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大气、陆地水和海洋之间的水质量迁移对海平面的影响一般假定为均匀薄层分布.但实际上,水质量负荷重新分布一方面会使地壳产生形变,另一方面会引起重力位势场变化(引力位和离心力位),这都会对海平面时空变化特征产生影响,两方面之和称为负荷自吸引效应(SAL).海洋模式模拟的时变洋底压力结果一般符合Boussinesq假设即体积守恒,忽略了大气、陆地水和海洋之间水质量交换的影响.本文基于海平面变化方程,联合陆地水模型、大气地表气压模型、海洋洋底压力模型和GRACE反演的冰川质量变化,详细讨论了2003-2010年SAL对海平面周年变化的影响.主要结论有:(1)SAL对全球海平面周年变化有显著影响,振幅在1.3~19 mm.其中近海岸和低纬度区域受影响较大.(2)在SAL引起的海平面周年振幅变化的因素中,陆地水储量变化因素最大,大气因素次之,非潮汐海洋影响最小.但非潮汐海洋对海平面周年相位空间变化的影响最为复杂.(3)通过与国际长期验潮站观测数据结果比较,在ECCO海洋模式估计的洋底压力结果中引入SAL,能多解释约5.3%观测信号方差. 相似文献
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联合卫星重力、卫星测高和海洋资料研究中国南海海平面变化 总被引：3，自引：0，他引：3
利用卫星测高、GRACE(Gravity Recovery and Climate Experiment)卫星重力和海洋实测与模式资料,在季节和年际尺度上,探讨了海水比容变化和海水质量变化对中国南海海平面变化的影响.在季节尺度上,利用测高和ECCO(Estimation of the Circulation and Climate of the Ocean)模式得到的南海海水质量引起的海平面变化的周年振幅和GRACE卫星独立观测的结果在地理分布上有很好的一致性.GRACE卫星观测到海水质量引起的南海平均海平面变化具有明显的季节性变化,其周年振幅为(2.7±0.4)cm;利用另一种独立的方法(测高减比容)得到的平均海平面周年振幅为(2.7±0.3)cm,两者符合得很好.在年际尺度上,南海平均海平面变化表现出明显的年际变化特征,且主要为比容海平面变化的贡献.卫星测高结果表明,1993～2009年的南海平均海平面变化为(5.5±0.7)mm/a,明显高于同期全球平均海平面变化趋势(3.3±0.4)mm/a.GRACE卫星观测到的海水质量变化没有表现出明显的趋势信号,这说明南海整体上与周边海域或陆地水的水循环是平衡的. 相似文献
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利用多通道奇异谱方法（MSSA）分析了1953~2003年亚洲和北美Palmer干旱指数（PDSI）与热带和北半球温带海洋海表面温度异常（SSTA）的主要周期振荡特征及其相互联系.结果表明：亚洲和北美PDSI以及SSTA均存在明显的3~6年的年际以及10年左右的年代尺度振荡;此外,亚洲PDSI还存在显著的6~8年的年际振荡.SSTA的年际振荡主要体现了ENSO的变化特征,而其年代尺度振荡的空间分布具有热带太平洋和北太平洋共同作用的类ENSO型.同时,MSSA的分析结果给出了亚洲和北美主要振荡信号的时间和空间演变特征.相关性分析表明,亚洲和北美PDSI的年际及年代尺度振荡均显示明显的对SSTA强迫信号的响应.对于年际振荡,亚洲PDSI对SSTA响应强于北美,但年代尺度振荡则反之.此外,亚洲和北美PDSI对于SSTA信号响应的关键区域也随时间尺度的不同而发生变化.亚洲的西西伯利亚、青藏高原东西两侧以及中西伯利亚东部在年际和年代尺度上均为受SSTA影响最显著的区域;在年际尺度上,北美中部地区的干湿变化与SSTA存在显著相关,而在年代尺度上,美国西部更易受SSTA年代尺度振荡的影响. 相似文献
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用经验正交函数分析方法,对中国近海14年多的测高海平面同化格网资料进行分析,给出了黄海、东海和南海各海平面变化主要主成分的空间变化和时间变化特征.用标准Morlet小波变换方法分析了各海区主成分时间变化序列的时频特征.分析结果表明,各主成分的空间分布特征与当地的海洋环流或洋流特征相对应.时频分析结果显示,中国近海海平面变化的显著周期主要为年周期信号.其次,黄海和东海还显示准2个月的非稳态信号,东海和南海具有较显著的半年周期信号,东海半年周期信号的能量不稳定.此外,在南海及台湾东部海域,首次发现存在较为显著的准540天周期信号,其动力学机制目前尚不明确.坎门和西沙验潮站资料的时频特征分析也验证了该信号的存在.最后本文给出了中国近海海平面在1993~2007年间的平均上升速率和其区域分布特征. 相似文献
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海平面变化是全球气候系统变化的一个组成部分,是环境变化的重要指标,也会影响沿海区域及岛屿的生态环境甚至存亡.全球海平面变化由海水质量变化和比容海平面变化构成.海水质量变化主要是由于两极冰盖和高山区的冰川融化流入海洋所致;比容海平面变化是由海水的温度和盐度变化所引起的,其中温度变化是最主要的因素.本文介绍了海平面变化各种监测技术的发展过程,并对海平面变化的研究现状进行了总结.所有研究成果均表明,近100多年以来,全球海平面一直处于上升态势;近几十年以来,海平面呈现加快上升并且越来越快的趋势.目前仍然存在一些问题:人们还没有完全掌握海平面变化规律,对未来海平面变化预测有较大不确定性;深海缺乏实测数据;厄尔尼诺—南方涛动(ENSO)的变化规律以及对海平面的影响;GRACE陆地与海洋信号无法完全分离以及GRACE与GRACE-FO之间的一致性分析等.这些问题都需要进一步开展研究. 相似文献
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本文利用卫星重力、卫星测高和海洋温盐数据反演计算全球海水质量变化,并分析其时空变化特征.卫星重力数据利用2003年1月~2006年12月的GRACE月时变重力场球谐系数,同时考虑替换一阶项和C20项,并进行了相关误差滤波、高斯滤波和陆地水文信号泄漏改正,计算得到海洋等效水高变化;利用相同时间跨度的卫星测高数据和海洋温度、盐度水文观测数据,计算全球海平面变化和比容海平面变化,反演得到海水质量变化.反演的两种海水质量变化的年际变化特征一致性较好.三种数据得到的长期趋势变化,与1993~2003年的结果相比,可以看出,海水质量变化加速,并已成为全球海平面上升的主要因素. 相似文献
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《地球物理学进展》2016,(2)
