前苏联七十年海冰研究回顾     

曲维政  李若钝 《海洋预报》1993,10(3):31-42

本文简要介绍了前苏联近七十年来海冰研究的主要成果及其采用的一些预报方法。  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   

热带西太平洋海-气热量交换特征分析     

吴迪生 《热带海洋学报》1993,(1)

本文采用1985年12月12日至1986年2月8日“向阳红14”号调查船在太平洋调查所获海洋水文气象资料,计算了四种热交换量。结果表明:海-气热输送与天气系统和海洋水文条件关系密切。冬季,在各种天气系统条件下西太平洋及中太平洋的大气主要是从海洋得到热量,其中以黑潮流经的海域最为明显,而热交换的方式主要是海洋以潜热的形式把热量输送给大气。  相似文献   

The Mid-atlantic Ridge (31°S–34°30′S): Temporal and spatial variations of accretionary processes     

P. J. Fox  N. R. Grindlay  K. C. MacDonald 《Marine Geophysical Researches》1991,13(1):1-20

The ridge located between 31° S and 34°30′S is spreading at a rate of 35 mm yr⁻¹, a transitional velocity between the very slow (≤20 mm yr⁻¹) opening rates of the North Atlantic and Southwest Indian Oceans, and the intermediate rates (60 mm yr⁻¹) of the northern limb of the East Pacific Rise, and the Galapagos and Juan de Fuca Ridges. A synthesis of multi-narrow beam, magnetics and gravity data document that in this area the ridge represents a dynamically evolving system. Here the ridge is partitioned into an ensemble of six distinct segments of variable lengths (12 to 100 km) by two transform faults (first-order discontinuities) and three small offset (< 30 km) discontinuities (second-order discontinuities) that behave non-rigidly creating complex and heterogeneous morphotectonic patterns that are not parallel to flow lines. The offset magnitudes of both the first and second-order discontinuities change in response to differential asymmetric spreading. In addition, along the fossil trace of second-order discontinuities, the lengths of abyssal hills located to either side of a discordant zone are observed to lengthen and shorten creating a saw-toothed pattern. Although the spreading rate remains the same along the length of the ridge studied, the morphology of the spreading segments varies from a deep median valley with characteristics analogous to the rift segments of the North Atlantic to a gently rifted axial bulge that is indistinguishable from the shape and relief of the intermediate rate spreading centers of the East Pacific Rise (i.e., 21°N). Like other carefully surveyed ridge segments at slow and fast rates of accretion, the along-axis profiles of each ridge segment are distinctly convex upwards, and exhibit along-strike changes in relief of 500m to 1500 between the shallowest portion of the segment (approximate center) and the segment ends. Such spatial variations create marked along-axis changes in the morphology and relief of each segment. A relatively low mantle Bouguer anomaly is known to be associated with the ridge segment characterized by a gently rifted axial bulge and is interpreted to indicate the presence of focused mantle upwelling (Kuo and Forsyth, 1988). Moreover, the terrain at the ends of each segment are known to be highly magnetized compared to the centers of each segment (Carbotte et al, 1990). Taken together, these data clearly establish that these profound spatial variations in ridge segment properties between adjoining segments, and along and across each segment, indicate that the upper mantle processes responsible for the formation of this contrasting architecture are not solely related to passive upwelling of the asthenosphere beneath the ridge axis. Rather, there must be differences in the thermal and mechanical structure of the crust and upper mantle between and along the ridge segments to explain these spatial variations in axial topography, crustal structure and magnetization. These results are consistent with the results of investigations from other parts of the ridge and suggest that the emplacement of magma is highly focused along segments and positioned beneath the depth minimum of a given segment. The profound differences between segments indicate that the processes governing the behavior of upwelling mantle are decoupled and the variations in the patterns of axis flanking morphology and rate of accretion indicate that processes controlling upwelling and melt production vary markedly in time as well. At this spreading rate and in this area, the accretionary processes are clearly three-dimensional. In addition, the morphology of a ridge segment is not governed so much by opening rate as by the thermal structure of the mantle which underlies the segment.  相似文献   

