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1.
南海季风型海-气耦合模态的时空特征及其与中国夏季降水的关系 总被引：2，自引：0，他引：2
使用NCEP/NCAR的海表温度(SST)、海面10 m风场的月平均再分析资料,用联合SVD(CSVD)的方法研究了不同季节南海的海气耦合模的时空分布特征及其与中国夏季降水的关系。通过对不同季节的海-气耦合模的年际变化特征的分析。结果发现:第一模态为最显著模态,模态协方差贡献比在四季均超过80%,空间上SST表现为与南海等深线相一致的海盆模态,风场上主要表现为弱的冬季风或弱的夏季风,各个季节的海-气耦合模态都主要反映了SST-蒸发-风反馈这样1种正反馈的海-气相互作用过程,而且冬季风期间这种相互作用要更强烈些。时间系数均主要表现为一致的上升趋势和1976年前后的年代际突变,以及与ENSO相关的年际变化特征。冬、夏季弱的季风对应暖SST的特征体现了这种耦合模态隔季相关的特征,都对应夏季华南旱(涝)、江南涝(旱),华北、山东半岛旱(涝),东北涝(旱)这样1种波列状的旱涝相间分布。 相似文献
2.
源区黑潮热输送低频变异及其与中国近海SST异常变化的关系 总被引：6，自引：0，他引：6
基于长时间序列的水温和盐度资料，通过动力计算方法估算了源区黑潮（18°N断面）热输送量，分析了源区黑潮热输送变异和中国近海SST异常的年际、年代际时空变化特征及两者之间的相互关系．结果显示，源区黑潮热输送异常呈现出显著的以2—7、10～20a和约30a为主周期的年际、年代际变化，且具有线性增强的长期变化趋势．并约于1976年前后发生了一次显著气候跃变．中国近海SST年际、年代际异常变化的最显著区域位于渤海、黄海、东海海域和台湾海峡．源区黑潮热输送变异在年际、年代际尺度上与中国近海SST异常变化密切相关，源区黑潮热输送变异可能是影响中国近海SST异常变化的重要因素之一． 相似文献
3.
南海表层水温场的时空特征与长期变化趋势 总被引：9，自引：0，他引：9
本文利用月平均表层水温（SST）、850hPa经向风和西太平洋副热带高压等资料分析了南海表层水温距平（SSTA）场的时空特征和长期变化趋势，并探讨了SST的年际和长期变化原因．结果表明，南海SSTA场分别存在着以全域同位相振荡和东南一西北向反位相振荡的两个主要模态．其中，前者是主要模态，以年际振荡为主，而后者则是次要模态，以季节振荡为主．进一步分析发现，南海中部的SST存在着显著的年际和年代际变化，并在1981年前后发生了一次由低到高的气候转变，而且南海中部SST的长期变化趋势非常明显，在1950—2006年间增温0．92℃．相关和合成分析表明，南海SST的年际和长期变化可能是由南海上空的经向风异常和西太平洋副热带高压的纬向变动引起的． 相似文献
4.
The adjustment of the North Pacific Subtropical and Subpolar Gyres towards changes in wind stress leads to different time-scale variabilities, which plays a significant role in climate changes. Based on the Simple Ocean Data Assimilation (SODA) and Global Ocean Data Assimilation System (GODAS) datasets, the variations of the Subtropical and Subpolar Gyres are diagnosed using "three-dimension Ocean Circulation Diagnostic Method", and established three types of index series describe the strength, meridional and depth center of the Subtropical and Subpolar Gyres. The above indices present the seasonal, interannual and interdecadal variabilities of the Subtropical and Subpolar Gyres, which proves well. Both the Gyres are the strongest in winter, but the Subtropical Gyre is the weakest in summer and the Subpolar Gyre is the weakest in autumn. The Subtropical Gyre moves northward from February to March, southward in October, and to the southernmost in around January, while the Subpolar Gyre moves northward in spring, southward in summer, northward again in autumn and reaching the extreme point in winter to the south. The common feature of the interannual and interdecadal variabilities is that the two gyres were weaker and to the north before 1976-1977, while they were stronger and to the south after 1976-1977. The Subpolar Gyre has made a paramount contribution to the variability on interdecadal scales. As is indicated with the Subpolar Gyre strength indices, there was an important shift from weak to strong around 1976-1977, and the correlation coefficient with the North Pacific Decadal Oscillation (PDO) indices was 0.45, which was far better than that between the Subtropical Gyre strength indices and the PDO. Tests show that influenced by small and mesoscale eddies, the magnitude of large-scale gyres strength is strongly dependent on data resolution. But seasonal interannual and interdecadal large-scale variabilities of the two gyres presented with indices is less affected by model resolution. 相似文献
5.
