热带印度洋偶极子发生和演变机制的数值研究   总被引：5，自引：0，他引：5  

李东辉  张铭  张瑰  谭言科 《海洋科学进展》2005,23(2):135-143

对中国科学院大气物理研究所(IAP)大气科学和地球流体力学数值模拟国家重点实验室(LASG)发展的第三代海洋模式(L30T63 OGCM)进行了改进。分析了该模式1959年1月—1998年12月的40a积分结果，以此研究热带印度洋偶极子发生、发展和消亡的物理机制。对数值模拟结果的分析表明，赤道印度洋表面异常东风引起的异常环流结构是偶极子发生、发展的主要动力学原因，其表面异常东风转换为异常西风所引起的异常环流结构调整是偶极子消亡的主要动力学原因；海气界面热通量异常的交换对热带印度洋海表温度距平偶极子模态的形成和演变起着重要的作用；垂直输送作用是热带印度洋次表层海温偶极子模态发生和演变的主要物理机制。  相似文献   

Recovery of thermohaline circulation under CO₂ stabilization and overshoot scenarios   总被引：1，自引：0，他引：1  

Norikazu. Nakashiki  Dong-Hoon Kim  Frank O. Bryan  Yoshikatsu Yoshida  Daisuke Tsumune  Koki Maruyama  Hideyuki Kitabata 《Ocean Modelling》2006,15(3-4):200

In this study we examine the behavior of the thermohaline circulation, as simulated by the Community Climate System Model version 3 (CCSM3), for several centuries following CO₂ stabilization for the SRES B1 and A1B scenarios and for an “overshoot” scenario in which CO₂ levels temporarily reach the same level as in the A1B scenario before declining to an ultimate stabilization level that is identical to the B1 case. While we find no evidence for irreversible changes of the thermohaline circulation in the overshoot experiment, the interplay of the different timescales of the temperature response of the surface and interior ocean does lead to a number of differences in the long-term response of the ocean between it and the B1 stabilization scenario where the same GHG levels are approached by different paths. The stronger initial warming and its slow penetration into the deeper ocean, followed by a transient surface cooling in the overshoot scenario leads to lower static stability, deeper mixing, and a more rapid recovery of the thermohaline circulation than in the B1 stabilization scenario. While the overshoot scenario recovers surface conditions (e.g. SST, sea ice extent) very similar to the B1 scenario shortly after reaching the same GHG levels, the additional accumulation of heat in the interior ocean during the period of higher forcing causes the global mean ocean temperature and steric sea level to remain higher than in the B1 stabilization scenario for at least another several centuries.  相似文献   

Wind-induced eddy motion in the lower St. Lawrence Estuary     

G. Mertz  V.G. Koutitonsky  Y. Gratton  M.I. El-Sabh 《Estuarine, Coastal and Shelf Science》1992,34(6)

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A Zonal Pathway for NADW in the South Atlantic     

Nelson?G.?HoggEmail author  Andreas?M.?Thurnherr 《Journal of Oceanography》2005,61(3):493-507

Several large deployments of neutrally buoyant floats took place within the Antarctic Intermediate (AAIW), North Atlantic Deep Water (NADW), and the Antarctic Bottom Water (AABW) of the South Atlantic in the 1990s and a number of hydrographic sections were occupied as well. Here we use the spatially and temporally averaged velocities measured by these floats, combined with the hydrographic section data and various estimates of regional current transports from moored current meter arrays, to determine the circulation of the three major subthermocline water masses in a zonal strip across the South Atlantic between the latitudes of 19°S and 30°S. We concentrate on this region because the historical literature suggests that it is where the Deep Western Boundary Current containing NADW bifurcates. In support of this notion, we find that a net of about 5 Sv. of the 15–20 Sv that crosses 19°S does continue zonally eastward at least as far as the Mid-Atlantic Ridge. Once across the ridge it takes a circuit to the north along the ridge flanks before returning to the south in the eastern half of the Angola Basin. The data suggest that the NADW then continues on into the Indian Ocean. This scheme is discussed in the context of distributions of dissolved oxygen, silicate and salinity. In spite of the many float-years of data that were collected in the region a surprising result is that their impact on the computed solutions is quite modest. Although the focus is on the NADW we also discuss the circulation for the AAIW and AABW layers.  相似文献   

Anomalous change of the Antarctic sea ice and global sea level change   总被引：3，自引：0，他引：3  

Xie Simei  Zou Bing  Wang Yi  Bao Chenglan 《海洋学报(英文版)》1996,15(2):193-208

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21世纪的大洋钻探——IODP   总被引：1，自引：0，他引：1  

薛发玉  翟世奎 《海洋地质与第四纪地质》2002,22(1):109-114

人类在地球科学方面已取得了相当大的成就,但就研究范围而言,却仅仅触及了地球的表层。IODP是一项国际性的大洋钻探计划,预期将于2003年10月正式开始实施。IODP将运用新的科学方法、科技设备,使人类对大洋底乃至整个地球系统得出更深、更广的认识。简单介绍了IODP的由来、组织机构、钻井技术、前期科学目标及中国的深海研究现状,提出中国参与IODP的必要性和可行性。通过了解21世纪的IODP在研究课题及研究技术方面的最新动态,不仅有助于我国根据国际动态调整深海研究的方向,制定符合我国需求的研究计划,而且有助于我国把握参与21世纪IODP的时机和策略,迎接“海洋世纪”的挑战,从而逐步实现“从地学大国走向地学强国”的目标。  相似文献   

