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1.
Feely RA Sabine CL Hernandez-Ayon JM Ianson D Hales B 《Science (New York, N.Y.)》2008,320(5882):1490-1492
The absorption of atmospheric carbon dioxide (CO2) into the ocean lowers the pH of the waters. This so-called ocean acidification could have important consequences for marine ecosystems. To better understand the extent of this ocean acidification in coastal waters, we conducted hydrographic surveys along the continental shelf of western North America from central Canada to northern Mexico. We observed seawater that is undersaturated with respect to aragonite upwelling onto large portions of the continental shelf, reaching depths of approximately 40 to 120 meters along most transect lines and all the way to the surface on one transect off northern California. Although seasonal upwelling of the undersaturated waters onto the shelf is a natural phenomenon in this region, the ocean uptake of anthropogenic CO2 has increased the areal extent of the affected area. 相似文献
2.
McGillicuddy et al. (Reports, 18 May 2007, p. 1021) proposed that eddy/wind interactions enhance the vertical nutrient flux in mode-water eddies, thus feeding large mid-ocean plankton blooms. We argue that the supply of nutrients to ocean eddies is most likely affected by submesoscale processes that act along the periphery of eddies and can induce vertical velocities several times larger than those due to eddy/wind interactions. 相似文献
3.
Barrows et al. (Reports, 5 October 2007, p. 86) presented cosmogenic exposure dates and data from an ocean sediment core that challenge evidence for glacier advance in New Zealand during the Younger Dryas event. We use modeling of geomorphic processes to argue that their cosmogenic exposure dates are inconclusive. 相似文献
4.
Based on the boron isotopic composition of coral from the southwestern Pacific, Pelejero et al. (Reports, 30 September 2005, p. 2204) suggested that natural variations in pH can modulate the impact of ocean acidification on coral reef ecosystems. We show that this claim cannot be reconciled with other marine carbon chemistry constraints and highlight problems with the authors' interpretation of the paleontologic data. 相似文献
5.
Unlike Le Quéré et al. (Reports, 22 June 2007, p. 1735), we do not find a saturating Southern Ocean carbon sink due to recent climate change. In our ocean model, observed wind forcing causes reduced carbon uptake, but heat and freshwater flux forcing cause increased uptake. Our inversions of atmospheric carbon dioxide show that the Southern Ocean sink trend is dependent on network choice. 相似文献
6.
Anthropogenic warming of Earth's climate system 总被引：3，自引：0，他引：3
Levitus S Antonov JI Wang J Delworth TL Dixon KW Broccoli AJ 《Science (New York, N.Y.)》2001,292(5515):267-270
We compared the temporal variability of the heat content of the world ocean, of the global atmosphere, and of components of Earth's cryosphere during the latter half of the 20th century. Each component has increased its heat content (the atmosphere and the ocean) or exhibited melting (the cryosphere). The estimated increase of observed global ocean heat content (over the depth range from 0 to 3000 meters) between the 1950s and 1990s is at least one order of magnitude larger than the increase in heat content of any other component. Simulation results using an atmosphere-ocean general circulation model that includes estimates of the radiative effects of observed temporal variations in greenhouse gases, sulfate aerosols, solar irradiance, and volcanic aerosols over the past century agree with our observation-based estimate of the increase in ocean heat content. The results we present suggest that the observed increase in ocean heat content may largely be due to the increase of anthropogenic gases in Earth's atmosphere. 相似文献
7.
Three-dimensional numerical ocean circulation model experiments that were designed to evaluate the circulation characteristics for the mid-Cretaceous ( approximately 100 million years ago) show that the primary direction of flow through the Tethys Ocean was eastward; in contrast, a westward flowing circumglobal Tethys current has been a consistent feature of earlier reconstructions of Cretaceous ocean circulation. The model studies demonstrate that (i) ocean circulation is sufficiently sensitive to the role of continental positions, sea level, and climate to limit the application of modern analogs to past circulations, and (ii) reconstructions based on limited biogeographic data may not provide unique surface circulation patterns. 相似文献
8.
Diadromous migration, in which some fish species migrate from freshwater and feed in the ocean (anadromous species) and others migrate from the ocean and feed in freshwater (catadromous), has long been perplexing. However, when the distribution of diadromous species is examined with respect to global patterns in aquatic productivity, this apparent paradox is resolved. The contrasting directions of migration can largely be explained by the relative availability of food resources in ocean and freshwater habitats. Oceans are more productive than freshwaters in temperate latitudes, and anadromous species predominate. In contrast, catadromous species generally occur in tropical latitudes where freshwater productivity exceeds that of the ocean. 相似文献
9.
