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1.
Observation of the Soya Warm Current using HF ocean radar   总被引:1,自引:1,他引:0  
Three High Frequency (HF) ocean radar stations were installed around the Soya/La Perouse Strait in the Sea of Okhotsk in order to monitor the Soya Warm Current (SWC). The frequency of the HF radar is 13.9 MHz, and the range and azimuth resolutions are 3 km and 5 deg., respectively. The radar covers a range of approximately 70 km from the coast. The surface current velocity observed by the HF radars was compared with data from drifting buoys and shipboard Acoustic Doppler Current Profilers (ADCPs). The current velocity derived from the HF radars shows good agreement with that observed using the drifting buoys. The root-mean-square (rms) differences were found to be less than 20 cm s−1 for the zonal and meridional components in the buoy comparison. The observed current velocity was also found to exhibit reasonable agreement with the shipboard ADCP data. It was shown that the HF radars clearly capture seasonal and short-term variations of the SWC. The velocity of the Soya Warm Current reaches its maximum, approximately 1 m s−1, in summer and weakens in winter. The velocity core is located 20 to 30 km from the coast, and its width is approximately 40 km. The surface transport by the SWC shows a significant correlation with the sea level difference along the strait, as derived from coastal tide gauge records at Wakkanai and Abashiri. Deceased.  相似文献   

2.
中国海和泰国湾海域海平面的经向涛动   总被引:1,自引:0,他引:1  
李立 《海洋学报》2014,36(9):7-17
卫星高度计遥感海面高度距平资料(1992-2012年)的分析结果证实中国海(渤、黄、东海及南海)和泰国湾作为一个半封闭的狭长水域,其海平面存在显著的南北经向涛动。涛动呈现明显的季节性,冬季南高北低,夏季北高南低,以渤海和泰国湾的海平面高差作为涛动的测度,其多年平均波动幅度达63cm,较差超过80cm。时间序列分析显示,在季节尺度上这一涛动几乎完全受东亚季风的支配,表明东亚季风的局地强迫是造成季节涛动的主要原因。进一步的分析发现,除季节波动之外研究海域海平面的经向涛动还存在明显的年际变化。不过,与季节尺度的波动有所不同,经向涛动的年际变化不仅是东亚季风区局地作用的结果,而且与太平洋海盆尺度的大气强迫有关,其作用与季风在同一数量级。涛动的年际变化大致滞后各气候因子两个月。采用多输入线性模型做偏相关分析筛选的结果显示,除东亚季风指数之外,研究海域的海平面涛动指数主要与太平洋的南方涛动指数(SOI)和西太平洋遥相关指数(WP)相关。这表明外部强迫既来自热带,也来自中纬度。南方涛动所导致的赤道海域海平面的东西向年际涛动,以及中纬度西风急流年际波动对西北太平洋海平面的作用,都有可能导致研究海域海平面经向涛动的年际变化,其机制有待进一步探讨。  相似文献   

3.
2000-2008年期间南海海面温度的年际与空间变异   总被引:1,自引:0,他引:1  
通过对2000-2008年更高空间分辨率的南海海面温度(SST)的卫星遥感数据进行经验正交函数(EOF)分析,着重研究21世纪以来整个南海海域SST年际变化的时空变异,并探讨了其与南海海面风场和海面高度的关系,以及期间南海发生的两次负异常事件的特点和成因.SST年际变化的第一模态表现为全海盆同相变化,年际振荡主要发生在...  相似文献   

4.
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   

5.
Seasonal and interannual variations in the East Sakhalin Current (ESC) are investigated using ten-year records of the sea level anomaly (SLA) observed by the TOPEX/POSEIDON (T/P) altimeter. The T/P SLA clearly documents seasonal and interannual variations in the ESC along the east coast of Sakhalin Island, although sea ice masks the region from January to April. Estimates of surface current velocity anomaly derived from T/P SLA are in good agreement with drifting buoy observations. The ESC is strong in winter, with a typical current velocity of 30–40 cm s−1 in December, and almost disappears in summer. Southward flow of the ESC is confined to the shelf and slope region and consists of two velocity cores. These features of the ESC are consistent with short-term observations reported in previous studies. Analysis of the ten-year records of T/P SLA confirms that the structure of the ESC is maintained each winter and the seasonal cycle is repeated every year, although the strength of the ESC shows large interannual variations. Seasonal and interannual variations in the ESC are discussed in relation to wind-driven circulation in the Sea of Okhotsk, using wind stress and wind stress curl fields derived from European Centre for Medium Range Weather Forecasts (ECMWF) reanalysis data and a scatterometer-derived wind product. Seasonal and interannual variations of the anticyclonic eddy in the Kuril Basin are also revealed using T/P SLA.  相似文献   

