The link between interannual variation of the South China Sea summer monsoon onset and summer precipitation in Shandong Province

Relationship between the onset date of South China Sea (SCS) summer monsoon and the summer rainfall in Shandong Province was examined by comprehensive analysis to establish a conceptual model of the link. If the summer monsoon occurs earlier, the 500 hPa level would induce the teleconnection of Eurasian pattern in the summer (June-August), which indicates that the western Pacific subtropical high is displaced northward further than usual, the Siberian high is intensified and the Okhotsk low is deepened. Under such circumstance, Shandong, located in the west side of the subtropical high and in front of the mid-Siberia high, would be expected to have a wet summer because it is quite possible for cold and warm air to meet and interact with each other in Shandong. Statistical analysis revealed that the 500 hPa anomalies over Korea and Japan were sensitive to the SCS monsoon onset date and very important to precipitation in Shandong, and that the convective activities over the deep water basin in the SCS in 24-26 pentads significantly influenced the position of the ridge line of the western Pacific subtropical high. These findings yielded better understanding of the causative mechanisms involved in the precipitation generation, so that the knowledge gained can possibly be applied for long-lead forecast.     

An Alternative Index for the Onset of the Summer Monsoon over the South China Sea

1　Introduction　TheindicesfortheAsianmonsoonhavebeenstud iedinmanyworks .Recently ,thechoiceofpropermonsoonindiceshasreceivedexceptionalattentionandraisedcontroversy (WebsterandYang ,1 992 ;Goswa mietal.,1 999;Goswami,2 0 0 0 ;Wang ,2 0 0 0 ) .Us ingzona…     

Circulation patterns of summer monsoon corresponding to two kinds of indices over the South China Sea

The characteristics of circulation corresponding to two kinds of indices of summer monsoon onset over the South China Sea (SCS) have been discussed using the reanalysis data of the National Centers for Environmental Prediction-National Center for Atmospheric Research. It is found that there are two patterns of deep convection that occur at different locations and influence the summer monsoon onset over the SCS. One is over the Asia continent and the western Pacific corresponding to the southwesterly of summer monsoon prevailing over the northern and central part of the SCS, while the other is near the Philippines that affects the westerly summer monsoon as prevailing over the central and southern southern part of the SCS. Since these two kinds of convection affecting the summer monsoon onset do not always occur together, thus the summer monsoon onset time is different when determined by various indices.     

Response of the South China Sea summer monsoon onset to air-sea heat fluxes over the Indian Ocean

We objectively define the onset date of the South China Sea (SCS) summer monsoon, after having evaluated previous studies and considered various factors. Then, interannual and interdecadal characteristics of the SCS summer monsoon onset are analyzed. In addition, we calculate air-sea heat fluxes over the Indian Ocean using the advanced method of CORARE3.0, based on satellite remote sensing data. The onset variation cycle has remarkable interdecadal variability with cycles of 16 a and 28 a. Correlation analysis between air-sea heat fluxes in the Indian Ocean and the SCS summer monsoon indicates that there is a remarkable lag correlation between them. This result has important implications for prediction of the SCS summer monsoon, and provides a scientific basis for further study of the onset process of this monsoon and its prediction. Based on these results, a linear regression equation is obtained to predict the onset date of the monsoon in 2011 and 2012. The forecast is that the onset date of 2011 will be normal or 1 pentad earlier than the normal year, while the onset date in 2012 will be 1-2 pentads later.     

An analysis of the causes of decadal variations of rainfall in Shandong in summer

The precipitation in Shandong in July, August as well as the whole summer (JJA) and the corresponding 500hPa geopotential height fields are analyzed by means of the SVD (singular value decomposition) methodology. It is found that the general circulations in East Asia and the Western Pacific underwent decadal changes around 1979. The geopotential height, in particular over key areas like the South China Sea and the Philippines, increased after 1979. Corresponding to the changes in the geopotential height, the rainfall in Shandong started to decrease around 1979. The synthesized analysis shows that when the geopotential height at 500hPa level decreases in the key areas, the Western Pacific subtropical high shifts northward and an anticyclonic anomalous cell enforces the southerly flow over Shandong-Korea-Japan, Shandong could experience a wet period. A dry period is likely to occur when the geopotential height increases in these key areas, the subtropical high moves southward or expands westward to a great distance, and a cyclonic anomalous cell controls Shandong. Respective conceptual models for the causative mechanism are obtained for the cases of July, August and the whole summer (JJA).     