有效浪高(Significant Wave Heights,SWH)是描述海浪的重要属性,SWH预测对于保障近岸工程设计以及海上作业安全具有重要意义。近年来,深度学习方法被用来对SWH预测,但是目前存在的方法无法有效捕捉SWH的长时间相关性,同时忽略了海洋多要素之间的局部关联。为此,本文提出了一种结合海洋多要素局部和全局特征的SWH预测模型(Multi-elements Local and Global Correlation for Wave height Prediction, MLG-SWH)。首先,以有效浪高、风速、周期等多要素作为输入,设计了局部-全局编码(Local-Global Embedding,LGE)模块提取海洋多要素的局部关联以及时间信息;然后,采用编-解码器作为基础网络结构提取多要素海浪序列特征,在编-解码器中设计了因果空洞卷积自注意力模块有效捕捉海洋多要素序列的全局长时间相关性,并在解码器中利用生成推理方式避免单步迭代预测产生的误差累积;最后,选取北大西洋海浪浪高变化特点不同的两个站点数据进行实验。相较于经典时间序列预测模型以及主流深度学习方法,所提MLG-SWH模型在24、48小时预测的均方误差(MSE)以及平均绝对误差(MAE)均为得最低,并在长时序预测方面具有较大的优势。 相似文献
10.
The carbon isotopic composition ((13)C/(12)C, expressed as δ(13)C) of fossil foraminifera is the primary tracer used to infer changes in past ocean ventilation, and its variations are interpreted by using the modern oceanic δ(13)C distribution as a framework. However, the present ocean δ(13)C distribution is strongly overprinted by isotopically light anthropogenic carbon dioxide. A correction for this oceanic C-13 Suess effect in the North Atlantic (NA) shows that the pristine NA δ(13)C distribution has a richer and more detailed structure that is more clearly related to water mass distributions. Our results revise some fundamental perceptions regarding glacial-interglacial ocean δ(13)C differences and allow paleo-δ(13)C variations to be understood within the context of modern climate variability. 相似文献
11.
The response of the ocean redox state to the rise of atmospheric oxygen about 2.3 billion years ago (Ga) is a matter of controversy. Here we provide iron isotope evidence that the change in the ocean iron cycle occurred at the same time as the change in the atmospheric redox state. Variable and negative iron isotope values in pyrites older than about 2.3 Ga suggest that an iron-rich global ocean was strongly affected by the deposition of iron oxides. Between 2.3 and 1.8 Ga, positive iron isotope values of pyrite likely reflect an increase in the precipitation of iron sulfides relative to iron oxides in a redox stratified ocean. 相似文献
12.
Atmospheric blocking and Atlantic multidecadal ocean variability 总被引：1，自引：0，他引：1
Atmospheric blocking over the northern North Atlantic, which involves isolation of large regions of air from the westerly circulation for 5 days or more, influences fundamentally the ocean circulation and upper ocean properties by affecting wind patterns. Winters with clusters of more frequent blocking between Greenland and western Europe correspond to a warmer, more saline subpolar ocean. The correspondence between blocked westerly winds and warm ocean holds in recent decadal episodes (especially 1996 to 2010). It also describes much longer time scale Atlantic multidecadal ocean variability (AMV), including the extreme pre-greenhouse-gas northern warming of the 1930s to 1960s. The space-time structure of the wind forcing associated with a blocked regime leads to weaker ocean gyres and weaker heat exchange, both of which contribute to the warm phase of AMV. 相似文献
13.
Impact of Antarctic Circumpolar Current development on late Paleogene ocean structure 总被引：1，自引：0，他引：1
Katz ME Cramer BS Toggweiler JR Esmay G Liu C Miller KG Rosenthal Y Wade BS Wright JD 《Science (New York, N.Y.)》2011,332(6033):1076-1079
Global cooling and the development of continental-scale Antarctic glaciation occurred in the late middle Eocene to early Oligocene (~38 to 28 million years ago), accompanied by deep-ocean reorganization attributed to gradual Antarctic Circumpolar Current (ACC) development. Our benthic foraminiferal stable isotope comparisons show that a large δ(13)C offset developed between mid-depth (~600 meters) and deep (>1000 meters) western North Atlantic waters in the early Oligocene, indicating the development of intermediate-depth δ(13)C and O(2) minima closely linked in the modern ocean to northward incursion of Antarctic Intermediate Water. At the same time, the ocean's coldest waters became restricted to south of the ACC, probably forming a bottom-ocean layer, as in the modern ocean. We show that the modern four-layer ocean structure (surface, intermediate, deep, and bottom waters) developed during the early Oligocene as a consequence of the ACC. 相似文献
14.
