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南大洋太平洋扇区中尺度涡旋的统计特性及其变化 总被引：1，自引：0，他引：1
中尺度涡旋在南大洋海洋动力学中具有重要地位,其对气候变化的响应表现也引起了海洋学家与气候学家的广泛关注。本文利用涡动动能与涡旋自动探测技术两种方法对南大洋太平洋扇区的涡旋特性及其变化进行了分析。与前人结果相一致的是,高值的涡动动能主要集中在南极极锋海区,并且自西向东逐渐减弱。在过去的20年里,涡动动能在太平洋扇区的显著增强也集中在中西部海域,这里也是南极绕极流斜压性较强的海域。涡旋统计特性揭示了涡动动能的空间分布及其年际变化主要归因于涡旋振幅与旋转速度,而并非涡旋个数或者涡旋半径。这些结果进一步确认了对应于南半球环状模正位相的绕极西风异常改变了南大洋的涡旋特性,从而表现出涡旋活跃性增强。 相似文献
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A strong spring Wyrtki jet(WJ) presents in May 2013 in the eastern equatorial Indian Ocean. The entire buildup and retreat processes of the spring WJ were well captured by two adjacent Acoustic Doppler Current Profilers mounted on the mooring systems. The observed zonal jet behaved as one intraseasonal event with the significant features of abrupt emergence as well as slow disappearance. Further research illustrate that the pronounced surface westerly wind burst during late-April to mid-May, associated with the active phase of a robust eastwardpropagating Madden–Julian oscillation in the tropical Indian Ocean, was the dominant reason for the rapid acceleration of surface WJ. In contrasting, the governing mechanism for the jet termination was equatorial wave dynamics rather than wind forcing. The decomposition analysis of equatorial waves and the corresponding changes in the ocean thermocline demonstrated that strong WJ was produced rapidly by the wind-generated oceanic downwelling equatorial Kelvin wave and was terminated subsequently by the westward-propagating equatorial Rossby wave reflecting from eastern boundaries of the Indian Ocean. 相似文献
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北太平洋经向翻转环流(NPMOC)是北太平洋所有经向翻转环流圈的总称,拥有5个环流圈结构.其中,热带环流圈(TC)、副热带环流圈(STC)和深层热带环流圈(DTC)位于北太平洋热带-副热带海域,是该海域间经向物质和能量交换的重要通道.主要运用NEMO模式对这3个经向翻转环流圈的年际变化特征和机理进行了研究.结果表明,TC、STC和DTC的经向流量都具有显著的年际变化特征:在El Nio期间,TC的南、北向流量均减弱,STC的北向流量增强、南向流量减弱,DTC的南向流量减弱;而在La Nia期间则相反.敏感性试验表明,在风应力强迫下得到的TC、STC南、北向流量和DTC南向流量的年际变化特征都很显著,并与在风应力、热通量和淡水通量共同强迫下得到的结果非常一致;而仅在热通量和淡水通量的强迫下,各分支流量的年际变化均较小.由此可见,风场驱动是引起北太平洋经向翻转环流年际变化的主要驱动因素,而热通量和淡水通量的影响却较小. 相似文献
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北太平洋经向翻转环流是北太平洋所有经向翻转环流圈的总称,目前它拥有五个环流圈,即副热带环流圈(the subtropical cell,STC)、热带环流圈(the tropical cell,TC)、副极地环流圈(the subpolar cell,SPC)、深层热带环流圈(the deep tropical cell,DTC)和温跃层环流圈(the thermohaline cell,THC)。这些环流圈是北太平洋经向物质和能量交换的重要通道,它们的变化对海洋上层热盐结构和气候变化皆有重要影响。迄今,人们已对STC、TC和DTC的结构形态、变化特征与机理开展了广泛而深入的研究,并对STC的极向热输送特征也做了一些初步分析。但应指出的是,关于SPC和THC的研究仍较少,迄今尚不清楚这两个环流圈的三维结构和变异机理;而且,对北太平洋经向翻转环流的热盐输送研究尚处于起步阶段,目前对各环流圈的热盐输送特征、变化规律和变异机理仍知之甚少,这些科学问题亟待深入研究。 相似文献
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Based on the Simple Ocean Data Assimilation(SODA) products,we study the mean properties and variations of the Southern Hemisphere subpolar gyres(SHSGs) in this paper.The results show that the gyre strengths in the SODA estimates are(55.9±9.8)×10~6m~3/s for the Weddell Gyre(WG),(37.0±6.4) ×10~6m~3/s for the Ross Gyre(RG),and(27.5±8.2)×10~6m~3/s for the Australian-Antarctic Gyre(AG),respectively.There exists distinct connectivity between the adjacent gyres and then forms an oceanic super gyre structure in the southern subpolar