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本文概括了近几十年来，关于德里克海峡附近绕极流研究的进展，这些研究主要以实际观测资料为基础，说明了德里克海峡附近海洋锋面分布和绕极流的体积输运，其中，主要的海洋锋面有：亚南极锋，极锋和陆缘水边界；而德里克海峡绕极流的体积输运则代表了太平洋和大西洋两大洋之间通过德里克海峡的水量交换，读者可通过本文加深关于德里克海峡锋面成因和绕极流机制的理解。 相似文献
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基于垂向混合坐标系统的海洋模式HYCOM建立了全球大洋气候态环流场.在此基础上与前人研究工作进行对比,分析和讨论了全球风生大洋环流场的季节变化情况.从模拟结果看该模式具有较好的模拟能力,可以合理地模拟南极绕极流、赤道流系、黑潮和湾流等世界各主要大洋流系.从断面温度场、流函数分布和断面流量场等分析显示:南极绕极流堪称世界最强流,湾流整体强于黑潮,3者都具有夏季增强、冬季减弱的特点.HYCOM模式在国外的研究方兴未艾,而在国内的应用尚处在起步阶段.本文通过对该模式的介绍和结果分析,向读者推荐使用该模式. 相似文献
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中国南大洋水团、环流和海冰研究进展(1995-2002) 总被引：2，自引：0，他引：2
总结了1995年以来中国在南大洋物理海洋学研究和南极海冰研究中所取得的成果。普里兹湾海区是中国南大洋研究的重点区域，研究表明，在该海区存在显著的深层水涌升和陆架水北扩现象，某些年份深层水与陆架水混合后产生了较重的水体，但是尚未发现生成南极底层水的直接证据。在普里兹湾所处的印度洋区段，亚热带锋、亚南极锋和极锋表现出显著的时空变化，特别是不同年份的锋面位置存在较大的摆动。该海区的南极绕极流既是风生的，也受到密度场的影响。在凯尔盖朗海台的地形引导作用下，南极绕极流表现出显著的非纬向性特征。南极海冰除了显著的季节变化以外，也表现出长期变化的趋势。此变化与海洋、大气中的其它变化有一定的相关性，表现为两极海冰涛动、南方海洋涛动等多种变化模态，对我国气候也有一定的影响。 相似文献
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南印度洋绕极深层水的性质和空间分布以及南极绕极流的作用 总被引：1，自引：0，他引：1
利用世界大洋环流实验的南大洋观测温度、盐度和溶解氧资料,分析并说明了南印度洋绕极深层水的性质和空间分布特征,比较了30°E,90°E和145°E断面上温度、盐度和溶解氧的垂直分布及其异同,着重指出,在南印度洋的这3个不同经度断面上,绕极深层水和锋面的不同特征与南极绕极流越洋输运和南印度洋绕极深层水的经向运动有着密切的关系。实际上,绕极流的越洋输运是南大西洋与南印度洋之间以及南印度洋与南太平洋之间水交换的主要动力因素,对形成绕极深层水的物理性质的空间分布有着重要的作用。 相似文献
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末次盛冰期(LGM)是古气候学研究的热门时期之一,很多学者采用不同的研究方法探讨了该时期气候环境变量的特征和变化,尽管各自的侧重点有所不同,某些结论也尚不一致,但是目前初步形成了关于LGM时期的很多共识。针对近20年来不同学者利用重构数据和数值模式模拟等方法对LGM时期开展的研究工作,从物理海洋研究的角度和需求,对LGM时期的地形分布、大气辐射和CO2浓度、海冰和陆地冰川分布、海表面温度以及海洋环流等主要物理要素进行系统描述,总结了LGM时期气候环境的基本特征。结果发现LGM时期海洋表层温度降低,但存在着区域性的温度升高,深海海洋各大洋温度更趋于一致性,冰川受季节性影响较大,主要差别在于北半球,大西洋经向翻转流和南极绕极流的强度仍存在争议。随着LGM时期气候变化研究的深入,关于该时期气候环境基本特征的认识也会继续得以深化和完善,关于过去20年间LGM时期气候要素研究的综述也会对后续数据重构和数值模拟工作具有一定的参考作用。 相似文献
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关键海区潜沉率对全球变暖停滞的可能影响 总被引：1，自引：0，他引：1
本文从潜沉率入手，探究了潜沉率在全球变暖停滞过程中可能发挥的作用。本文利用SODA资料首先分析了全球潜沉率的时空分布特征，然后基于EOF分解明确了北大西洋翻转流区域和南极绕极流区域是潜沉率变率较大的两个海区，在此基础上选出了4个关键海区研究了局地潜沉率变化与全球海表温度异常之间的相关关系，最后对关键区潜沉率变化的原因进行了初步探索。结果表明，北大西洋翻转流和南极绕极流范围内的关键区域与全球变暖停滞之间存在超前10年的相关关系，潜沉过程可能是北大西洋翻转流和南极绕极流对全球变暖停滞产生作用的一种机制。平流项在这些关键区域的潜沉率变化中起主导作用。在南极绕极流地区，海面风应力的大小与该区域的潜沉变化密切相关。 相似文献
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采用TOPEX/POSEIDON(T/P)卫星高度计 1 993年 1月— 2 0 0 0年 1 2月海面高度数据 ,研究包含了整个南极绕极流流系 (40°— 6 0°S)的海面高度低频变化。首先采用EOF分解方法获取南大洋时空分布的主要模态 ,前 3个EOF模态分别占总方差的 2 4 .8%、1 3 .8%和 1 0 .7%。然后采用EMD方法分别分析了各个EOF模态的时间系数曲线的组成成分 ,对南极绕极流海域的各种时间尺度变化给出了清晰的描述 ,对于不同尺度变化所占的比例得到了定量的结果。研究结果表明 ,EOF的各个模态不仅在形态上存在差异 ,而且具有相互独立的物理背景。EOF的第一模态主要体现了以太阳辐射冬夏差异形成的年周期变化 ,另一个显著的特征就是南极绕极流从 1 993— 2 0 0 0年海面的整体上升趋势。EOF的第二模态体现了陆地地形对南极绕极流的约束作用 ,同时也显示了ENSO过程对南极绕极流 ,特别是对南太平洋的海面高度变化的影响。EOF的第三模态则体现了南极绕极流对南大洋表面风场东西方向不均匀变化的响应。同时 ,本文的研究也证明了EOF与EMD方法联合使用对揭示大范围时空变化有重要的实际意义 相似文献