Annual and interannual variability of scatterometer ocean surface wind over the South China Sea

To investigate the annual and interannual variability of ocean surface wind over the South China Sea (SCS), the vector empirical orthogonal function (VEOF) method and the Hilbert-Huang transform (HHT) method were employed to analyze a set of combined satellite scatterometer wind data during the period from December 1992 to October 2009. The merged wind data were generated from European Remote Sensing Satellite (ERS)-1/2 Scatterometer, NASA Scatterometer (NSCAT) and NASA’s Quick Scatterometer (QuikSCAT) wind products. The first VEOF mode corresponds to a winter-summer mode which accounts for 87.3% of the total variance and represents the East Asian monsoon features. The second mode of VEOF corresponds to a spring-autumn oscillation which accounts for 8.3% of the total variance. To analyze the interannual variability, the annual signal was removed from the wind data set and the VEOFs of the residuals were calculated. The temporal mode of the first interannual VEOF is correlated with the Southern Oscillation Index (SOI) with a four-month lag. The second temporal interannual VEOF mode is correlated with the SOI with no time lag. The time series of the two interannual VEOFs were decomposed using the HHT method and the results also show a correlation between the interannual variability and El Niño-Southern Oscillation (ENSO) events.     

Modulation of tropical cyclogenesis over the South China Sea by ENSO Modoki during boreal summer

This study examines the modulation of tropical cyclogenesis over the South China Sea(SCS) by the El Nio-Southern Oscillation(ENSO) Modoki during the boreal summer. Results reveal that there were more tropical cyclones(TCs) formed over the SCS during central Pacific warming years and less TC frequency during central Pacific cooling years. How different environmental factors(including low-level relative vorticity, mid-level relative humidity, vertical wind shear, and potential intensity) contribute to this influence is investigated, using a genesis potential(GP) index developed by Emanuel and Nolan. Composite anomalies of the GP index are produced for central Pacific warming and cooling years separately, which could account for the changes of TC frequency over the SCS in different ENSO Modoki phases. The degree of contribution by each factor is determined quantitatively by producing composites of modified indices in which only one of the contributing factors varies, with the others set to climatology. The results suggest that the vertical wind shear and low-level relative vorticity, which are associated with the ENSO Modoki-induced anomalous circulations in Matsuno-Gill patterns, make the largest contributions to the ENSO Modoki modulation of tropical cyclogenesis over the SCS as implied by the GP index. These results highlight the important roles of dynamic factors in the modulation of TC frequency over the SCS by the ENSO Modoki during the boreal summer.     

An approach to prediction of the South China Sea summer monsoon onset

In the present paper, correlation between the South China Sea summer monsoon （SCSSM） onset and heat content in the upper layer of the warm pool in the western Pacific Ocean is examined using the Scripps Institution of Oceanography dataset for the period of 1955-1998 and an approach to prediction the SCSSM onset is proposed. Correlation showes that there exists interdecadal variability of the SCSSM onset demarcated by 1970 with the largest correlation coefficient in the area west of the center of the warm pool rather than near its centers, implying certain effect from other factors involved besides ENSO. As the correlation is poor for the period before 1970, the heat content anomaly of the warm pool after 1970 is used to indicate early or late onset of the SCSSM beforehand. An ideal representative area （1°×1°） for the warm pool heat content was determined with its center at 3°N/138°E. The nearest TAO （TAO-Tropical Atmosphere Ocean-array） mooring to the center is at 2°N/137°E, and chosen to calculate the heat content for prediction. It is suggested that the TAO mooring at 2°N/137°E could be used to predict the SCSSM onset with the heat content in the upper layer, if the correlation between the SCSSM onset and the heat content of the warm pool runs like that of after 1970. On the other hand, if the situation does like the one before 1970, the representative station is determined at 13°S/74°E with relatively poor correlation, meaning that the warm pool in the western Pacific Ocean plays more important role in the SCSSM onset than the Indian Ocean.     

