Some Unique Characteristics of Atmospheric Interannual Variability in Rainfall Time Series over India and the United Kingdom

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Seasonal Transition of Summer Rainy Season over Indochina and Adjacent Monsoon Region

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A Bogus Typhoon Scheme and Its Application to a Movable Nested Mesh Model

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Symmetric Stability of Rotation and Boussinesq Fluid in Bounded Domain by Using Normal Mode Method

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Signatures of a Universal Spectrum for Nonlinear Variability in Daily Columnar Total Ozone Content

ＳｉｇｎａｔｕｒｅｓｏｆａＵｎｉｖｅｒｓａｌＳｐｅｃｔｒｕｍｆｏｒＮｏｎｌｉｎｅａｒＶａｒｉａｂｉｌｉｔｙｉｎＤａｉｌｙＣｏｌｕｍｎａｒＴｏｔａｌＯｚｏｎｅＣｏｎｔｅｎｔＡ．Ｍ．ＳｅｌｖａｍａｎｄＭ．ＲａｄｈａｍａｎｉＳｉｇｎａｔｕｒｅｓｏｆａＵｎｉ...     

A Study on Frontal Motion over Orography

肖庆农，伍荣生ＡＳｔｕｄｙｏｎＦｒｏｎｔａｌＭｏｔｉｏｎｏｖｅｒＯｒｏｇｒａｐｈｙ￥ＸｉａｏＱｉｎｇｎｏｎｓａｎｄＷｕＲｏｎｇｓｈｅｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＡｔｍｏｓｐｈｅｒｉｃＳｃｉｅｎｃｅｓ，ＮａｎｊｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｎａｍｉｎｇ...     

An Introduction to the New Book-GEOSTROPHIC WAVE CIRCULATIONS

ＡｎＩｎｔｒｏｄｕｃｔｉｏｎｔｏｔｈｅＮｅｗＢｏｏｋ－ＧＥＯＳＴＲＯＰＨＩＣＷＡＶＥＣＩＲＣＵＬＡＴＩＯＮＳ￥Ｙｏｎｇ．Ｌ．ＭｃＨａｌｌＤｅｐｔ．ｏｆＥａｒｔｈ，ＡｔｍｏｓｐｈｅｒｉｃａｎｄＰｌａｎｅｔａｒｙＳｃｉｅｎｃｅｓ，ＭＩＴＰｕｂｌｉｓｈｅｄ...     

Some Aspects of the Characteristics of Monsoon Disturbances Using a Combined Barotropic－Baroclinic Model

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Role of Triad Kinetic Energy Interactions for Maintenance of Upper Tropospheric Low Frequency Waves during Summer Monsoon 1988

ＲｏｌｅｏｆＴｒｉａｄＫｉｎｅｔｉｃＥｎｅｒｇｙＩｎｔｅｒａｃｔｉｏｎｓｆｏｒＭａｉｎｔｅｎａｎｃｅｏｆＵｐｐｅｒＴｒｏｐｏｓｐｈｅｒｉｃＬｏｗＦｒｅｑｕｅｎｃｙＷａｖｅｓｄｕｒｉｎｇＳｕｍｍｅｒＭｏｎｓｏｏｎ１９８８Ｄ．Ｒ．Ｃｈａｋｒａｂｏｒｔｙａ...     

Nonlinear Retrieval of Atmospheric Ozone Profile from Solar Backscatter Ultraviolet Measurements:Theory and Simulation

ＮｏｎｌｉｎｅａｒＲｅｔｒｉｅｖａｌｏｆＡｔｍｏｓｐｈｅｒｉｃＯｚｏｎｅＰｒｏｆｉｌｅｆｒｏｍＳｏｌａｒＢａｃｋｓｃａｔｅｒＵｌｔｒａｖｉｏｌｅｔＭｅａｓｕｒｅｍｅｎｔｓ：ＴｈｅｏｒｙａｎｄＳｉｍｕｌａｔｉｏｎ①ＬｉＪｕｎ（李俊）ａｎｄＬｕＤａｒｅｎ...     