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The circulation of northwestern Bay of Bengal is modeled using a three-dimensional Princeton Ocean Model (POM). Orthogonal curvilinear grid is used to get a higher resolution along the coastal boundaries. Numerical simulations on climatological scale for premonsoon were compared with those with and without fresh water during monsoon season. The simulations for monsoon season without freshwater discharge at head Bay show intensification of the premonsoon features. The presence of lower SSTs and higher sea surface salinities as compared to premonsoon season along the coast substantiate this observation. The pole-ward moving East Indian Coastal Current (EICC) extends along-shore up to 20.5°N. Simulations with freshwater discharge for Monsoon season indicate that freshwater plume constitutes an equator-ward moving EICC branch opposing the pole-ward moving branch. The freshwater discharge modifies sea surface elevations along the northwestern coastal Bay of Bengal, in turn suppressing the coastal upwelling. Absence of freshwater plume imparts a significant change in the oceanic features in north western parts of Bay of Bengal. 相似文献
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Flow cytometry investigation of picoplankton across latitudes and along the circum Antarctic Ocean 总被引：2，自引：1，他引：1
Using a flow cytometer (FCM) onboard the R/V Xuelong during the 24th Chinese Antarctic cruise, picoplankton community structure and biomass in the surface water were examined along the latitude and around the Antarctic Ocean. Salinity and temperature were automatically recorded and total Chla was determined. Along the cruise, the abundance of Synechococcus, Prochlorococcus, pico-eukaryotes and heterotrophic bacteria ranged in 0.001-1.855×108 ind./L, 0.000-2.778￡108 ind./L, 0.002-1.060×108 ind./L and 0.132-27.073×108 ind./L, respectively. Major oceanic distribution of Synechococcus and Prochlorococcus appeared between latitudes 30°N and 30°S. Prochlorococcus was mainly influenced by water temperature, water mass combination and freshwater inflow. Meanwhile, Synechococcus distribution was significantly associated with landing freshwater inflow. Pico-eukaryotes and heterotrophic bacteria were distributed all over the oceans, but with a relatively low abundance in the high latitudes of the Antarctic Ocean. Principal Component Analysis showed that at same latitude of Atlantic Ocean and Indian Ocean, picoplankton distribution and constitution were totally different, geographical location and different water masses combination would be main reasons. 相似文献
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《Deep Sea Research Part I: Oceanographic Research Papers》2007,54(11):2005-2021
The prevailing view regarding the oceanic meridional overturning cell (MOC) in the Atlantic is that, for a given North Atlantic freshwater flux, it has at least two stable states, one with a large surface (northward) mass flux and the other with a small flux. It has been argued that some abrupt paleoclimatic changes which occurred in the North Atlantic and the regions surrounding it might be related to a shift between these two distinctly different states. Here, we argue that, although the Atlantic MOC can indeed collapse due to a large freshwater flux, the actual ocean does