Circulation and Brackish Water Dispersal in a Coastal Lagoon of Southwest Taiwan     

Sen Jan  Shenn-Yu Chao  Jia-Jang Hung 《Journal of Oceanography》2001,57(6):647-661

Modest observations and numerical experiments were conducted to investigate circulation and brackish water dispersal in a coastal lagoon southwest of Taiwan. The Chi-Ku Lagoon, partially shielded from the sea by a string of sandbar barriers with two entrances among them, receives modest and episodic runoff from Chi-Ku Stream. Flood and ebb tidal streams entering and leaving the two entrances are found to converge and diverge in a flow stagnation area inside the lagoon. Under weak wind conditions, brackish water is preferentially retained in the flow stagnation area. Besides the observations, scenario runs using a three-dimensional numerical model also indicate strong modulation by monsoon winds. Both summer southwest monsoon and winter northeast monsoon reduce brackish water retention; the latter is found to be more effective. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Numerical study of the summer temperature decrease induced by the enhancement of estuarine circulation in Fukuoka Bay     

Kazuhiro Aoki  Atsuhiko Isobe 《Journal of Oceanography》2006,62(2):207-217

The Princeton Ocean Model with realistic bottom topography has been used to investigate the summer temperature decrease in the past 25 years in Fukuoka Bay. The vertical mixing of the model is expressed by a scheme that effectively includes the influences of interannual variations of tidal currents and wind. The results show that the historical temperature decrease in summer has been caused by tidal currents and wind weakening in the past 25 years in Fukuoka Bay. The weakening of tidal currents and wind gives rise to weakening of the vertical mixing, and to enhancement of the estuarine circulation in the bay. The enhancement of the estuarine circulation activates the inflow of open-ocean water toward Fukuoka Bay. Coastal water in summer has therefore tended to be colder and more saline in the past 25 years. This interannual variation in coastal waters is called “open-oceanization” in this study. On the basis of the numerical model, it is anticipated that the temperature will decrease by 0.2°C in the next 25 years in Fukuoka Bay if the tide and wind weaken persistently as in the present bay.  相似文献   

Application of a two-dimensional depth-averaged hydrodynamic tidal model     

S. Sankaranarayanan  D. French McCay 《Ocean Engineering》2003,30(14):1807-1832

A two-dimensional hydrodynamic model application to the San Francisco Bay was performed using the Boundary-Fitted HYDROdynamic model (BFHYDRO). The model forcing functions consist of tidal elevations along the open boundary and fresh water flows from the Delta Outflow. The model-predicted surface elevations compare well with the observed surface elevations at five stations in San Francisco Bay. Mean error in the model predicted surface elevations and currents are less than 7 and 9%, respectively. Correlation coefficients for surface elevations and currents are higher than 0.94 and 0.95, respectively. The amplitudes and phases of the principal tidal constituents at 24 tidal stations in San Francisco Bay, obtained from a harmonic analysis of a 90-day simulation compare well with the observed data. The predicted amplitude and phase of the M₂ tidal constituent at these stations are respectively within 8 cm and 8° of the observed data. Maximum errors in the K₁ harmonic amplitudes and phases are less than 3 cm and 7° respectively. The asymmetric diurnal and semi-diurnal tidal ranges and spring and neap tidal cycles of the surface elevations and currents are well reproduced in the model at all stations.  相似文献   

Sensitivity of a global ocean model to increased run-off from Greenland   总被引：2，自引：0，他引：2  

Rüdiger Gerdes  William Hurlin  Stephen M. Griffies 《Ocean Modelling》2006,12(3-4):416-435

We study the reaction of a global ocean–sea ice model to an increase of fresh water input into the northern North Atlantic under different surface boundary conditions, ranging from simple restoring of surface salinity to the use of an energy balance model (EBM) for the atmosphere. The anomalous fresh water flux is distributed around Greenland, reflecting increased melting of the Greenland ice sheet and increasing fresh water export from the Arctic Ocean. Depending on the type of surface boundary condition, the large circulation reacts with a slow-down of overturning and gyre circulations. Restoring of the total or mean surface salinity prevents a large scale redistribution of the salinity field that is apparent under mixed boundary conditions and with the EBM. The control run under mixed boundary conditions exhibits large and unrealistic oscillations of the meridional overturning. Although the reaction to the fresh water flux anomaly is similar to the response with the EBM, mixed boundary conditions must thus be considered unreliable. With the EBM, the waters in the deep western boundary current initially become saltier and a new fresh water mass forms in the north-eastern North Atlantic in response to the fresh water flux anomaly around Greenland. After an accumulation period of several decades duration, this new North East Atlantic Intermediate Water spreads towards the western boundary and opens a new southward pathway at intermediate depths along the western boundary for the fresh waters of high northern latitudes.  相似文献