Peculiar temporal structure of the south china sea summer monsoon

Beijing located at the junction of four major components of the Asian-Australia monsoon system (the Indian, the western North Pacific, the East Asian subtropical, and the Indonesian-Australian monsoons), the monsoon cli-mate over the South China Sea (SCS) exhibits some unique features. Evidences are presented in this paper to reveal and document the following distinctive features in the temporal structure of the SCS summer monsoon:(1) pronounced monsoon singularities in the lower tropospheric monsoon flows which include the pre-onset and withdrawal easterly surges and the southwesterly monsoon bursts at Julian pentad 34-35 (June 15-24) and pentad 46-47 (August 14-23);(2) four prominent subseasonal cycles (alternative occurrences of climatological active and break monsoons);(3) considerably larger year-to-year variations in convective activity on intraseasonal time scale compared to those over the Bay of Bengal and the Philippine Sea;(4) the redness of the climatological mean spectrum of precipitation / deep convection on synoptic to intraseasona] time scales in the central SCS;(5) a remarkable asymmetry in the seasonal transitions between summer and winter monsoons and an extremely abrupt mid-May transition (the outburst of monsoon rain and the sudden switch in tie lower troposphere winds from an easterly to a westerly regime);(6) the bi-modal interannual variation of summer monsoon onset (normal and delayed modes).In addition, the monsoon rainfall displays enormous east-west gradient over the central SCS. Possible causes for these features are discussed. A number of specific science questions concerning some of the peculiar features are raised for the forthcoming SCS monsoon experiment to address     

THE CLIMATIC CHARACTERISTICS OF SUMMER MONSOON ONSET OVER THE SOUTH CHINA SEA I.40-YEAR AVERAGE

By using 40-year NCEP reanalysis daily data (1958-1997), we have analyzed the climatic characteristics of summer monsoon onset in the South China Sea (105°E ~ 120°E, 5°N ~ 20°N, to be simplified as SCS in the text followed) pentad by pentad (5 days). According to our new definition, in the monsoon area of the SCS two of the following conditions should be satisfied: 1) At 850hPa, the southwest winds should be greater than 2m/s. 2) At 850 hPa, θ_se should be greater than 335°K. The new definition means that the summer monsoon is the southwest winds with high temperature and high moisture. The onset of the SCS summer monsoon is defined to start when one half of the SCS area (105°E ~ 120°E,5°N ~ 20°N) is controlled by the summer monsoon. The analyzed results revealed the following: 1) The summer monsoon in the SCS starts to build up abruptly in the 4th pentad in May. 2) The summer monsoon onset in the SCS is resulted from the development and intensification of southwesterly monsoon in the Bay of Bengal. 3) The onset of the summer monsoon and establishment of the summer monsoon rainfall season in the SCS occur simultaneously. 4) During the summer monsoon onset in the SCS, troughs deepen and widen quickly in the lower troposphere of the India; the subtropical high in the Western Pacific moves eastward off the SCS in the middle troposphere; the easterly advances northward over the SCS in the upper troposphere.     

Analysis of Basic Features of the Onset of the Asian Summer Monsoon

In this paper,a relatively systematic climatological research on the onset of the Asian tropical summer monsoon(ATSM)was carried out.Based on a unified index of the ATSM onset,the advance of the whole ATSM was newly made and then the view that the ATSM firstly breaks out over the tropical eastern Indian Ocean and the middle and southern Indo-China Peninsula was further documented,which was in the 26th pentad(about May 10),then over the South China Sea(SCS)in the 28th pentad.It seems that the ATSM onset over the two regions belongs to the different stages of the same monsoon system.Then,the onset mechanism of ATSM was further investigated by the comprehensive analysis on the land-sea thermodynamic contrast,intraseasonal oscillation,and so on,and the several key factors which influence the ATSM onset were put forward.Based on these results,a possible climatological schematic map that the ATSM firstly breaks out over the tropical eastern Indian Ocean,the Indo-China Peninsula,and the SCS was also presented, namely seasonal evolution of the atmospheric circulation was the background of the monsoon onset;the enhancement and northward advance of the convections,the sensible heating and latent heating over the Indo-China Peninsula and its neighboring areas,the dramatic deepening of the India-Burma trough,and the westerly warm advection over the eastern Tibetan Plateau were the major driving forces of the summer monsoon onset,which made the meridional gradient of the temperature firstly reverse over this region and ascending motion develop.Then the tropical monsoon and precipitation rapidly developed and enhanced. The phase-lock of the 30-60-day and 10-20-day low frequency oscillations originated from different sources was another triggering factor for the summer monsoon onset.It was just the common effect of these factors that induced the ATSM earliest onset over this region.     

