DECADAL CLIMATE VARIABILITY OF RAINFALL AROUND THE MIDDLE AND LOWER REACHES OF THE YANGTZE RIVER AND ATMOSPHERIC CIRCULATION     

王亚非  高桥清利  荣艳淑 《热带气象学报(英文版)》2005,11(2):169-177

1 INTRODUCTION Summer climate plays an especially important role in the people’s daily life around East Asia, one of the most populated regions in the world, for most of the regions receive more than 70% of the annual precipitation in summer due to the effect of monsoon climate. Global climate change caused by mankind activities have become a hot topic in recent years, though it is still not clear how these activities result in the climate change around East Asia. Successive studies (Qi…  相似文献   

高云与高层垂直速度关系的个例研究II·动力学分析     

王必正  章丽娜 《气候与环境研究》2005,(3)

观测表明,高云的夏季块状分布和冬季带状分布,与低层赤道辐合带的夏季与冬季的形状十分相似;并且卷云和卷层云可以独立于深对流单独存在。作者对这两个观测分析结果进行动力学分析,结论如下:1)由于印度洋北面是青藏高原与亚洲大陆,夏季不能在北面副热带地区形成反气旋,从而印度洋赤道北面为西南气流,导致了赤道辐合带在该地区断裂并且相应的深对流在亚洲季风区的块状分布。2)利用斜压超长波理论,将Rodwell等的亚洲季风单向模型(即非绝热加热导致季风形成)作了修改,扩展为双向闭合模型。印度洋跨赤道偏南风产生大范围水汽辐合,其与地形的共同作用,产生了降水云系的高层加热,由于Sverdrup涡度平衡关系,导致了低层的偏南风而形成了一个相互作用的闭合过程,从而表明了亚洲夏季风是准定常的。3)通过详细分析涡度方程,证明除了恰好在赤道上之外,赤道辐合带上的水平辐合均会产生涡,并且这些涡由点涡(涡度的奇异部分)与各种尺度的涡(涡度的正则部分)组成。正涡度对应于云区,负涡度对应于晴空区,与赤道辐合带(ITCZ)的观测结果一致。4)由于辐合和切变产生涡,得到赤道辐合带和深对流的带状准定常维持的动力机制,即:由于赤道辐合带的辐合,其南北风辐合与东西风切变将产生涡,其与水汽的共同作用产生了深对流的上升降水云系,而降水云系的潜热诱导上升,进一步加强了水平辐合,从而表明了赤道辐合带的带状准定常维持的中介是不同尺度的涡。5)卷云和卷层云可以独立于深对流的原因是热带卷云和卷层云与流场是可以互相激发的,深对流不是其唯一的源。  相似文献   

A Study on the Mesoscale Convective Systems during the Summer Monsoon Onset over the South China Sea in 1998 Part Ⅰ: Analysis of Large-Scale Fields for Occurrence and Development of the Mesoscale Convective Systems          下载免费PDF全文

LIU Yanju DING Yihui ZHAO Nan 《Acta Meteorologica Sinica》2005,19(3):275-288

The summer monsoon onset over the northern South China Sea (SCS) in May 16-20, 1998 was characterized by the abrupt onset of mesoscale convective activities and rapid increase of precipitation. The possible mechanism for formation of the mesoscale convective systems (MCSs) and related rain belts were revealed through discussing their forming physical conditions under the large-scale background: (1) The high pseudo-equivalent potential temperature and the convective instability in the lower troposphere, the low-level southwesterly confluence and the high-level divergence over South China and the northern SCS provided the favorable large-scale thermodynamic and dynamic conditions for development of MCSs. The southwesterly flow from the Bay of Bengal (BOB) interacted with that to the western flank of the subtropical high, which constituted the major moisture channels, thus bringing about deep wet layers and strong moisture convergence;(2) triggered by several cold troughs from high and mid latitudes, the convectively unstable energy was released and the convective activities over the northern SCS broke out abruptly;(3)analysis of retrieved precipitation based on the dual-Doppler radar during South China Sea Monsoon Experiment (SCSMEX) indicated that active convection influenced by the monsoon trough and corresponding wind shear line organized and formed continually some mesoscale convective rainbelts. During May 15-19,about 12 precipitation processes with 6-12-hour life span or more were observed;and (4) under the favorable synoptic conditions, establishment of the monsoon trough and shear line in the low levels, as well as production and development of mesoscale low vortex were all necessary conditions for the formation and maintenance of MCSs.  相似文献   