SEAWATER FLUX OF THE SOUTH CHINA SEA

The South China Sea water can be divided according to depth into three boxes by the pycnoclineand a sill.Using a box model with matter balance,the net seawater fluxes were calculated to be317.9×10~4 m~3/s in box Ⅰ for the upper homogeneous layer outflowing to the adjoining oceans;67×10~4 m~3/s in box Ⅲ for the water entering the basin;240×10~4 m~3/s in box Ⅱ for water entering theSouth China Sea.The upward speed of basin water was calculated to be 8.4×10~(-5) cm/s and that ofseawater flowing up along the pycnocline was calculated to be 8.9×10~(-5) cm/s.     

Statistical Analysis of Tropical Disturbances over the South China Sea During 1997-2006

Tropical disturbances over the South China Sea (SCS) during the period of 1997-2006 are analyzed using the Tropical Storm and Hurricane WX products. A total of 158 tropical disturbances were formed over the SCS from 1997 to 2006, with 54 developing tropical disturbances which developed into tropical depressions and 104 non-developing tropical disturbances which never developed into tropical depressions. The development rate of tropical disturbances into tropical depressions was 34.18% in these ten years. During the period of this study, total annual numbers of tropical disturbances and developing tropical disturbances over the SCS had significant decreasing trends; however, the development rate of tropical disturbances had an insignificant increasing trend.     

NUMERICAL STUDY ON THE INTERANNUAL OSCILLATION OF SEA SURFACE TEMPERATURE IN THE SOUTH CHINA SEA

A two and a half layer oceanic model of wind-driven, thermodynamical general circulation is appliedto study the interannual oscillation of sea surface temperature (SST) in the South China Sea (SCS). Themodel consists of two active layers: the upper mixed layer (UML) and the seasonal thermocline, with themotionless abyss beneath them. The governing equations which include momentum, continuity and sea.temperature for each active layer, can describe the physics of Boussinseq approximation, reduced gravityand equatorial β-plane. The formulas for the heat flux at the surface and at the interface between twoactive layers are designed on the Haney scheme. The entrainment and detrainment at the bottom of theUML induces vertical transport of mass,momentum and heat, and couples of dynamic andthermodynamic effect.Using leap-frog integrating scheme and the Arakawa-C grid the model is forced bya time-dependent wind anomaly stress pattern obtained from category analysis of COADS. The numerical results indicate that t     

Dimethylsulfide in the South China Sea

ＩＮＴＲＯＤＵＣＴＩＯＮＧｒｅａｔｅｆｆｏｒｔｓｗｅｒｅｄｅｖｏｔｅｄｒｅｃｅｎｔｌｙｔｏｓｔｕｄｙｉｎｇｄｉｍｅｔｈｙｌｓｕｌｆｉｄｅ(ＤＭＳ)ｄｉｓｔｒｉｂｕｔｉｏｎｉｎｓｅａｗａｔｅｒ,ａｓｉｔａｃｃｏｕｎｔｓｆｏｒｔｈｅｍａｊｏｒｐａｒｔｏｆｔｈｅｓｕｌｆｕｒｆｌｕｘｆｒｏｍｔｈｅｏｃｅａｎｓｔｏｔｈｅａｔｍｏｓｐｈｅｒｅ.Ｍｏｒｅｏｖｅｒ,ｉｔｓｏｘｉｄａｔｉｏｎｐｒｏｄｕｃｔｓｉｎｔｈｅａｔｍｏｓｐｈｅｒｅｍａｙｉｎｆｌｕｅｎｃｅｅｎｖｉｒｏｎｍｅｎｔａｌａｃｉｄｉｆｉｃａｔｉｏｎａｎｄ…     