全球平均海平面年际变化中最突出的信号是由厄尔尼诺-南方涛动(ENSO)引起的.本文利用卫星测高、GRACE卫星重力、Argo海洋温盐实测数据、冰川消融质量数据和MEI指数,研究了全球海平面长期变化和年际变化的成因以及ENSO现象对海平面年际变化的影响.本文发现冰川消融贡献了海水质量变化的长期变化部分,其中格陵兰和南极洲的冰盖消融起主导作用.2003-2014年间,几次较大的厄尔尼诺以及拉尼娜现象均引起了海平面年际变化的响应.由于2010年强烈的拉尼娜现象,导致全球海平面下降了8 mm左右,同时期质量引起的海平面变化下降了6 mm,而比容海平面下降了2 mm.同时间段内,总的海平面年际变化、海水质量年际变化部分和比容海平面年际变化部分均与ENSO存在较高的相关性,测高得到的海平面年际变化、GRACE得到的海水质量年际变化和Argo浮标得到的比容海平面年际变化与MEI的相关系数分别达到0.41、0.48和0.56(置信度95%).经过对Argo分层实测数据分析,发现ENSO现象能够影响赤道太平洋区域0~300 m的海深的海水温度. 相似文献
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The development of ocean waves under explosive cyclones (ECs) is investigated in the Northwestern Pacific Ocean using a hindcast wave simulation around Japan during the period 1994 through 2014. A composite analysis of the ocean wave fields under ECs is used to investigate how the spatial patterns of the spectral wave parameters develop over time. Using dual criteria of a drop in sea level pressure below 980 hPa at the center of a cyclone and a decrease of at least 12 hPa over a 12-h period, ECs are identified in atmospheric reanalysis data. Two areas under an EC were identified with narrow directional spectra: the cold side of a warm front and the right-hand side of an EC (relative to the propagating direction). Because ECs are associated with atmospheric fronts, ocean waves develop very differently under ECs than they do under tropical cyclones. Moreover, ECs evolve very rapidly such that the development of the ocean wave field lags behind the peak wind speed by hours. In a case study of an EC that occurred in January 2013, the wave spectrum indicates that a warm front played a critical role in generating distinct ocean wave systems in the warm and cold zones along the warm front. Both the warm and cold zones have narrow directional and frequency spectra. In contrast, the ocean wave field in the third quadrant (rear left area relative to the propagation direction) of the EC is composed of swell and wind sea systems propagating in different directions. 相似文献
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A global eddy-admitting ocean/sea-ice simulation driven over 1958–2004 by daily atmospheric forcing is used to evaluate spatial
patterns of sea level change between 1993 and 2001. In the present study, no data assimilation is performed. The model is
based on the Nucleus for European Models of the Ocean code at the 1/4° resolution, and the simulation was performed without
data assimilation by the DRAKKAR project. We show that this simulation correctly reproduces the observed regional sea level
trend patterns computed using satellite altimetry data over 1993–2001. Generally, we find that regional sea level change is
best simulated in the tropical band and northern oceans, whereas the Southern Ocean is poorly simulated. We examine the respective
contributions of steric and bottom pressure changes to the total regional sea level changes. For the steric component, we
analyze separately the contributions of temperature and salinity changes as well as upper and lower ocean contributions. Generally,
the model results show that most regional sea level changes arise from temperature changes in the upper 750 m of the ocean.
However, contributions of salinity changes and deep steric changes can be locally important. We also propose a map of ocean