亚洲夏季风爆发的深对流特征

文中应用ＮＯＡＡ卫星反演的１９８０～１９９５年候平均对流层上部水汽亮温（ＢＴ）资料、向外长波辐 射（ＯＬＲ）资料和美国ＮＭＣ全球分析８５０　ｈＰａ风资料与美国ＣＭＡＰ降水资料作了对比分析，发现Ｂ Ｔ能够较好地反映中低纬度地区的深对流降水，偏南风场辐合区与深对流降水有比较一致的 关系，而ＯＬＲ不能反映热带外地区的对流降水。ＢＴ资料所具有的这一特征可以应用于亚洲夏 季风爆发过程的深对流特征分析。ＢＴ描述深对流的临界值是２４４　Ｋ。亚洲季风区是全球深对 流季节变化范围和强度最大的地区。赤道外地区的夏季风爆发可以定义为来自热带地区深对 流的季节扩张。中南半岛上的夏季风对流发生在南海夏季风爆发之前。华南前汛期深对流是 中低纬系统相互作用的结果。第２８候，南海夏季风的突然爆发在降水、风场和卫星反演 的深对流特征上都有明确的反映。南海夏季风爆发后，印度夏季风对流由南向北逐渐爆发， 青藏高原东侧和中国东部沿海的夏季风对流向北推进早于中国中部地区。     

2011年南海夏季风爆发过程及其与长江中下游梅雨的联系

采用NCEP/NCAR再分析资料、FY2E-TBB及台站降水资料,对2011年南海夏季风爆发前后的环流特征进行分析。结果表明:2011年强对流活动由孟加拉湾扩展到南海地区,同时伴随着南亚高压移至中南半岛北部,西太平洋副热带高压向东撤出南海地区,南海夏季风于5月第4候(第28候)爆发;季风爆发后,印度-孟加拉湾季风槽形成,南海地区低空开始盛行西南气流,并伴有对流降水的发展和温、湿等要素的突变。随着季风活动的推进,我国雨带北抬,长江中下游一带进入梅雨期,出现降水大值区。通过分析发现长江中下游梅雨与南海夏季风均受副热带高压影响,且两者的强度为显著的负相关关系,梅雨开始时间与南海夏季风爆发时间呈显著的正相关关系。2011年南海夏季风偏弱,爆发时间偏早,长江中下游梅雨强度偏强,入梅时间异常偏早。     

亚洲季风季节进程的若干认识

简要归纳了不同时期随着观测资料的更新对亚洲季风季节进程的若干认识。南海季风试验前,研究认识了东亚季风系统与南亚季风系统的区别。南海季风试验后,对季风进程有了更多的认识,江南副热带雨季开始于4月初,中印半岛热带雨季开始于4月底,南海热带雨季突然建立于5月中旬,都具有半年际的干湿转换。南海中部季风爆发后,亚洲季风在南亚、青藏高原东侧和东亚-太平洋地区全面爆发并由南向北推进。利用近年来高分辨率资料并考虑热带地区半岛陆海地形与热力的影响,认识到亚洲存在5个夏季季风槽与降水相联系的系统,它们分别是西南亚(阿拉伯海)夏季热带季风、南亚(孟加拉湾)夏季热带季风、东南亚(南海)夏季热带季风、西北太平洋夏季热带季风和东亚夏季副热带季风。     

南海夏季风演变的气候学特征

本文总结南海北部地区夏季风演变的气候学特征，发现南海地区５月第３候对流层高层东风和北风爆发，对流层低层西风第１次跃升，东亚经向季风环流圈开始形成，这可以成为南海地区夏季风爆发的标志。对流层低层西风在６月中旬开始的第２次连续跃升对应江淮地区的梅雨爆发期。类似地，中国大陆夏季对流层低层５月初和６月初有两次爆发性增暖过程，第２次比第１次强烈得多。南海北部地区对流层低层纬向风速、比湿盛夏呈双峰型，纬向风速峰值分别出现在６月第５候和８月第４候，比湿峰值分别出现在６月第６候和８月第５候。比湿突升对应纬向风速突升，但略落后于风速峰值出现的时间。南海北部地区季风爆发前，温度是波动式上升的，南海季风爆发后，温度是波动式下降的。中国大陆东部及南海地区夏季对流层低层比湿分布有３次突变，即４月中旬南海北部比湿突增，并开始出现高比湿中心，而南海南部为最大比湿中心；５月中旬最大比湿中心已从南海南部跳到了南海北部－华南并向江淮流域扩展；６月中旬江淮流域比湿突增并一直维持到８月，同时南海南部高比湿带消失。而５月中旬ＯＬＲ有一次突变，ＯＬＲ低值区爆发性向北扩张，这对应于南海地区夏季风的爆发。而孟加拉湾地区夏季风演变的气候学特征与南海地区有较     