not have multiple states for the same freshwater flux.The two state scenarios has its origin in the analytical box model of Stommel [1961. Thermohaline convection with two stable regimes of flow. Tellus 2, 244–230] and in a series of numerical models starting with that of Bryan [1986. High latitude salinity effects and interhemispheric thermohaline circulations. Nature 303, 301–304]. Using hybrid global analytical models involving both wind and density variations we demonstrate here that the application of Stommel's model to the North Atlantic yields multiple solutions because it considers the origin of the MOC upper limb to be a box whose export of water depends on its temperature and salinity which are not known in advance. When this origination box is replaced by a (observationally supported) Southern Ocean box whose surface water export depends solely on the wind, and when, together with this choice, the diapycnal diffusivities and eddy viscosities are taken to be as small as the usually observed values, the multi-solution scenario disappears and one gets only a single solution.Using the Uvic climate model, we re-confirm earlier results and argue that numerical models have multiple stable states and a resulting hysteresis because of the spuriously high eddy diffusivity that is typically used explicitly or implicitly. This is so because the diffusivity artificially introduces dense-to-light water conversion analogous to Stommel's origination box. Since we used a level model rather than a layered or isopynic model, the small vertical diffusivity limit still retains significant cross-isopycnal mixing due to the horizontal diffusivity, which is not supported by observations. Consequently, while our runs shows a tendency to no-hysteresis in the limit of small cross-isopycnal flow, we cannot actually reach that limit. 相似文献
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本文利用Argo表层盐度、OSCAR海流等数据,基于盐度收支方程的平流输送项来阐述海洋平流输送对热带印度洋表层盐度的调整作用;利用淡水输运量计算公式揭示6条关键断面海洋平流输送对表层盐度空间结构的调整机制。结果表明,海洋平流将赤道西印度洋和阿拉伯海的高盐水输送到低盐海域的赤道东印度洋和孟加拉湾、安达曼海;将赤道东印度洋和孟加拉湾、安达曼海的低盐水输送到高盐海域的赤道西印度洋、阿拉伯海以及赤道南印度洋海域,起到了调整印度洋盐度基本平衡的作用。断面淡水输运量的分析结果表明,导致苏门答腊岛西部海域的强降水中心与低盐中心不重合,澳大利亚西部海域的强蒸发中心与高盐中心不重合的主要原因是水平环流所致;夏季,来自赤道西印度洋和阿拉伯海的高盐水在西南季风环流的驱动下,入侵孟加拉湾,是导致孟加拉湾夏季表层盐度较高的主要原因。 相似文献
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本文利用Argo盐度、SODA海流量、OAFlux蒸发量和TRMM降水量等数据,采用盐度收支方程定量给出了印度洋混合层盐度的收支,揭示了整个印度洋净淡水通量项、平流项、垂向卷夹项的分布、季节变化特征及其对混合层盐度变化的主要贡献。结果表明,就多年平均而言,平流项负贡献（15.14%）大于正贡献（9.89%）,说明平流输送把低盐水输送到高盐海域,导致印度洋高盐海域混合层的盐度降低。净淡水通量项的分布和季节变化与降水量基本一致,且正贡献（13.70%）大于负贡献（7.81%）,说明净淡水通量项使印度洋的混合层盐度升高（因为多年平均蒸发量大于降水量）。盐度季节变化显著海域的进一步分析表明,6?11月,西南季风漂流把赤道西印度洋的低盐水（相对阿拉伯海高盐水而言）输送到阿拉伯海西部海域,导致该海域的盐度降低。平流输送把孟加拉湾湾口和中部的高盐水带到北部海域,是导致北部海域盐度升高的主要原因。 相似文献