福建省休闲渔业暨“水乡渔村”品牌建设浅析 总被引：1，自引：0，他引：1
21世纪以来,中国休闲渔业发展迅速、效益良好、潜力巨大,是我国旅游业发展的一种新态势,传统渔业发展出现新契机。福建位于海峡西岸经济区,是我国东南海洋大省,更是渔业大省,发展休闲渔业条件十分优越。休闲渔业样板"水乡渔村"将与"森林人家"、"农家乐"共同打造海西农业休闲旅游的三大品牌。从福建省休闲渔业现状出发,对水乡渔村品牌发展进行分析,提出保障措施。 相似文献
15.
The ocean is an electrically conducting fluid that generates secondary magnetic fields as it flows through Earth's main magnetic field. Extracting ocean flow signals from remote observations has become possible with the current generation of satellites measuring Earth's magnetic field. Here, we consider the magnetic fields generated by the ocean lunar semidiurnal (M2) tide and demonstrate that magnetic fields of oceanic origin can be clearly identified in satellite observations. 相似文献
16.
It is proposed that Saturn's satellite Titan is covered by an ocean one to several kilometers deep consisting mainly of ethane. If the ocean is in thermodynamic equilibrium with an atmosphere of 3 percent (mole fraction) methane, then its composition is roughly 70 percent ethane, 25 percent methane, and 5 percent nitrogen. Photochemical models predict that ethane is the dominant end product of methane photolysis so that the evolving ocean is both the source and sink for continuing photolysis. The coexisting atmosphere is compatible with Voyager data. 相似文献
17.
The figures in Table 1 yield some interesting results. The total annual value of food and mineral resources taken from the ocean is $8.3 billion, in contrast to $309 billion from the land. Using the land value as the yardstick, if the annual value of produce from the ocean were in ratio to the area relationship of ocean and land, the ocean potential would be $750 billion; the actual recovery for 1964 was only 1.1 percent of that potential. This very low percentage is the basis for either great optimism for the future development of the ocean (on the basis of unrealized potential), or great pessimism (on the basis of high costs compared with further development of land resources, or present exploitation to near the limit of productivity). 相似文献
18.
Ammonium ion concentration in the primitive ocean 总被引：5，自引：0，他引：5
If ion exchange on clay minerals regulated the cationts in the primitive ocean as it does in the present ocean, the pH would have been 8 and the K(+) concentration 0.01M. Since NH(4)(+) and K(+) are similar in their claymineral equilibria, the maximum NH(4) (+) concentration in the primitive ocean would also have been 0.01M. An estimate of the minimum NH(4)(+) concentratin is 1 x 10(-3)M, based on the reversible deamination of aspartic acid and the assumption that aspartic acid is necessary for the origin of life. The rate of this nonenzymic deamnination is rapid on the geological time scale. 相似文献
19.
The vertical flux of nitrate across the thermocline in the upper ocean imposes a rigorous constraint on the rate of export of organic carbon from the surface layer of the sea. This export is the primary means by which the oceans can serve as a sink for atmospheric carbon dioxide. For the oligotrophic open ocean regions, which make up more than 75% of the world's ocean, the rate of export is currently uncertain by an order of magnitude. For most of the year, the vertical flux of nitrate is that due to vertical turbulent transport of deep water rich in nitrate into the relatively impoverished surface layer. Direct measurements of rates of turbulent kinetic energy dissipation, coupled with highly resolved vertical profiles of nitrate and density in the oligotrophic eastern Atlantic showed that the rate of transport, averaged over 2 weeks, was 0.14 (0.002 to 0.89, 95% confidence interval) millimole of nitrate per square meter per day and was statistically no different from the integrated rate of nitrate uptake as measured by incorporation of (15)N-labeled nitrate. The stoichiometrically equivalent loss of carbon from the upper ocean, which is the relevant quantity for the carbon dioxide and climate question, is then fixed at 0.90 (0.01 to 5.70) millimole of carbon per square meter per day. These rates are much lower than recent estimates based on in situ changes in oxygen over annual scales; they are consistent with a biologically unproductive oligotrophic ocean. 相似文献
20.
McNeil BI Matear RJ Key RM Bullister JL Sarmiento JL 《Science (New York, N.Y.)》2003,299(5604):235-239
We estimated the oceanic inventory of anthropogenic carbon dioxide (CO2) from 1980 to 1999 using a technique based on the global chlorofluorocarbon data set. Our analysis suggests that the ocean stored 14.8 petagrams of anthropogenic carbon from mid-1980 to mid-1989 and 17.9 petagrams of carbon from mid-1990 to mid-1999, indicating an oceanwide net uptake of 1.6 and 2.0 +/- 0.4 petagrams of carbon per year, respectively. Our results provide an upper limit on the solubility-driven anthropogenic CO2 flux into the ocean, and they suggest that most ocean general circulation models are overestimating oceanic anthropogenic CO2 uptake over the past two decades. 相似文献