bottom pressure changes. Finally, we assess the robustness of such a model by comparing this simulation with a second simulation
performed by MERCATOR-Ocean based on the same core model, but differing by its short length of integration (1992–2001) and
its surface forcing data set. The long simulation presents better performance over 1993–2001 than the short simulation, especially
in the Southern Ocean where a long adjustment time seems to be needed.
In memory of my little brother Jean-Eudes, whose thirst for science filled out the rich discussions we had about my investigations
and his job as user-service provider for MERCATOR-Ocean. 相似文献
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Sea level variability along the US West Coast is analyzed using multi-year time series records from tide gauges and a high-resolution regional ocean model, the base of the West Coast Ocean Forecast System (WCOFS). One of the metrics utilized is the frequency of occurrences when model prediction is within 0.15 m from the observed sea level, F. A target level of F?=?90% is set by an operational agency. A combination of the tidal sea level from a shallow water inverse model, inverted barometer (IB) term computed using surface air pressure from a mesoscale atmospheric model, and low-pass filtered sea level from WCOFS representing the effect of coastal ocean dynamics (DYN) provides the most straightforward approach to reaching levels F>80%. The IB and DYN components each add between 5 and 15% to F. Given the importance of the DYN term bringing F closer to the operational requirement and its role as an indicator of the coastal ocean processes on scales from days to interannual, additional verification of the WCOFS subtidal sea level is provided in terms of the model-data correlation, standard deviation of the band-pass filtered (2–60 days) time series, the annual cycle amplitude, and alongshore sea level coherence in the range of 5–120-day periods. Model-data correlation in sea level increases from south to north along the US coast. The rms amplitude of model sea level variability in the 2–60-day band and its annual amplitude are weaker than observed north of 42 N, in the Pacific Northwest (PNW) coast region. The alongshore coherence amplitude and phase patterns are similar in the model and observations. Availability of the multi-year model solution allows computation and analysis of spatial maps of the coherence amplitude. For a reference location in the Southern California Bight, relatively short-period sea level motions (near 10 days) are incoherent with those north of the Santa Barbara Channel (in part, due to coastal trapped wave scattering and/or dissipation). At a range of periods around 60 days, the coastal sea level in Southern California is coherent with the sea surface height (SSH) variability over the shelf break in Oregon, Washington, and British Columbia, more than with the coastal SSH at the same latitudes. 相似文献