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The mean seasonal variability of turbulent heat fluxes in the tropical Atlantic Ocean is examined using the Woods Hole Oceanographic Institution(WHOI) flux product.The most turbulent heat fluxes occur during winter seasons in the two hemispheres,whose centers are located at 10°~20°N and 5°～15°S respectively.In climatological ITCZ,the turbulent heat fluxes are the greatest from June to August,and in equatorial cold tongue the turbulent heat fluxes are the greatest from March to May.Seasonal variability of sensible heat flux is smaller than that of latent heat flux and mainly is dominated by the variations of air-sea temperature difference.In the region with larger climatological mean wind speed(air-sea humidity difference),the variations of air-sea humidity difference(wind speed) dominate the variability of latent heat flux.The characteristics of turbulent heat flux yielded from theory analysis and WHOI dataset is consistent in physics which turns out that WHOI's flux data are pretty reliable in the tropical Atlantic Ocean. 相似文献
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The annual mean volume and heat transport sketches through the inter-basin passages and transoceanic sections have been constructed based on 1 400-year spin up results of the MOM4p1. The spin up starts from a state of rest, driven by the monthly climatological mean force from the NOAA World Ocean Atlas(1994). The volume transport sketch reveals the northward transport throughout the Pacific and southward transport at all latitudes in the Atlantic. The annual mean strength of the Pacific-Arctic-Atlantic through flow is 0.63×106 m3/s in the Bering Strait. The majority of the northward volume transport in the southern Pacific turns into the Indonesian through flow(ITF) and joins the Indian Ocean equatorial current, which subsequently flows out southward from the Mozambique Channel, with its majority superimposed on the Antarctic Circumpolar Current(ACC). This anti-cyclonic circulation around Australia has a strength of 11×106 m3/s according to the model-produced result. The atmospheric fresh water transport, known as P-E+R(precipitation minus evaporation plus runoff), constructs a complement to the horizontal volume transport of the ocean. The annual mean heat transport sketch exhibits a northward heat transport in the Atlantic and poleward heat transport in the global ocean. The surface heat flux acts as a complement to the horizontal heat transport of the ocean. The climatological volume transports describe the most important features through the inter-basin passages and in the associated basins, including: the positive P-E+R in the Arctic substantially strengthening the East Greenland Current in summer; semiannual variability of the volume transport in the Drake Passage and the southern Atlantic-Indian Ocean passage; and annual transport variability of the ITF intensifying in the boreal summer. The climatological heat transports show heat storage in July and heat deficit in January in the Arctic; heat storage in January and heat deficit in July in the Antarctic circumpolar current regime(ACCR); and intensified heat transport of the ITF in July. The volume transport of the ITF is synchronous with the volume transport through the southern Indo-Pacific sections, but the year-long southward heat transport of the ITF is out of phase with the heat transport through the equatorial Pacific, which is northward before May and southward after May. This clarifies the majority of the ITF originating from the southern Pacific Ocean. 相似文献