6.
应用ROMS数值模式配置基本实验模拟了2004年到2006年中国东部海域海平面的季节变化。模拟结果与TOPEX/Poseidon(T/P)卫星高度计观测结果基本一致,海平面年较差从中国沿岸到黑潮路径逐渐变小。将数值模式的风应力项去掉,配置对比实验。与基本实验结果对比发现,对比实验海平面仍然具有季节变化,但是闽浙沿岸和苏北沿岸海平面春夏季异常偏低、秋冬季异常偏高现象消失,中国沿岸向太平洋的海平面变化减弱。春季和秋季,渤、黄海和黑潮附近海平面异于东海的现象减弱。对比实验海平面的年较差的数值明显减小,从近岸向黑潮海平面年较差渐变的过程消失。整个渤黄海的海平面年较差近似。对比实验海平面年较差占基本实验海平面年较差比率从近岸向黑潮路径逐渐增大。  相似文献   

7.
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   

8.
To address the mechanisms controlling halocline variability in the Beaufort Sea, the relationship between halocline shoaling/deepening and surface wind fields on seasonal to decadal timescales was investigated in a numerical experiment. Results from a pan-Arctic coupled sea ice-ocean model demonstrate reasonable performances for interannual and decadal variations in summer sea ice extent in the entire Arctic and in freshwater content in the Canada Basin. Shelf-basin interaction associated with Pacific summer and winter transport depends on basin-scale wind patterns and can have a significant influence on halocline variability in the southern Beaufort Sea. The eastward transport of fresh Pacific summer water along the northern Alaskan coast and Ekman downwelling north of the shelf break are commonly enhanced by cyclonic wind in the Canada Basin. On the other hand, basin-wide anti-cyclonic wind induces Ekman upwelling and blocks the eastward current in the Beaufort shelf-break region. Halocline shoaling/deepening due to shelf-water transport and surface Ekman forcing consequently occur in the same direction. North of the Barrow Canyon mouth, the springtime down-canyon transport of Pacific winter water, which forms by sea ice production in the Alaskan coastal polynya, thickens the halocline layer. The model result indicates that the penetration of Pacific winter water prevents the local upwelling of underlying basin water to the surface layer, especially in basin-scale anti-cyclonic wind periods.  相似文献   

9.
Sea level changes in the Baltic Sea are dominated by internal, short-term variations that are mostly caused by the ephemeral nature of atmospheric conditions over the Baltic area. Tides are small and their influence decreases from western parts of the Baltic Sea to the Baltic Proper. Superimposed to the large short-term sea level changes (up to few decimeters from day to day) are seasonal and interannual variations (centimeters to decimeters). This study focuses on the comparison of sea surface heights obtained from observations and from a high resolution oceanographic model of the Baltic Sea. From this comparison, the accuracy of the modeled sea surface variations is evaluated, which is a necessary precondition for the further use of the oceanographic model in geodetic applications. The model reproduces all observed Baltic sea level variations very reliably with an accuracy of 5 to 9 cm (rms) for short-term variations (up to 2 months) and 8 cm (rms) for long-term variations (>2 months). An additional improvement of the model can be attained by including long-period sea level variations of the North Sea. The model performs well also in the case of extreme sea level events, as is shown for a major storm surge that occurred at the southern coast of the Baltic Sea in November 1995.  相似文献   

10.
Using the high-resolution Hybrid Coordinate Ocean Model and the Navy Coupled Ocean Data Assimilation Global 1/12° Analysis (GLBa0.08), and the Objectively Analyzed Air–Sea Fluxes and the International Satellite Climatology Cloud Project products, we investigated the seasonal and interannual evolutions of heat budget, including the pseudo-heat content change, the net air–sea heat flux and the eddy heat transport (EHT), based on the time-dependent heat budget analysis in the western Pacific warm pool (WPWP). The results show that the pseudo-heat content change has significant semi-annual variation, which peaks in April–May and September. There is strong positive feedback between EHT and the net air–sea heat flux. EHT is important in balancing the sea surface heat flux into the WPWP. The seasonal EHT variability is dominated by its meridional component. On the interannual time scale, the zonal and vertical components of EHT show comparable amplitudes with the meridional one. The observed net air–sea heat flux in the WPWP is highly correlated with EHT and the pseudo-heat content change on the interannual time scale. The net air–sea heat flux leads the pseudo-heat content change by about half a month and leads EHT by about one month. The variations of the air–sea heat flux and EHT are connected to the El Niño Southern Oscillation events: during the development of El Niño (La Niña) events, the warm pool expanded eastward (retreated westward), the net air–sea surface flux into the WPWP increased (decreased) and EHT enhanced (weakened) significantly.  相似文献   

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