南海暖水季节和年际变化的初步研究 总被引：1，自引：1，他引：1
南海暖水具有明显的季节和年际变化。利用气候平均的COADS资料和NCEP大气资料分析了南海暖水的季节变化及其与海面净热通量的关系,以及由此引起的南海地区大气环流的变化。发现海面净热通量在南海暖水的季节变化过程中起到了主要的作用;冬季无暖水存在时,最大上升气流位于赤道及以南地区的印尼群岛附近,夏季最大上升气流北移到了南海暖水上空,南海暖水上空对流强烈,成为大气的对流活动中心。利用50年逐月的SODA海温资料进行垂直方向的3次样条插值,定义并计算南海暖水的强度指数,分析南海暖水的年际变化,并对南海暖水的几个异常暖年份作了合成分析,探讨了暖水年际变化的形成因素。 相似文献
6.
We have constructed a fine-resolution model with realistic bathymetry to study the spatial and temporal variations of circulation in the Taiwan Strait (TS). The TS model with a resolution of 3～10 km derives its open boundary conditions from a larger-scale model. The QSCAT/NCEP winds and AVHRR SST provide forcing at the sea surface. Because of the high resolution in model grids and forcing, the model achieves a previously unavailable level of agreement with most observations. On biweekly time scales surface-trapped current reversals often lead to Strait transport reversals if the northeasterly wind bursts in winter are sufficiently strong. On seasonal time scales the northward current is the strongest in summer since both summer monsoon and pressure gradient force are northward. The summer northward current appears to be relatively unimpeded by the Changyun Rise (CYR) and bifurcates slightly near the surface. With the arrival of the northeast monsoon in fall, downwind movement of China Coastal Water (CCW) is blocked by the northward current near 25.5°N and 120°E. In winter, the northward current weakens even more as the northeasterly monsoon strengthens. The CCW moves downwind along the western boundary; the CYR blocks part of the CCW and forces a U-shaped flow pattern in the northern Strait. Past studies have failed to reveal an anticyclonic eddy that develops on the northern flank of CYR in winter. On interannual time scales a weakened northeast monsoon during El Niño reduces advection of the cold CCW from the north and enhances intrusion of warm water from the south, resulting in warming in the TS. 相似文献
7.
基于CORA资料的中国海海表面温度季节和年际变化特征分析 总被引：1，自引：0，他引：1
基于1986-2008年的中国近海及邻近海域再分析产品(CORA),采用经验正交函数分解方法(EOF)分析了海表面温度(SST)的季节及年际变化特征,并用相应的SODA、AVHRR以及Levitus资料对CORA做了对比评估。相比于AVHRR而言,CORA资料SST的偏差和均方根误差均小于SODA,相比Levitus资料而言CORA资料温度盐度的均方根误差随深度的变化皆小于SODA。 CORA与SODA资料相比,两者前3个模态的时空分布大体一致,区别在于CORA资料能更好地反映参量的一些细微特征。结果表明,CORA资料能很好的刻画中国近海SST的季节、年际变化特征,尤其是黑潮流经区域SST的局地变化特征。季节EOF第二模态显示的是SST对由风引起的潜热释放的响应特征。第三模态刻画了冬夏转换季的分布特征,主要揭示了东北-西南走向的锋面特征。SST年际变化与ENSO密切相关,区域平均的南海SSTA与Nino指数的吻合程度CORA优于SODA。 相似文献
8.