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人类活动引起全球变暖,衡量全球气候变化的指标有陆地、大气和海洋温度,水汽含量等等.研究对流层底层大气温度和水汽含量变化的传统方法是用数值天气预报模型和微波声纳,尚未实现用全球均匀覆盖的数据来做精确的定量研究.和GNSS系列卫星计划比较,最近发射的COSMIC卫星气象探测数据的空间、时间以及垂直分辨率都大大提高.采用COSMIC数据可以改进和量化南极洲的大气压力模型,并综合GNSS系列卫星测量的水汽和温度剖面研究全球气候变化.用一维协方差算法估计南极洲及附近海洋的大气压、温度和湿度剖面.把COSMIC卫星密集测量期间演算得到的大气折射率和GNSS系列卫星的结果进行比较.再和独立测量数据进行比较,包括南极洲自动气象观测站资料,数值天气预报模型资料,多种测高卫星水汽资料和海洋表面温度资料以及区域GPS水汽图.上述工作将改进发展中的气象遥感技术并应用于天气预报和空间天气预报及全球气候变化研究. 相似文献
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Ziming Ke Alexander E. Yankovsky 《Continental Shelf Research》2011,31(9):929-938
A set of numerical experiments has been performed in order to analyze the long-wave response of the coastal ocean to a translating mesoscale atmospheric cyclone approaching the coastline at a normal angle. An idealized two-slope shelf topography is chosen. The model is forced by a radially symmetric atmospheric pressure perturbation with a corresponding gradient wind field. The cyclone's translation speed, radius, and the continental shelf width are considered as parameters whose impact on the long wave period, modal structure, and amplitude is studied. Subinertial continental shelf waves (CSW) dominate the response under typical forcing conditions and on the narrower shelves. They propagate in the downstream (in the sense of Kelvin wave propagation) direction. Superinertial edge wave modes have higher free surface amplitudes and faster phase speeds than the CSW modes. While potentially more dangerous, edge waves are not as common as subinertial shelf waves because their generation requires a wide, gently sloping shelf and a storm system translating at a relatively high (∼10 m s−1 or faster) speed. A relatively smaller size of an atmospheric cyclone also favors edge wave generation. Edge waves with the highest amplitude (up to 60% of the forced storm surge) propagate upstream. They are produced by a storm system with an Eulerian time scale equal to the period of a zero-mode edge wave with the wavelength of the storm spatial scale. Large amplitude edge waves were generated during Hurricane Wilma's landfall (2005) on the West Florida shelf with particularly severe flooding occurring upstream of the landfall site. 相似文献
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我国地震海浪初步分析 总被引：1，自引：0，他引：1
总结了我国地震海浪的25次记录,在做初步分析后认为我国的地震海浪多由近海海洋地震引起,其多发地区为渤海沿岸与东南沿海一带.随着对沿海地区开发的深入,这类记载逐渐增多,受灾程度加大.另外分析了在社会历史变迁中,国家对海洋的开发政策、沿海开发下城市近海地理位置、沿海港口及海洋贸易的规模与地震海浪受灾程度之间的关系. 相似文献
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本文利用资料分析和数值模拟方法研究了欧亚地区夏季大气环流的相关性及其与亚洲夏季风的关联信号,以期为欧亚地区的气候变异及可预测性研究提供科学依据.结果表明:欧亚区域同期(JJA)500 hPa高度场年际变化的关键区包括热带区、中纬度的贝加尔湖和巴尔喀什湖之间以及欧洲地中海附近地区;表面气温的关键区主要位于热带海洋;海平面气压的关键区包括热带的海洋性大陆区域、印度洋和非洲大陆赤道附近部分区域、中高纬的贝加尔湖与巴尔喀什湖之间的地区.另外,夏季大气环流年际变化的春季关键区明显西移/南退,特别是表面气温(其西太平洋区不再是关键区).公用气候系统模式CCSM4.0的大气模式在给定海温年际变化的情况下对于上述大气环流相关场及其关键区的模拟基本合理,其中500 hPa高度场的模拟结果较好,海平面气压场的结果逊之;对于同期和前期的结果,模式都有夸大西太平洋海温影响的倾向.对于东亚夏季风指数与大气环流的同期年际变化信号而言,其空间分布基本表现为以30°N为界呈西南东北向的波列状分布;其春季前期信号中,30°N以南的显著区几乎都位于海洋,30°N以北主要位于欧洲、巴尔喀什湖与贝加尔湖之间的地区.南亚夏季风指数的前期显著相关区比同期明显西移/南退.总之,模式的模拟结果和观测结果相当吻合,但其同期模拟结果比前期的更好一些.这些结果说明:模式对于大气环流年际变化的耦合变化信息的刻画是基本合理的,这为利用气候模式进行有关可预测性研究和降尺度预测研究奠定了基础. 相似文献
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Paula Camus Fernando J. Méndez Inigo J. Losada Melisa Menéndez Antonio Espejo Jorge Pérez Ana Rueda Yanira Guanche 《Ocean Dynamics》2014,64(7):1025-1038
