Late Quaternary Upwelling Intensity and East Asian Monsoon Forcing in the South China Sea     

Zhimin Jian  Baoqi Huang  Wolfgang Kuhnt  Hui-Ling Lin 《Quaternary Research》2001,55(3):363

Foraminifera from two cores off eastern Vietnam and the northwestern Philippines, where modern summer and winter monsoon-driven upwelling occurs in the South China Sea, respectively, were analyzed to evaluate the changes in paleoproductivity and upper water structure over the last 220,000 yr. We observed enhanced organic carbon flux and a shoaled thermocline when upwelling intensified off eastern Vietnam during interglacial ages and off the northwestern Philippines during glacial ages. This indicates that the East Asian summer monsoon increased while the winter monsoon decreased during interglacial ages. Particularly, the upwelling reached a maximum off eastern Vietnam during late marine isotopic stage (MIS) 5 and off the northwestern Philippines during MIS 2, implying that the summer monsoon decreased gradually since MIS 5 while the winter monsoon displayed an opposite trend. The variations in upwelling proxies exhibit a distinct cyclicity with frequencies near 41,000 yr and 23,000 yr off eastern Vietnam, in contrast to a strong frequency peak near 100,000 yr off the northwestern Philippines. We suggest that the East Asian summer monsoon has been forced by changes in solar insolation associated with precession and obliquity, while ice-volume forcing is probably a primary factor in determining the strength and timing of the East Asian winter monsoon but with less important insolation forcing.  相似文献   

On the impossibility of the co-existence of monsoons and severe storm surges in the Bay of Bengal     

Tad S. Murty  Venkata R. Neralla 《Natural Hazards》1992,6(3):281-285

The problem of storm surges is introduced briefly. The utility of passive microwave observations to study this phenomenon is pointed out. The reasons for the nonoccurrence of severe surges in the Bay of Bengal, during monsoon regimes, is discussed in this paper. It was demonstrated that the predominant reason for lack of severe surges over the Bay of Bengal coast is due to the absence of weak wind shear during monsoon seasons.Atmospheric Environment Service, Ice Center, Environment Canada, 373 Sussex Drive, Ottawa, Ontario, Canada K1A OH3.  相似文献   

寒潮期间高空波动与东亚急流的相互作用   总被引：5，自引：9，他引：5  

高守亭  陶诗言  丁一汇 《大气科学》1992,16(6):718-724

本文分析了东亚寒潮爆发过程中,高空波动和高空急流的相互作用,得出如下结果:(1)高空波动的动量和热通量输送,使高空急流迅速加速并同时导致急流入口区质量环流的加强.(2)质量环流引起中高纬度对流层顶下沉并使高空锋区加强.(3)对流层顶下沉和高空锋区的加强促使平流层下层的气流沿对流层顶折叠处下伸进入对流层,造成对流层中、上部层结及位涡分布的改变.(4)位涡分布的改变制约了斜压波发展的能量源,致使高空波动减弱.  相似文献   

中国华北旱涝与印度夏季风降水的遥相关分析   总被引：17，自引：0，他引：17  

郭其蕴 《地理学报》1992,47(5):394-402

本文根据1871—1986年共116年印度夏季风期（6—9月）雨量与中国华北东部旱涝级别资料研究了两个地区旱涝关系的变化。发现在1921—1950年关系减弱,而1891-1920和1951—1980年关系均较密切。利用相应时期北半球海平面气压图及赤道东太平洋海温资料,讨论了两个地区旱涝关系形成机制和变化原因。  相似文献   

我国西北夏季降水异常与太平洋海温季节演变的关系   总被引：4，自引：0，他引：4  

唐佑民 《地理学报》1992,47(5):419-429

本文利用交叉相关场的EOF分解考查了我国西北夏季降水与太平洋季节海温遥相关的结构。然后分别就我国西北夏季降水偏多年与偏少年对应的各季海温进行了自然正交（EOF）和复自然正交（CEOF）的合成分析,得到了我国西北夏季降水多、寡年对太平洋海温空间分布异常特征的季节演变。最后利用非参数跃变检验诊断了我国西北降水的跃变,并讨论了与太平洋海温跃变的联系。  相似文献   

THE EFFECTS OF SEA SURFACE TEMPERATURE ANOMALIES OVER THE MID-LATITUDE WESTERN PACIFIC ON THE ASIAN SUMMER MONSOON     

Ni Yunqi  Qian Yongfu 《Acta Meteorologica Sinica》1991,5(1):28-39

By Using the P-σ five-layer primitive equation model,three sets of numerical experiments are performedwith normal zonal mean SST(the control case),the positive SST anomalies in the Kuroshio current andeast-of-Japan Ocean(the midlatitude western Pacific),and positive SST anomalies over both the midlatitudeand the equatorial western Pacific.The experimental results show that the positive SST anomalies over themidlatitude western Pacific have great influence on the Asian summer monsoon:the Indian monsoon is weak-ened and the East Asian monsoon is intensified.This happens just reverse to the effects of positive SSTanomalies over the equatorial westero Pacific on the Asian summer monsoon.Further,the influence mechanismof the SST anomalies over the midlatitude westcrn Pacific on the Asian summer monsoon is discussed.  相似文献   