利用 SeaWiFS卫星遥感叶绿素质量浓度及TRMM微波遥感海表温度产品,研究了南海海表叶绿素a的季节变化特征及其同海表温度的关系。研究结果表明,南海叶绿素质量浓度具有很强的季节变化:通常低叶绿素质量浓度(<0.12 mg. m-3)出现在弱风、高海表温度(>28 °C)的春、夏季节;高叶绿素质量浓度(>0.13 mg·m-3)出现在有较强风速和较低海表温度(<27 °C)的冬季。线性回归分析显示,南海叶绿素质量浓度同海表温度呈显著负相关关系。尽管在南海南部、南海中部、南海西部及吕宋西北部4个代表子区域的显著性有所差异,但都暗示温度变化所反映的垂向层化调控了营养盐质量浓度和浮游植物量变化。可见,温度可能是影响海洋上层稳定程度及垂向交换强度的重要指标,从而可能调控营养盐及浮游植物的变化。 相似文献
9.
利用 Sea WiFS卫星遥感叶绿素质量浓度及TRMM微波遥感海表温度产品, 研究了南海海表叶绿素a的季节变化特征及其同海表温度的关系。研究结果表明, 南海叶绿素质量浓度具有很强的季节变化:通常低叶绿素质量浓度(<0.12 mg·m-3)出现在弱风高海表温度(>28°C)的春、夏季节;高叶绿素质量浓度(>0.13 mg·m-3)通常出现在有较强风速和较低海表温度(<27°C)的冬季。线性回归分析显示, 南海叶绿素质量浓度同海表温度呈显著负相关。尽管在南海南部、南海中部、南海西部及吕宋西北部4个代表子区域的显著性有所差异, 但都暗示温度变化所反映的垂向层化调控了营养盐质量浓度和浮游植物量变化。可见, 温度可能是影响海洋上层稳定程度及垂向交换强度的重要指标, 从而可能调控营养盐及浮游植物的变化。 相似文献
10.
11.
Seasonal and interannual variability of the Subtropical Countercurrent (STCC) in the western North Pacific are investigated
using observations by satellites and Argo profiling floats and an atmospheric reanalysis. The STCC displays a clear seasonal
cycle. It is strong in late winter to early summer with a peak in June, and weak in fall. Interannual variations of the spring
STCC are associated with an enhanced subtropical front (STF) below the surface mixed layer. In climatology, the SST front
induces a band of cyclonic wind stress in May north of the STCC on the background of anticyclonic curls that drive the subtropical
gyre. The band of cyclonic wind and the SST front show large interannual variability and are positively correlated with each
other, suggesting a positive feedback between them. The cyclonic wind anomaly is negatively correlated with the SSH and SST
below. The strong (weak) cyclonic wind anomaly elevates (depresses) the thermocline and causes the fall (rise) in the SSH
and SST, accelerating (decelerating) STCC to the south. It is suggested that the anomalies in the SST front and STCC in the
preceding winter affect the subsequent development of the cyclonic wind anomaly in May. Results from our analysis of interannual
variability support the idea that the local wind forcing in May causes the subsequent variations in STCC. 相似文献
12.
A three-dimensional numerical model is used to simulate sea level and velocity variations in the South China Sea for 1992–1995. The model is driven by daily wind and daily sea surface temperature fields derived from the NCEP/NCAR 40-year reanalysis project. The four-year model outputs are analyzed using time-domain Empirical Orthogonal Functions (EOF). Spatial and temporal variations of the first two modes from the simulation compare favorably with those derived from satellite altimetry. Mode 1, which is associated with a southern gyre, shows symmetric seasonal reversal. Mode 2, which contributes to a northern gyre, is responsible for the asymmetric seasonal and interannual variations. In winter, the southern and northern cyclonic gyres combine into a strong basin-wide cyclonic gyre. In summer, a cyclonic northern gyre and an anticyclonic southern gyre form a dipole with a jet leaving the coast of Vietnam. Interannual variations are particularly noticeable during El Niño. The winter gyre is generally weakened and confined to the southern basin, and the summer dipole structure does not form. Vertical motions weaken accordingly with the basin-wide circulation. Variations of the wind stress curl in the first two EOF modes coincide with those of the model-derived sea level and horizontal velocities. The mode 1 wind stress curl, significant in the southern basin, coincides with the reversal of the southern gyre. The mode 2 curl, large in the central basin, is responsible for the asymmetry in the winter and summer gyres. Lack of the mode 2 contribution during El Niño events weakens the circulation. The agreement indicates that changes in the wind stress curl contribute to the seasonal and interannual variations in the South China Sea. 相似文献
13.