El Nino演变不同阶段东亚大气环流年际异常型的数值模拟   总被引：4，自引：4，他引：4       下载免费PDF全文

孙旭光  杨修群 《地球物理学报》2005,48(3):501-510

给定1948～1999年逐月变化的全球观测的海表温度分布，使用全球大气环流模式（CCM3/NCAR）模拟了大气对海表温度变化的响应，利用SVD和合成检验方法，分析了El Nino发展阶段夏季、成熟阶段冬季以及衰亡阶段夏季东亚大气环流的年际异常型.结果表明：El Nino发展阶段夏季，中国东北、朝鲜半岛以及日本海附近为高度负异常中心，西太平洋副高偏弱、偏东，东亚夏季风增强；El Nino成熟阶段冬季，东亚大槽加强，东亚北部冬季风加强；El Nino衰亡阶段夏季，西太平洋副高偏强、偏南、西伸，东亚夏季风减弱；El Nino事件在其衰亡阶段夏季与东亚大气环流异常的关系最紧密，其次是成熟阶段冬季，最后是发展阶段夏季.模拟的El Nino演变不同阶段东亚大气环流年际异常型易于解释以往研究中观测分析揭示的由El Nino造成的我国东部气温和降水异常型.  相似文献   

A Study on the Mesoscale Convective Systems during the Summer Monsoon Onset over the South China Sea in 1998Part I: Analysis of Large-Scale Fields for Occurrence and Development of the Mesoscale Convective Systems     

LIU Yanju  DING Yihui  ZHAO Nan 《Acta Meteorologica Sinica》2005,19(3):275-288

1. Introduction China is located in the East Asian monsoon re- gion. Every year's weather and climate in this region is deeply affected by the monsoon activities. Es- pecially, during flooding season (May to September), the summer monsoon controls large-scale precipitation patterns, the movement of seasonal rain belt and oc- currence of drought/flood disasters. The Asian mon- soon can be divided into two systems (Tao and Chen, 1987). As a major component and its unique location, the South …  相似文献   

A Primary Study of Interaction Between Monsoon and Sea Surface Temperature in the Neighborhood Sea Area in South Aisa          下载免费PDF全文

LIU Lihong  ZHENG Zuguang  XIA Youlong  WU Hong 《Acta Meteorologica Sinica》2005,19(3):366-374

1. Introduction South Asian monson is an important weather and climate phenomenon, and it is also an important con- stituent of the global atmospheric circulation, thus people pay more attention to it (Hahn and Manabe, 1975; Zhu and Zhao, 1987; Zhu et al., 1991; Zhou and Yang, 1994; Wu and Huang, 2001; Li et al., 1999). For example, Zhu and Zhao (1987) studied the effects of terrain on South Asian monsoon by the equato- rial atmospheric balance model, indicating that ter- rain effect is …  相似文献   

浅谈湘西南找石英脉型金矿--一种新的找矿方法介绍     

赵代珍  张衡龙  彭思才  李绍维 《华南地质与矿产》2005,(1):72-76

群山具有“金、木、水、火、土”属性，山分阴阳。含金石英脉具三元结构，显金晕景观，属性为金，富金矿体多产于金山和土山中。根据山的属性和山的阴阳，可直接在金山和土山的阳山地段寻找石英脉型金矿。  相似文献   

Marine Boundary-Layer Variability Over The Indian Ocean During Indoex (1998)   总被引：1，自引：1，他引：0  