潮汐对瞬态气候响应模拟的影响研究     

于溢  刘海龙  林鹏飞  兰健 《海洋学报(英文版)》2020,39(1):52-62

In this study, the impact of oceanic processes on the sensitivity of transient climate change is investigated using two sets of coupled experiments with and without tidal forcing, which are termed Exp_Tide and Exp_Control,respectively. After introducing tidal forcing, the transient climate response(TCR) decreases from 2.32 K to 1.90 K,and the surface air temperature warming at high latitudes decreases by 29%. Large ocean heat uptake efficiency and heat storage can explain the low TCR in Exp_Tide. Approximately 21% more heat is stored in the ocean in Exp_Tide(1.10×10~(24) J) than in Exp_Control(0.91×10~(24) J). Most of the large ocean warming occurs in the upper 1 000 m between 60°S and 60°N, primarily in the Atlantic and Southern Oceans. This ocean warming is closely related to the Atlantic Meridional Overturning Circulation(AMOC). The initial transport at mid-and high latitudes and the decline in the AMOC observed in Exp_Tide are both larger than those observed in Exp_Control. The spatial structures of AMOC are also different with and without tidal forcing in present experiments. The AMOC in Exp_Tide has a large northward extension. We also investigated the relationship between AMOC and TCR suggested by previous studies using the present experiments.  相似文献   

Seasonal Variability of Near-Surface Heat Budget of Selected Oceanic Areas in the North Tropical Indian Ocean   总被引：1，自引：0，他引：1  

Chithra Shaji  Satoshi Iizuka  Tomonori Matsuura 《Journal of Oceanography》2003,59(1):87-103

The results obtained from an Ocean General Circulation Model (OGCM), the Modular Ocean Model 2.2, forced with the National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis data, and observational data have been utilized to document the climatological seasonal cycle of the upper ocean response in the Tropical Indian Ocean. We address the various roles played by the net surface heat flux and the local and remote ocean dynamics for the seasonal variation of near-surface heat budget in the Tropical Indian Ocean. The investigation is based in seven selected boxes in the Arabian Sea, Bay of Bengal and the Equatorial Indian Ocean. The changes of basin-wide heat budget of ocean process in the Arabian Sea and the Western Equatorial Indian Ocean show an annual cycle, whereas those in the Bay of Bengal and the Eastern Equatorial Indian Ocean show a semi-annual cycle. The time tendency of heat budget in the Arabian Sea depends on both the net surface heat flux and ocean dynamics while on the other hand, that in the Bay of Bengal depends mainly on the net surface flux. However, it has been found that the changes of heat budget are very different between western and eastern regional sea areas in the Arabian Sea and the Bay of Bengal, respectively. This difference depends on seasonal variations of the different local wind forcing and the different ocean dynamics associated with ocean eddies and Kelvin and Rossby waves in each regional sea areas. We also discuss the comparison and the connection for the seasonal variation of near-surface heat budget among their regional sea areas. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Spatial and temporal variability of microplankton and detritus, and their export to the shelf sediments in the upwelling area off Concepción, Chile (∼36°S), during 2002-2005     

Humberto E. González  Eduardo Menschel  Carola Aparicio 《Progress in Oceanography》2007,75(3):435-451