基于东海PN断面近50年的历史水文数据,本文中作者应用一种斜压流函数空间投影的方法分析冲绳海槽北部黑潮水团的季节性和年代际变异.诊断生成的地转经验模态(GEM)显示黑潮中层水的盐度在夏季相对较低,春季达到最高.通过比较1987年之后CTD数据生成的GEM场与1987年之前BOttle数据生成的GEM场,得以证实黑潮的年代际变化特征,即黑潮表层水近20年来温度升高而盐度减小,同时发现黑潮热带水具有盐度增加而中层水具有盐度减小的趋势. 相似文献
14.
A preliminary study on the response of marine primary production to monsoon variations in the South China Sea Basic characteristics 总被引：3，自引：3，他引：0
Seasonal, interannual and interdecadal variations of monsoon over the South China Sea （SCS） directly influence the ocean circulation and the mass transport process, etc. , especially the changes of horizontal circulation pattern and upwelling area. These changes directly influence the nutrient transport and the photosynthesis of phytoplankton, which induce the change of the marine ecosystem in the SCS, including the change of marine primary production in this sea area. On the basis of climatic data for long-time series and primary production estimated by remote sensing, the multi-time scale variations of monsoon, seasonal and interannual variations of primary production, and the response of primary production to monsoon variations were analyzed. Furthermore, the spatio-temporal variations of primary production in different sea areas of the SCS and their relations to the monsoon variations were given. The results showed that the strong southwesterly prevailed over the SCS in summer whereas the vigorous northeasterly in winter. The seasonal primary production in the entire sea area of the SCS also produced a strong peak in winter and a suhpeak in summer. And the seasonal primary production distributions displayed different characteristics in every typical sea area. The variations of the annual and summer averaged primary production in the entire sea area of the SCS showed almost the same rising trend as the intensity of the summer monsoon. Especially for 1998, the summer monsoon reached almost the minimum in the past 54 a when the primary production was also found much lower than any other year （ 1999--2005 ）. The responses of annual primary production to monsoon variation were displayed to different extent in different sea areas of the SCS ; especially it was better in the deep sea basin. Such research activities could be very important for revealing the response of marine ecosystem to the monsoon variations in the SCS. 相似文献
15.
南海混合层深度的季节变化及年际变化特征 总被引：2，自引：0，他引：2
通过分析新的SODA(Simple Ocean Data Assimilation)资料,得到南海混合层时空场的分布特征,剖析了南海混合层深度的季节及年际变化特征。资料分析表明:南海混合层存在着显著的季节和年际变化,且两者的均方差分布存在一定的差异。在季节变化中,冬季混合层在南海北部及西北陆架区深,在南海南部及吕宋冷涡处浅;夏季混合层在南海西北部浅,东南深。南海这种混合层深度分布特征除了与热通量的季节变化有关外,在相当大的程度上与季风引起的Ekman输送及Ekman抽吸有关。混合层深度距平场EOF(Empirical Othorgnal Function)第一模和第二模时间变化的主信号均为周期的年际变化信号,其中第一模态约为3 a,第二模态则有1.8,2.4和4.3 a的3个显著周期。EOF第一模显示混合层深度在南海东南部年际变化幅度最大,且滞后Nino3指数7个月时相关性最好(相关系数为0.422 3);EOF第二模显示在南海南部和北部混合层深度呈反位相变化。 相似文献
16.