CLIMATIC CHARACTERISTICS OF THE ONSET OF SOUTH CHINA SEA SUMMER MONSOON II. INTER-DECADAL VARIATION

By using the 40-year NCEP (1958-1997) grid point reanalysis meteorological data, we analyzed the inter-decadal variation on the climatic characteristics of the onset of South China Sea summer monsoon. The results are as follows. (1) There was great difference on the onset date of the SCS summer monsoon between the first two decades and the last two decades. It was late on the 6th pentad of May for the first two decades and was on the 4th and 5th pentad of May for the next two decades. (2) Except for the third decade (1978-1987), the establishment of the monsoon rainfall was one to two pentads earlier than the onset of the summer monsoon in all other three decades. (3) The onset of the SCS monsoon is the result of the abrupt development and eastward advancement of the southwesterly monsoon over the Bay of Bengal. The four-decade analysis shows that there were abrupt development of the southwesterly monsoon over the Bay of Bengal between the 3rd and 4th pentad of May, but there was great difference between its eastward movement and its onset intensity. These may have important effect to the earlier or later onset of the SCS summer monsoon. (4) During the onset of the SCS summer monsoon, there were great difference in the upper and lower circulation feature between the first two and the next two decades. At the lower troposphere of the first two decades, the Indian-Burma trough was stronger and the center of the subtropical high was located more eastward. At the upper troposphere, the northward movement of the center of subtropical high was large and located more northward after it landed on the Indo-China Peninsula. After comparison, we can see that the circulation feature of the last two decades was favorable to the establishment and development of the SCS summer monsoon.     

Multi-scale climate variability of the South China Sea monsoon: A review

This review recapitulates climate variations of the South China Sea (SCS) monsoon and our current understanding of the important physical processes responsible for the SCS summer monsoon's intraseasonal to interannual variations. We demonstrate that the 850 hPa meridional shear vorticity index (SCSMI) can conveniently measure and monitor SCS monsoon variations on a timescale ranging from intraseasonal to interdecadal. Analyses with this multi-scale index reveal that the two principal modes of intraseasonal variation, the quasi-biweekly and 30–60-day modes, have different source regions and lifecycles, and both may be potentially predicted at a lead time longer than one-half of their corresponding lifecycles. The leading mode of interannual variation is seasonally dependent: the seasonal precipitation anomaly suddenly reverses the sign from summer to fall, and the reversed anomaly then persists through the next summer. Since the late 1970s, the relationship between the SCS summer monsoon and El Niño-Southern Oscillation (ENSO) has significantly strengthened. Before the late 1970s, the SCS summer monsoon was primarily influenced by ENSO development, while after the late 1970s, it has been affected mainly in the decaying phase of ENSO. The year of 1993 marked a sudden interdecadal change in precipitation and circulation in the SCS and its surrounding region. Over the past 60 years, the SCS summer monsoon's strength shows no significant trend, but the SCS winter monsoon displays a significant strengthening tendency (mainly in its easterly component and its total wind speed). A number of outstanding issues are raised for future studies.     

CLIMATIC CHARACTERISTICS OF THE ONSET OF SOUTH CHINA SEASUMMER MONSOONⅡ.INTER—DECADAL VARIATION

By using the 40-year NCEP(1958-1997) grid point reanalysis meteorological data.we analyzed the inter-decadal variation on the climatic characteristics of the onset of South China Sea summer monsoon.The results are as follows.(1) There was great difference on the onset date of the SCS summer monsoon between the first two decades and the last two decades,It was late on the 6^th pentad of May for the first two decades and was on the 4^th and 5^th pentad of May for the next two decades.(2)Except for the third decade(1978-1987),the establishment of the monsoon rainfall was one to two pentads earlier than the onset of the summer monsoon in all other three decades.(3) The onset of the SCS monsoon is the result of the abrupt development and eastward advancement of the southwesterly monsoon over the Bay of Bengal.The four-decade analysis shows that there were abrupt development of the southwesterly monsoon over the Bay of Bengal between the 3rd and 4th pentad of May,but there was great difference between its ewastward ovement and its onset intensity.These may have important effect to the earlier or later onset of the SCS summer monsoon.(4) During the onset of the SCS summer monsoon.there were great difference in the upper and lower circulation feature between the first two and the next two decades.At the lower troposphere of the first two decades.The Indian-Burma trough was stronger and the center of the subtropical high was located more eastward.At the upper troposphere.the northward movement of the center of subtropical high was large and located more northward after it landed on the lndo-China Peninsula.After comparison.we can see that the circulation feature of the last two decades was favorable to the establishment and development of the SCS summer monsoon.