Seasonal variations in diversity and biomass of diatoms, tintinnids, and dinoflagellates and the contribution of microplankton and faecal material to the vertical flux of particulates were investigated at one time series station T (station 18) between 2002 and 2005 and at a grid of stations during November 2004 in the coastal and oceanic area off Concepción (36°S), Chile. The variations were analysed in relation to water column temperature, dissolved oxygen, nutrient concentration, offshore Ekman transport, and chlorophyll-a concentration. Abundance was estimated as cell numbers per litre and biomass in terms of biovolume and carbon units.A sharp decrease with depth was observed in the abundance of both phytoplankton and microzooplankton during the whole annual cycle; over 70% of their abundance was concentrated in the upper 10 m of the water column. Also, a clear seasonality in microplankton distribution was observed at station T, with maxima for diatoms, tintinnids, and dinoflagellates every summer (centred on January) from 2002 to 2005.On the grid of stations, the maximum integrated (0-50 m) micro-phytoplankton abundances (>1 × 10⁹ cells m⁻²) occurred at the coastal stations, an area directly influenced by upwelling. A similar spatial distribution was observed for the integrated (0-200 m) faecal carbon (with values up to 632 mg C m⁻²). Tintinnids were distributed in all the first 300 miles from the coast and dinoflagellates were more abundant in oceanic waters.At station T, the average POC export production (below 50 m depth) was 16.6% (SD = 17%; range 2-67%; n = 16). The biological-mediated fluxes of carbon between the upper productive layer and the sediments of the continental shelf off Concepción depend upon key groups of phytoplankton (Thalassiosira spp., Chaetoceros spp.) and zooplankton (euphausiids) through the export of either cells or faecal material, respectively.  相似文献   

Crustal Structures of the Northernmost South China Sea: Seismic Reflection and Gravity Modeling   总被引：2，自引：0，他引：2  

Yi-Ching Yeh  Shu-Kun Hsu 《Marine Geophysical Researches》2004,25(1-2):45-61

The South China Sea (SCS) is a marginal sea off shore Southeast Asia. Based on magnetic study, oceanic crust has been suggested in the northernmost SCS. However, the crustal structure of the northernmost SCS was poorly known. To elaborate the crustal structures in the northernmost SCS and off southwest Taiwan, we have analyzed 20 multi-channel seismic profiles of the region. We have also performed gravity modeling to understand the Moho depth variation. The volcanic basement deepens southeastwards while the Moho depth shoals southeastwards. Except for the continental margin, the northernmost SCS can be divided into three tectonic regions: the disturbed and undisturbed oceanic crust (8–12 km thick) in the southwest, a trapped oceanic crust (8 km thick) between the Luzon-Ryukyu Transform Plate Boundary (LRTPB) and Formosa Canyon, and the area to the north of the Formosa Canyon which has the thickest sediments. Instead of faulting, the sediments across the LRTPB have only displayed differential subsidence offset of about 0.5–1 s in the northeast side, indicating that the LRTPB is no longer active. The gravity modeling has shown a relatively thin crust beneath the LRTPB, demonstrating the sheared zone character along the LRTPB. However, probably because of post-spreading volcanism, only the transtension-shearing phenomenon of volcanic basement in the northwest and southeast ends of the LRTPB can be observed. These two basement-fractured sites coincide with low gravity anomalies. Intensive erosion has prevailed over the whole channel of the Formosa Canyon.  相似文献   

氯甲烷的海洋生物地球化学研究     

陆小兰  杨桂朋  高先池 《中国海洋大学学报(自然科学版)》2006,36(6):868-874

对氯甲烷的海洋生物地球化学循环的研究进展进行述评。介绍了氯甲烷在海洋环境中的来源、分布、去除、海-气通量、大气氯甲烷的源、汇估算及海水中氯甲烷的分析方法等方面,并提出在国内海域进行氯甲烷研究的几点设想。  相似文献   

珠江口水域微表层中的痕量金属     

陈金斯  李飞永  朱卓洪 《热带海洋学报》1994,(3)

采用自制滚筒式自动采样器采样，研究了珠江口水域微表层中Ｆｅ，Ｍｎ，Ｃｕ，Ｐｂ，Ｚｎ，Ｃｄ的含量、分布变化及富集状况。并通过颗粒痕量金属／颗粒Ｆｅ比值计算，探讨了痕量金属的来源。结果表明：Ｃｕ，Ｐｂ，Ｚｎ，Ｃｄ在微表层的平均富集系数分别为２．３，１．４，３．０和１．９。颗粒态Ｆｅ，Ｍｎ的平均富集系数为１．１和０．９。各种金属有明显的季节和空间变化，有各种不同的来源。  相似文献