Forecasts of South China Sea surface temperature anomalies using the Nio indices and dipole mode index as predictors     

陈海英  方国洪  尹宝树  王永刚  魏泽勋 《中国海洋湖沼学报》2010,(1)

Based on an empirical orthogonal function (EOF) analysis of the monthly NCEP Optimum Interpolation Sea Surface Temperature (OISST) data in the South China Sea (SCS) after removing the climatological mean and trends of SST,over the period of January 1982 to October 2003,the corresponding TCF correlates best with the Dipole Mode Index (DMI),Nio1+2,Nio3.4,Nio3,and Nio4 indices with time lags of 10,3,6,5,and 6 months,respectively.Thus,a statistical hindcasts in the prediction model are based on a canonical correlation analysis (CCA) model using the above indices as predictors spanning from 1993/1994 to 2003/2004 with a 1-12 month lead time after the canonical variants are calculated,using data from the training periods from January 1982 to December1992.The forecast model is successful and steady when the lead times are 1-12 months.The SCS warm event in 1998 was successfully predicted with lead times from 1-12 months irrespective of the strength or time extent.The prediction ability for SSTA is lower during weak ENSO years,in which other local factors should be also considered as local effects play a relatively important role in these years.We designed the two forecast models:one using both DMI and Nio indices and the other using only Nio indices without DMI,and compared the forecast accuracies of the two cases.The spatial distributions of forecast accuracies show different confidence areas.By turning off the DMI,the forecast accuracy is lower in the coastal areas off the Philippines in the SCS,suggesting some teleconnection may occur with the Indian Ocean in this area.The highest forecast accuracies occur when the forecast interval is five months long without using the DMI,while using both of Nio indices and DMI,the highest accuracies occur when the forecast interval time is eight months,suggesting that the Nio indices dominate the interannual variability of SST anomalies in the SCS.Meanwhile the forecast accuracy is evaluated over an independent test period of more than 11 years (1993/94 to October 2004) by comparing the model performance with a simple prediction strategy involving the persistence of sea surface temperature anomalies over a 1-12 month lead time (the persisted prediction).Predictions based on the CCA model show a significant improvement over the persisted prediction,especially with an increased lead time (longer than 3 months).The forecast model performs steadily and the forecast accuracy,i.e.,the correlation coefficients between the observed and predicted SSTA in the SCS are about 0.5 in most middle and southern SCS areas,when the thresholds are greater than the 95% confidence level.For all 1 to 12 month lead time forecasts,the root mean square errors have a standard deviation of about 0.2.The seasonal differences in the prediction performance for the 1-12 month lead time are also examined.  相似文献   

对吕宋海峡深水瀑布的重新认识     

朱耀华  孙俊川  魏泽勋  王永刚  方国洪  曲堂栋 《海洋学报(英文版)》2017,36(5):1-8

On the basis of the latest version of a U.S. Navy generalized digital environment model(GDEM-V3.0) and World Ocean Atlas(WOA13), the hydraulic theory is revisited and applied to the Luzon Strait, providing a fresh look at the deepwater overflow there. The result reveals that:(1) the persistent density difference between two sides of the Luzon Strait sustains an all year round deepwater overflow from the western Pacific to the South China Sea(SCS);(2) the seasonal variability of the deepwater overflow is influenced not only by changes in the density difference between two sides of the Luzon Strait, but also by changes in its upstream layer thickness;(3) the deepwater overflow in the Luzon Strait shows a weak semiannual variability;(4) the seasonal mean circulation pattern in the SCS deep basin does not synchronously respond to the seasonality of the deepwater overflow in the Luzon Strait.Moreover, the deepwater overflow reaches its seasonal maximum in December(based on GDEM-V3.0) or in fall(October–December, based on the WOA13), accompanied by the lowest temperature of the year on the Pacific side of the Luzon Strait. The seasonal variability of the deepwater overflow is consistent with the existing longest(3.5 a) continuous observation along the major deepwater passage of the Luzon Strait.  相似文献   

基于双矩形海湾模型的泰国湾潮汐潮流研究          下载免费PDF全文

吴頔  方国洪  腾飞  崔欣梅 《海洋科学进展》2013,31(4)