In this study, a method to obtain local wave predictor indices that take into account the wave generation process is described and applied to several locations. The method is based on a statistical model that relates significant wave height with an atmospheric predictor, defined by sea level pressure fields. The predictor is composed of a local and a regional part, representing the sea and the swell wave components, respectively. The spatial domain of the predictor is determined using the Evaluation of Source and Travel-time of wave Energy reaching a Local Area (ESTELA) method. The regional component of the predictor includes the recent historical atmospheric conditions responsible for the swell wave component at the target point. The regional predictor component has a historical temporal coverage (n-days) different to the local predictor component (daily coverage). Principal component analysis is applied to the daily predictor in order to detect the dominant variability patterns and their temporal coefficients. Multivariate regression model, fitted at daily scale for different n-days of the regional predictor, determines the optimum historical coverage. The monthly wave predictor indices are selected applying a regression model using the monthly values of the principal components of the daily predictor, with the optimum temporal coverage for the regional predictor. The daily predictor can be used in wave climate projections, while the monthly predictor can help to understand wave climate variability or long-term coastal morphodynamic anomalies. 相似文献
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A numerical model (two horizontal dimensions, vertically integrated) is used to investigate the generation of long ocean waves, ranging from 20 min to almost 2 h, at Buenos Aires continental shelf. The domain includes the Río de la Plata estuary and the continental shelf together and extends from 33.5° to 40.5°S latitude, and from 51° to 63°W longitude. Sea-level oscillations are modeled by forcing with passage of atmospheric cold fronts and atmospheric gravity waves. Both forcing mechanisms, which have been present during high activity lapses of long ocean waves, are mathematically implemented. After several numerical simulations, it is concluded that the pressure and wind fields associated to cold fronts do not generate long ocean waves in the area, though they do produce disturbances with periods longer than the tidal ones. On the other hand, it is so concluded that atmospheric gravity waves are an effective mechanism to force long ocean waves. Results obtained show that generation of long ocean waves is highly sensitive depending on the propagation direction and the phase speed of the atmospheric gravity waves. The long ocean wave event detected during the large-amplitude gravity-wave event of 13 October 1985 is successfully simulated. Finally, all our results suggest that atmospheric gravity waves are a highly effective mechanism forcing for the generation of long ocean waves in Buenos Aires coastal waters. 相似文献