《Deep Sea Research Part I: Oceanographic Research Papers》2006,53(5):820-835
Hydrographic data from National Oceanographic Data Center (NODC) and Responsible National Oceanographic Data Centre (RNODC) were used to study the seasonal variability of the mixed layer in the central Bay of Bengal (8–20°N and 87–91°E), while meteorological data from Comprehensive Ocean Atmosphere Data Set (COADS) were used to explore atmospheric forcing responsible for the variability. The observed changes in the mixed-layer depth (MLD) clearly demarcated a distinct north–south regime with 15°N as the limiting latitude. North of this latitude MLD remained shallow (∼20 m) for most of the year without showing any appreciable seasonality. Lack of seasonality suggests that the low-salinity water, which is perennially present in the northern Bay, controls the stability and MLD. The observed winter freshening is driven by the winter rainfall and associated river discharge, which is advected offshore under the prevailing circulation. The resulting stratification was so strong that even a 4 °C cooling in sea-surface temperature (SST) during winter was unable to initiate convective mixing. In contrast, the southern region showed a strong semi-annual variability with deep MLD during summer and winter and a shallow MLD during spring and fall intermonsoons. The shallow MLD in spring and fall results from primary and secondary heating associated with increased incoming solar radiation and lighter winds during this period. The deep mixed layer during summer results from two processes: the increased wind forcing and the intrusion of high-salinity waters of Arabian Sea origin. The high winds associated with summer monsoon initiate greater wind-driven mixing, while the intrusion of high-salinity waters erodes the halocline and weakens the upper-layer stratification of the water column and aids in vertical mixing. The deep MLD in the south during winter was driven by wind-mixing, when the upper water column was comparatively less stable. The deep MLD between 15 and 17°N during March–May cannot be explained in the context of local atmospheric forcing. We show that this is associated with the propagation of Rossby waves from the eastern Bay. We also show that the nitrate and chlorophyll distribution in the upper ocean during spring intermonsoon is strongly coupled to the MLD, whereas during summer river runoff and cold-core eddies appear to play a major role in regulating the nutrients and chlorophyll. 相似文献
17.
Interannual variability of the Kuroshio intrusion in the South China Sea 总被引：13，自引：1，他引：13
Michael J. Caruso Glen G. Gawarkiewicz Robert C. Beardsley 《Journal of Oceanography》2006,62(4):559-575
The interannual variability of intrusions of the Kuroshio into the South China Sea (SCS) is investigated using satellite remote
sensing data supported by in-situ measurements. The mesoscale circulation of the SCS is predominantly wind-forced by the northeast
winter and southwest summer monsoons. Although the region has been studied extensively, considerable uncertainty remains about
the annual and interannual mesoscale nature of the circulation. The frequency and characteristics of Kuroshio intrusions and
their effect on circulation patterns in the northeast SCS are also not well understood. Satellite observations of Sea Surface
Temperature (SST) from the Tropical Rainfall Measuring Mission (TRMM) and the Advanced Very High Resolution Radiometer (AVHRR)
and Sea Surface Height Anomalies (SSHA) from TOPEX/ Poseidon for the period 1997–2005 are used here to analyze the annual
and interannual variability in Kuroshio intrusions and their effects on the region. Analysis of SST and SSHA shows the formation
and characteristics of intrusions vary considerably each year. Typically, the intrusion occurs in the central region of Luzon
Strait and results in an anticyclonic circulation in the northeastern SCS. However, in some years, the intrusion is located
in the northern portion of Luzon Strait and a cyclonic intrusion results. Wind stress and wind stress curl derived from the
National Aeronautics and Space Administration (NASA) QuikSCAT satellite scatterometer are used to evaluate the relationship
between wind stress or wind stress curl and the presence of winter Kuroshio intrusions into the SCS. 相似文献
18.