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基于2004—2013年的南海北部开放航次数据和1980—2010年Simple Ocean Data Assimilation（SODA）数据，发现南海北部次表层水体盐度在2004—2005年间盐度显著增大，相比于气候态均值分别增加了0.1和0.14，而且温盐特征曲线显示盐度增大的现象主要发生在150m以浅。2004年净淡水通量仅略低于气候态均值，2005年净淡水通量则明显高于气候态均值，因此净淡水通量不会是导致此高盐事件的有利因素。我们进一步通过块体简化盐度收支方程，定量评估盐度收支方程里中平流输运项（包括跨海盆经吕宋海峡的平流输运项和南海海盆内部南北海盆之间的平流输运项）的贡献。发现在2004年，通过吕宋海峡进入南海北部的盐含量输运显著大于气候态均值，是导致南海北部上层水体盐度迅速增大的主要原因。为探究2005年南海北部盐度持续增强的原因，我们进一步比较2004年和2005年的平流项演变，发现相对于2004年，虽然2005年吕宋海峡盐含量输运略低于气候态均值，但南海内部南海南北海盆间（通过18°N断面进入南海北部）的盐含量输运增强，即在2005年，海盆内部经向平流盐输运的贡献是促使南海北部上层盐度继续增强的关键因素。 相似文献
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利用耦合了平板海洋模型的全球气候模式进行了大量的格林函数实验,以探究两极地区对于施加在中低纬度海域的热强迫的气候响应。结果表明,北极地区的气候不仅受到距离较近的北太平洋与北大西洋的影响,远离北极的热带太平洋以及南太平洋也对其气候有显著的影响,南极地区的气候则主要是受到邻近的南大洋的影响。通过经验正交函数法的进一步分析发现,北极响应最显著的区域包括波弗特海(Beaufort Sea)、拉普捷夫海(Laptev Sea)以及北极中心区附近;南极地区的响应主要集中在别林斯高晋海(Bellinsgauzen Sea)区域。另外,利用温度归因法对辐射反馈过程和大气能量输运分解发现,北极地区表面温度的响应主要是受到了反照率反馈以及垂直递减率反馈的影响,而南极地区的响应则主要是反照率反馈发挥了作用。 相似文献
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Robert Dickson Bert Rudels Stephen Dye Michael Karcher Jens Meincke Igor Yashayaev 《Progress in Oceanography》2007,73(3-4):210
As the world warms, the expectation is that the freshwater outflows from the Arctic Ocean to the North Atlantic will strengthen and may act to suppress the rate of the climatically-important Atlantic meridional overturning circulation. Hitherto, however, we have lacked the system of measurements required to estimate the totality of the freshwater flux through subarctic seas. Though observations remain patchy and rudimentary in places, we piece-together the results from recent large-scale observational programmes together with associated modelling, to establish preliminary maps of the rates and pathways of freshwater flux through subarctic seas. These fluxes are calculated according to two reference salinities, S = 34.8 to conform with the majority of estimates reported in the literature, and S = 35.2, the salinity of the inflowing Atlantic water, to calculate the freshwater balance of the ‘Arctic Mediterranean’. We find that 148 mSv of freshwater enters the Nordic Seas across its northern boundary. There it is supplemented by around 54 mSv of freshwater from Baltic runoff, Norwegian runoff, P − E and Greenland ice melt, so that the total freshwater contribution to the Nordic Seas from all sources is 202 mSv. Of this, around 51 mSv of freshwater is estimated to pass south to the deep Atlantic in the dense water overflows leaving an assumed balance of 151 mSv to leave the Nordic Seas in the upper water export through Denmark Strait. The corresponding estimate for the freshwater outflow west of Greenland is 103 mSv relative to 35.2 so that the total freshwater flux reaching the North Atlantic through subarctic seas is around 300 mSv. 相似文献