Vijayakumar Manghnani  Sethu Raman  Devdutta S. Niyogi  Vinayaka Parameswara  John M. Morrison  S. V. Ramana  J. V. S. S. Raju 《Boundary-Layer Meteorology》2000,97(3):411-430

The variability in boundary-layerstructure over the Indian Ocean during a north-eastmonsoon and the factors influencing it areinvestigated. This study was made possible as acomponent of the Indian Ocean Experiment (INDOEX),conducted from February 19 to March 30, 1998. The dataused are, surface-layer mean and turbulencemeasurements of temperature, humidity and wind, andvertical soundings of temperature and humidity.Significant spatio-temporal variability was observedin the boundary-layer structure throughout the cruise.The ITCZ was characterized as the region withstrongest winds and maximum surface turbulent fluxesof momentum and heat. One of the important findingsfrom this study was a strong influence of continentalair masses on the boundary-layer structure in theNorthern Hemisphere, even at a distance of 600 km offthe Indian coast. This was generally evident in theform of an elevated plume of dry continental airbetween altitudes of 1500 m and 2700 m. Advection ofcontinental aerosols in this layer presents potentialfor significant entrainment into shallow clouds inthis region, which eventually feed deeper clouds atthe ITCZ. This finding provides an explanation foranomalous higher aerosol concentrations found duringprevious studies. The structure of the marineboundary layer was influenced by various factors suchas proximity to land, an anomalous warm pool in theocean and the ITCZ. In the southern hemisphere, theboundary-layer height was primarily governed bysurface-layer sensible heat flux and was found to behighest in the vicinity of the ITCZ. North of theequator it was strongly influenced by land-air-seainteractions. In addition to this synoptic modulation,there was also a significant diurnal variability inthe boundary-layer height.  相似文献   

ABRUPT CHANGE IN ELEMENTS AROUND 1998 SCS SUMMER MONSOON ESTABLISHMENT WITH ANALYSIS OF ITS CHARACTERISTIC PROCESS^*          下载免费PDF全文

HE Jinhai  WANG Lijuan  XU Haiming 《Acta Meteorologica Sinica》2000,14(4):426-432

The latest dataset from the SCS(South China Sea) Monsoon Experiment is used to investigate the features of abrupt change in some meteorological elements before,during and after the summer monsoon's establishment in 1998 and explore its onset characteristic process.We have arrived at a preliminary conclusion that the 1998 Asian summer monsoon is established first in the SCS as early as May 23,which is representative of the earliest indicator of the conversion from a winter into a summer monsoon situation in Asia;the continued retreat eastward of the western Pacific subtropical high from the SCS region has direct effect on the SCS summer monsoon establishment because the withdrawal favors the release of unstable energy,responsible for the sudden onset of the monsoon.Our tentative investigation indicates that the eastward extension of the westerly and rainfall band from the equatorial Indian Ocean into the Indo-China Peninsula and the southward spreading of an active South-China stationary front,acting as the interaction between mid and low latitude systems,are likely to be the characteristic events contributing to the subtropical high's eastward retreating and the summer monsoon's onset over the SCS.  相似文献   

THE EFFECT OF LAND-SEA CONTRAST ON INTERANNUAL VARIABILITY OF THE ASIAN MONSOON^*          下载免费PDF全文

LUO Huibang 《Acta Meteorologica Sinica》2000,14(2):200-209

Values of the net radiative heating(QRT)at the top of atmosphere(TOA) are derived from the satellite-observed outgoing long wave radiation(OLR)and the TOA short wave net irradiance (SHT) for the region of the Tibetan Plateau and surrounding areas(40°S-40°N,0-180°E)and the period of months from January 1979 to December 1988.The anomalous QRT(QRTA)in relation to the interannual variability of Asian monsoon is discussed.QRTA for the earth-atmosphere system in the domain may be linked to the thermal contrasts between continents and oceans and between the plateau and surrounding free atmosphere.  相似文献