渤、黄、东海透明度的分布与变化 总被引：6，自引：1，他引：6
本文根据1972～1987年间中国和南朝鲜的海洋调查资料,分析研究了渤、黄、东海海水透明度的分布特征和季节变化,并对其影响因子作了较为详细的讨论。渤、黄、东海海水透明度具有明显的地区差异和季节变化。其基本特征为:近岸和河口区透明度低;远岸和受外海水系影响区高。冬季低;夏季高。控制透明度分布和变化的主要影响因子有:风和潮流的搅拌作用、大陆径流、沿岸和外海流系、沉积物分布和海洋层化等。 相似文献
19.
印尼贯穿流源区马鲁古海与哈马黑拉海水团来源的季节和年际变化 总被引：2，自引：1，他引：1
So far, large uncertainties of the Indonesian throughflow(ITF) reside in the eastern Indonesian seas, such as the Maluku Sea and the Halmahera Sea. In this study, the water sources of the Maluku Sea and the Halmahera Sea are diagnosed at seasonal and interannual timescales and at different vertical layers, using the state-of-the-art simulations of the Ocean General Circulation Model(OGCM) for Earth Simulator(OFES). Asian monsoon leaves clear seasonal footprints on the eastern Indonesian seas. Consequently, the subsurface waters(around 24.5σ_θ and at ～150 m) in both the Maluku Sea and the Halmahera Sea stem from the South Pacific(SP) during winter monsoon, but during summer monsoon the Maluku Sea is from the North Pacific(NP), and the Halmahera Sea is a mixture of waters originating from the NP and the SP. The monsoon impact decreases with depth, so that in the Maluku Sea, the intermediate water(around 26.8σ_θ and at ～480 m) is always from the northern Banda Sea and the Halmahera Sea water is mainly from the SP in winter and the Banda Sea in summer. The deep waters(around27.2σ_θ and at ～1 040 m) in both seas are from the SP, with weak seasonal variability. At the interannual timescale,the subsurface water in the Maluku Sea originates from the NP/SP during El Ni?o/La Ni?a, while the subsurface water in the Halmahera Sea always originates from the SP. Similar to the seasonal variability, the intermediate water in Maluku Sea mainly comes from the Banda Sea and the Halmahera Sea always originates from the SP. The deep waters in both seas are from the SP. Our findings are helpful for drawing a comprehensive picture of the water properties in the Indonesian seas and will contribute to a better understanding of the ocean-atmosphere interaction over the maritime continent. 相似文献
20.
veKdv方程的若干系数在南海北部的地理分布特征及其季节变化分析 总被引：1，自引：1，他引：0
应用中国近海及邻近海域海洋再分析资料(简称CORA)研究南海北部第一模态内波场运动学参数的地理分布特征及其季节变化。首先分析了Brunt-Väisälä频率的统计特征;其次,基于弱非线性变系数扩展Kortewed-de Vries (veKdv)方程模型,计算了它的输入系数,即线性长波相速度,平方和立方非线性系数和频散系数,这些参数可用于定性评估内孤立波传播可能的极性,内孤立波的形态,幅度限制以及传播速度等。分析结果表明,南海北部季节性密度跃层从2月开始出现,最大浮力频率约在20 m。它在6—7月达到最强,自8月开始减弱,在10月消退。另一密度跃层出现在8—11月,最大浮力频率约在80 m,冬季大致在120 m。季节性密度跃层在4—9月十分明显,而8—10月双跃层现象显著,冬季仅出现较弱的第二密度跃层。在1—3月和10—12月海盆深水区最大Brunt-Väisälä频率值要大于陆架浅水区;而在5—9月情况则相反。Brunt-Väisälä频率最大值所在深度随季节变化显著,冬季最深,6—7月则最浅。计算的线性内波相速度、频散系数和幅度放大因子的空间特征主要取决于地形变化;平方(立方)非线性系数与地形关系较小,随季节变化明显,它们主要取决于局地海洋环境特征。通过分析veKdv方程的系数特征,解释了为何在夏季南海北部最容易观测到大振幅内孤立波和在吕宋海峡以东海域难以观测到孤立波的原因。 相似文献