridge (CR; ~24–26 mm/a, full spreading rate) and to the south with the intermediate spreading Southern Central Indian Ridge (SCIR; ~50 mm/ a) (Fig. 1). Earlier petrological investigations of the Central Indian Ridge were concentrated either on or along the CR to the north and at the southern end of the CIR up to the Rodriguez Triple Junc…     

Modification of the loop current warm core eddy by Hurricane Gilbert (1988)

Numerical investigation of Hurricane Gilbert (1988) effect on the Loop Current warm core eddy (WCE) in the Gulf of Mexico is performed using the Modular Ocean Model version 2 (MOM2). Results show that the storm-induced maximum sea surface temperature (SST) decrease in Gilbert’s wake is over 2.5°C, as compared with the 3.5°C cooling in the absence of the WCE. The near-inertial oscillation in the wake reduces significantly in an along-track direction with the presence of the WCE. This effect is also reflected between the mixed layer and the thermocline, where the current directions are reversed with the upper layer. After two inertial periods (IP), the current reversal is much less obvious. In addition, it is demonstrated that Hurricane Gilbert wind stress increases the current speed of the WCE by approximate 133%. With the forcing of Gilbert, the simulated translation direction and speed of the WCE towards the Mexican coast are closer to the observed (42% more accurate in distance and 78% more accurate in direction) compared with the simulation without the Gilbert forcing. The simulated ocean response to Gilbert generally agrees with the recent observations in Hurricane Fabian.