STUDY OF WATER—TRANSPORT THROUGH SOME MAIN STRAITS IN THE EAST CHINA SEA AND SOUTH CHINA SEA

OCCAM global ocean model results were applied to calculate the monthly water transport through 7 straits around the East China Sea(ECS)and the South china Sea(SCS).Analysis of the features of velocity profiles and their variations in the Togara Strait,Luzon Strait and Eastern Taiwan Strait showed that;1)the velocity profiles had striped pattern in the Eastern Taiwan Strait,where monthly flux varied from 22.4 to 28.1 Sv and annual mean was about 25.8 Sv;2)the profiles of velocity in the Togara Strait were characterized by core structure,and monthly flux varied from 23.3 to 31.4 Sv,with annual mean of about 27.9 Sv;3)water flowed from the SCS to the ECS in the Taiwan Strait,with maximum flux of 3.1 Sv in July and minimum of 0.9 Sv in November;4)the flux in the Tsushima Strait varied by only about 0.4 Sv by season and its annual mean was about 2.3 Sv;5)Kuroshio water flowed into the SCS in the Luzon Strait throughout the year and the velocity profiles were characterized by multi-core structure.The flux in the Luzon Strait was minimun in June(about 2.4 Sv)and maximum in February(about 9.0 Sv),and its annual mean was 4.8 Sv;6)the monthly flux in the Mindoro Strait was maximum in December(3.0 Sv)and minimum in June(Only 0.1 Sv),and its annual mean was 1.3 Sv;7)Karimata Strait water flowed into the SCS from May to August,with maximum in-flow flux of about 0.75 Sv in June and flowed out from September to April at maximum outflow flux of 3.9 Sv in January.The annual mean flux was about 1.35 Sv.     

Role of Ekman transport versus Ekman pumping in driving summer upwelling in the South China Sea

Relative roles of Ekman transport and Ekman pumping in driving summer upwelling in the South China Sea (SCS) are examined using QuikSCAT scatterometer wind data. The major upwelling regions in the SCS are the coastal regions east and southeast of Vietnam (UESEV), east and southeast of Hainan Island (UESEH), and southeast of Guangdong province (USEG). It is shown that the Ekman transport due to alongshore winds and Ekman pumping due to offshore wind stress curl play different roles in the three upwelling systems. In UESEV, Ekman pumping and Ekman transport are equally important in generating upwelling. The Ekman transport increases linearly from 0.49 Sv in May to 1.23 Sv in August, while the Ekman pumping increases from 0.36 to 1.22 Sv during the same period. In UESEH, the mean estimates of Ekman transport and Ekman pumping are 0.14 and 0.07 Sv, respectively, indicating that 33% of the total wind-driven upwelling is due to Ekman pumping. In USEG, the mean Ekman transport is 0.041 Sv with the peak occurring in July, while Ekman pumping is much smaller (0.003 on average), indicating that the upwelling in this area is primarily driven by Ekman transport. In the summers of 2003 and 2007 following El Niño-Southern Oscillation (ENSO) events, both Ekman transport and Ekman pumping decrease in UESEV due to the abnormally weak southwest monsoon. During the same events, however, Ekman transport is slightly enhanced and Ekman pumping is weakened in UESEH and USEG.     

海面温度对南海台风强度的影响

【目的】分析海面温度(sea surface temperature,SST)对南海台风强度的影响。【方法】以南海为研究区域,以中国气象局热带气旋资料中心热带气旋最佳路径数据集为基础,利用Savitzky-Golay卷积平滑算法和多项式插值算法将台风数据进行插值,对强化值和SST值在南海区域的网格单元进行平均,建立模型并对其做回归分析,分析台风强度强化程度与SST模型之间的关系,以及检验模型残差的分布。通过数据提供的台风轨迹的增强率,来检验SST对台风强度变化的影响。【结果】建立台风强化值与SST之间的回归模式,平均而言,平均SST每增加1℃,台风强度强化度增加12.5%。该模型具有统计学意义,即台风高强度强化值与高海温值相关。【结论】本研究建立的统计模型对南海台风强度的预报有较好的指示效果。     

南海海域数种海藻总脂质及脂肪酸含量的比较

研究南海海域盛产的四种褐藻(海带、裙带菜、昆布和亨氏马尾藻)、三种红藻(紫菜、沙菜和江蓠)及来自南海三个不同海区(南沙、惠来和南澳)亨氏马尾藻的总脂质及脂肪酸含量干重,并重点比较其多不饱和脂肪酸的含量.结果表明,供试褐藻类海藻总脂质含量ω在1.81%～6.11%之间,红藻类海藻的总脂质含量ω在1.44%～3.96%之间;紫菜中含有7.548mg/g(干重,下同)的亚油酸(C182);海带含丰富C181,达5.592mg/g;花生四烯酸(C204)在裙带菜中含量为1.606mg/g;在供试藻种中,昆布的EPA(C20.5)和DHA(C226)含量最高,测定值为608μg/g和689μg/g.     