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海洋水文物理学的研究     

毛汉礼  管秉贤  方国洪 《海洋科学》1979,3(S1):45-48

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杭州湾潮流湍应力和涡动粘性的估算   总被引：3，自引：1，他引：3       下载免费PDF全文

李身铎  曹德明  方国洪 《海洋学报》1985,7(4):412-422

本文依据动量方程,采用潮汐和潮流观测资料对杭州湾5个断面的湍应力和涡动粘性进行了估算,计算所得海底拖曳系数平均为0.67×10-3,湍应力振幅垂直廓线接近线性而略呈下凹,位相随离海底距离的增大而延迟,垂直涡动粘性系数在中层偏下达最大,该层平均约为60厘米2/秒。  相似文献   

潮汐摩擦的非线性效应及黄海潮能消耗的研究     

方国洪 《海洋科学》1979,3(S1):105-106

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渤海、黄海和东海的潮余流特征及其与近岸环流输送的关系   总被引：1，自引：0，他引：1  

赵保仁  方国洪  曹德明 《海洋科学集刊》1995,(36):1-11

渤海、黄海和东海是西北太平洋陆缘海,有宽广的大陆架,太平洋潮波长驱直入,在大陆架海域形成显著的潮汐运动,由此而产生的潮余流输送在许多地区显示出重要作用。已有很多学者(方国洪等,1985;黄祖柯,1992)用数值方法计算过渤海的潮波运动,并给出了那里的潮余流分布。渤海的潮余流计算大体上有两种方法:(1)用二维或三维潮波运动方程组计算潮汐和潮流,然后再计算欧拉潮余流(方国洪、杨景飞,1985;于克俊、张法高,1987;黄祖柯,1992);(2)以弱非线性三维拉格朗日平均流理论为基础,计算拉格朗日潮余流,它不仅包括最基本的欧拉余流,而且还包括在浅水比较显著(与欧拉余流同量级)的斯托克斯漂移速度和高阶的拉格朗日漂移速度订正值(郑连远,1992;王辉等，1993)。上述两种方法理应给出大体相近的潮余流分布,但从现有的计算结果来看,这两种方法在渤海给出了几乎完全相反的潮余流输送。 汤毓祥(1990)曾计算过南黄海和东海大陆架区的M2分潮余流,并考虑了斯托克斯速度漂移对它的影响,所得结果和已知的南黄海环流概况颇有相似之处,但由于计算边界取在东海大陆架外缘,那里的潮余流可能失真较大。Chio (1980) 也曾给出过渤海、黄海和东海大陆架区的欧拉潮余流分布,但由于他的开边界也取在东海大陆架外缘,面且他给出的潮汐、潮流数值在靠近中国大陆一侧,误差较大,因此所得潮余流也不能令人满意。 最近,我们完成了包括渤海、黄海和东海全海区的潮汐、潮流二维数值计算工作(Zhao et al,1993),与实测资料相比,其结果达到的准确程度,无论在潮位还是在潮流方面都比较好。本文以这一数值计算结果为基础,给出了渤海、黄海和东海全海区的潮余流分布，同时还讨论了潮余流与近岸环流的关系。  相似文献   

南海北部潮汐潮流的数值模型   总被引：4，自引：1，他引：4  

曹德明  方国洪 《热带海洋》1990,9(2):63-70

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利用伴随法优化非线性潮汐模型的开边界条件Ⅱ.黄海、东海潮汐资料的同化试验   总被引：12，自引：4，他引：12  

韩桂军  方国洪  马继瑞  刘克修  李冬 《海洋学报》2001,23(2):26-31

本研究基于最优控制理论,采用变分数据同化法,通过建立伴随模型,把观测资料同化到陆架海域潮汐数值模型中去,优化开边界条件,以便提高数值预报的精度.潮汐模型的控制方程为考虑平流项、非线性底摩擦和侧向涡动粘性项的非线性浅水方程组.在第Ⅰ部分建立伴随模型和进行“孪生”数值试验的基础上,给出利用验潮站的水位资料以及TOPEX/Poseidon卫星测高数据在黄海、东海进行变分数据同化试验的数值结果.试验表明利用上述资料对模型进行变分同化校正是可行的.  相似文献   

一种二维和三维嵌套海洋流体动力学数值模式及其在北部湾潮汐和潮流…          下载免费PDF全文

朱耀华  方国洪 《海洋与湖沼》1993,24(2):117-125

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