oceans.And the interior exchanges are about(8.0±3.2)×10~6m~3/s at around 70°E and(4.3±3.1)×10~6m~3/s at around 140°E.The most pronounced variation for all three SHSGs occurs on the seasonal time scale,with generally stronger(weaker)SHSGs during austral winter(summer).And the seasonal changes of the gyre structures show that the eastern boundary of the WG and AG extends considerably further east during winter and the interior exchange in the super gyre structure increases accordingly.The WG and RG also show significant semi-annual changes.The correlation analyses confirm that the variations of the gyre strengths are strongly correlated with the changes in the local wind forcing on the semi-annual and seasonal time scales. 相似文献
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热带太平洋是影响全球气候系统的重要区域,热带太平洋海表温度(SST)的长期变化趋势模拟是国际研究领域关注的热点。基于12个参加第六期国际耦合模式比较计划(CMIP6)的模式结果,本研究对1950年至1999年间多模式模拟得到的热带太平洋SST增暖现象进行了初步评估。结果表明,不同模式对热带太平洋SST增暖的模拟能力差别较大,特别在赤道东太平洋区域,部分模式模拟得到了偏强的SST降温趋势,与实际观测中的SST增温趋势相反,多模式集合平均结果给出了中部型厄尔尼诺事件的增温趋势。通过引入SST增暖变率分析方法,本研究对多模式模拟的热带太平洋SST在过去50 a中的增暖内在变化进行了进一步评估,结果表明目前各模式对热带太平洋SST增暖变率模拟偏弱,空间分布差异较大。 相似文献
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We analyzed the temporal and spatial variation, and interannual variability of the North Pacific meridional overturning circulation using an empirical orthogonal function method, and calculated mass transport using Simple Ocean Data Assimilation Data from 1958–2008. The meridional streamfunction field in the North Pacific tilts N-S; the Tropical Cell (TC), Subtropical Cell (STC), and Deep Tropical Cell (DTC) may be in phase on an annual time scale; the TC and the STC are out of phase on an interannual time scale, but the interannual variability of the DTC is complex. The TC and STC interannual variability is associated with ENSO (El Niño-Southern Oscillation). The TC northward, southward, upward, and downward transports all weaken in El Niños and strengthen in La Niñas. The STC northward and southward transports are out of phase, while the STC northward and downward transports are in phase. Sea-surface water that reaches the middle latitude and is subducted may not completely return to the tropics. The zonal wind anomalies over the central North Pacific, which control Ekman transport, and the east-west slope of the sea level may be major factors causing the TC northward and southward transport interannual variability and the STC northward and southward transports on the interannual time scale. The DTC northward and southward transports decrease during strong El Niños and increase during strong La Niñas. DTC upward and downward transports are not strongly correlated with the Niño-3 index and may not be completely controlled by ENSO. 相似文献
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北太平洋经向翻转环流(NPMOC)是北太平洋所有经向翻转环流圈的总称。其中,热带环流圈(TC)、副热带环流圈(STC)和深层热带环流圈(DTC)位于北太平洋热带-副热带海域,是该海域经向物质和能量交换的重要通道。基于NEMO模式分别对TC、STC和DTC经向流量的季节变化特征和机理进行了模拟研究,驱动场增强和减弱情况下的敏感性试验表明,风应力是TC和STC南、北向输送以及DTC南向输送季节变化的主要影响因素,而热通量和淡水通量的影响较小;风应力和热盐通量季节变化情况下的敏感性试验表明,TC和STC的南、北向输送以及DTC的南向输送主要是由风应力的季节振荡引起的,而热通量和淡水通量的影响较小。 相似文献
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