Anomalies of asian summer monsoon related to ssta in the south China Sea and the tropical pacific

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＳｏｕｔｈＣｈｉｎａＳｅａ(ＳＣＳ)ｉｓａｐａｒｔｌｙ ｅｎｃｌｏｓｅｄｏｃｅａｎｂａｓｉｎｏｖｅｒｌａｉｄｂｙａｐｒｏｎｏｕｎｃｅｄｍｏｎｓｏｏｎｓｕｒｆａｃｅｗｉｎｄ .Ｐａｓｔｓｔｕｄｉｅｓ (Ｃｈｅｎｅｔａｌ.,1 991 ;ＤｉｎｇａｎｄＭｕｒａｋａｍｉ,1 994 ;Ｙａｎ ,1 997;ＬｉａｎｇＢｉｑｉ,1 991 ;ＬｉａｎｇＪｉａｎｙｉｎ ,1 991 )ｉｎｄｉｃａｔｅｔｈａｔａｈｕｇｅｗａｒｍｗａｔｅｒｐｏｏｌｊｏｉｎｔｌｙｃｏｎｔｒｉｂｕｔｅｄｂｙｔｈｅｗｅｓｔｅｒｎＰａｃｉｆｉｃ ,ｅａ…     

论我国南海资源的特点及开发利用对策

南海我国可管辖的海域面积近 2 0 0万km2 ,具有丰富的生物、油气、矿产等资源 ,是我国经济与社会可持续发展的强大支持和保障因素 ,具有海域面积大、资源丰富、区位优势明显、未来开发潜力大等特点。应从强化“寸海寸金”的海洋国土意识出发 ,通过创新管理体制和运行机制 ,建立强有力的海上统一执法队伍 ,按照统一规划、相对集中、由远及近的原则实施重点区域开发战略 ,全面提升南海国土资源开发利用的水平和效益     

The regional air-sea coupled oscillation in the South China Sea

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＳｏｕｔｈＣｈｉｎａＳｅａ (ＳＣＳ)ｉｓａｕｎｉｑｕｅｓｅｍｉ ｅｎｃｌｏｓｅｄｄｅｅｐｏｃｅａｎｂａｓｉｎｌｏｃａｔｅｄｎｅａｒｔｈｅｗｅｓｔ ｅｒｎｐｅｒｉｐｈｅｒｙｏｆｔｈｅＰａｃｉｆｉｃＯｃｅａｎ .Ｓｐｒｅａｄｉｎｇｆｒｏｍｔｈｅｅｑｕａｔｏｒｔｏ 2 0°Ｎａｎｄｓｐａｎｎｉｎｇｚｏｎａｌｌｙａｂｏｕｔ1 5°Ｎ ,ｔｈｅＳＣＳｌｉｅｓｂｅｔｗｅｅｎｔｈｅＳｏｕｔｈＣｈｉｎａｃｏａｓｔａｎｄｔｈｅｍａｒｉｔｉｍｅｃｏｎｔｉｎｅｎｔ.ＴｈｅＳＣＳｂｏｔｔｏｍｔｏｐｏｇｒ…     

STUDY ON THE DISSOLVED OXYGEN FLUX IN THE SOUTH CHINA SEA

xiODUonONThemaoreleInent(oxygen)ofldeinthemarineeresySteInisCycledalongapartho-larrouteinWhwhthethetcanbedrawnfromtheexternlenvirDnmentintoorgan-isim,andthenberetumedtotheenvbonmentfromtheorganisrns.TheDocontentinseawatCfisinIlUentalbyorganisms,imtS,temPeratureandoxidation.So,studyonDoisoftoortanceinoasnographyastheDofluxisofgreatsignfonceinmarinebiogeochdricalcydes.'MareRIAnooMEmOorlnthisstudy,datafroml98O~l992multi-disdplinaryinvestigationsinthecenthel,northeastem,andsouthernSrswe…