POTENTIAL VORTICITY STRUCTURE OF SUMMER CYCLONES OVER THE CHANGJIANG-HUAIHE VALLEY     

侯定臣 《Acta Meteorologica Sinica》1991,(1)

Based on the theory of Ertel potential vorticity,the isentropic potential vorticity maps and vertical pro-files of potential vorticity for two summer cyclones over the Changjiang-Huaihe Valley are analysed.Afterdiscussing a possible mechanism for the genesis and development of such systems and their differences fromtypical extratropical cyclones,a conceptual model for their activities is proposed:A weak disturbance in the mid-level of troposphere originated from around the Qinghai-Xizang Plateau may cause heavy precipitation underfavourable conditions and latent heat release in the mid-troposphere leads to downward extension of cycloniccirculation and a wave on the quasi-stationary front.This weak cyclone can develop substantially and becomea typical extratropical cyclone only when air from the lower stratosphere flows downslope along isentropic sur-faces into the region of interest.  相似文献   

THE RELATIONSHIP BETWEEN TROPICAL PACIFIC SEA SURFACE TEMPERATURE AND SUMMER RAINFALL OVER NORTHWEST CHINA   总被引：4，自引：0，他引：4       下载免费PDF全文

Zhu Bingyuan  Li Dongliang 《Acta Meteorologica Sinica》1992,6(4):470-478

In this paper,the data of summer precipitation in Northwest China were expanded by means of EOF.According tomajor eigenvectors in expansion the area of Northwest China was divided into four natural rainfall regions.Amongthem the region of greatest precipitation variability is found over the East Qinghai-North Shaanxi region,includingEast Qinghai,Central and East Gansu,Ningxia and North Shaanxi.There is apparent teleconnection between the firstand second time-dependent coefficients in EOF expansion and the tropical Pacific SST in the corresponding period andearlier months.The variation of the east tropical Pacific SST in winter and spring is able to predict precipitation trend ofNorthwest China next summer.Moreover,in the El Nino years precipitation trend is opposite to the following year,andthe region from East Qinghai to North Shaanxi is most sensitive.  相似文献   

东亚夏季风水汽输送带及其对中国大暴雨与洪涝灾害的影响   总被引：12，自引：1，他引：12       下载免费PDF全文

丁一汇  柳艳菊  宋亚芳 《水科学进展》1990,31(5):629-643

东亚夏季风每年给中国东部地区带来充沛的降水，是中国水资源的主要来源，同时也常常给中国造成严重的洪涝灾害。东亚夏季风水汽输送的强度、影响范围和持续性在极端暴雨过程中起着关键的作用。这支夏季风气流的水汽输送带可称为东亚季风水汽输送带，与国际上近期提出的"大气河"概念相近，但又不完全相同。东亚夏季风水汽输送带是东亚夏季风最具地区性的特征，也是东亚地区夏季大暴雨和洪涝的制造者。本文根据近百年来的资料，综合评述了东亚夏季风水汽输送带的特征和形成原因，并以海河、黄河、淮河与长江近百年最强的5次持续大暴雨过程为例，分析了季风水汽输送带的重要作用。最后，提出气候变暖可以通过4个方面影响全球水循环，包括气候变暖后大气可容纳更多的水汽、大气环流发生变化、辐射强迫改变以及气溶胶影响的区域性等，这些变化都会对季风水汽输送带产生重要影响。  相似文献   

东亚冬季风活动与厄·尼诺的关系   总被引：11，自引：1，他引：11  

郭其蕴  王日昇 《地理学报》1990,(1)

本文利用1951—1986年全球月平均海平面气压资料以及赤道东太平洋的海温资料,研究了东亚冬季风的年际变化与厄·尼诺的关系,主要结果有:(1)东亚冬季风盛行期(10—3)赤道东太平洋海温与海平面气压场的密切相关区,主要位于亚洲南部和西太平洋(正相关)、澳洲北部(正相关)以及阿留申群岛地区(负相关)。(2)海温的变化一般超前冬季风的变化1—2个季节,以11月的海温与之相关最密切。(3)厄·尼诺年冬季,东亚大陆冷空气南下路径偏东,我国南方多雨。反厄·尼诺年相反,冷空气南下路径偏西,我国南方少雨。  相似文献