Relationship between the atmospheric heat source over Tibetan Plateau and the heat source and general circulation over East Asia

On the basis of NCEP/NCAR version I daily reanalysis data from 1971 to 2000 and by the methods of inverse calculation, correlation analysis and comparative analysis, the influences of atmospheric heat source （AHS） over the Tibetan Plateau on the large-scale AHS and the general circulation in summer are studied in this paper. The results show that AHS over the plateau in summer may trigger a heat source wavetrain propagating northeastward along the coast from the East Asian continent and West Pacific to Bering Strait-Arctic or even North America. In addition, if AHS over the eastern plateau is intense, South Asian High moves to southeast and West Pacific subtropical high moves to southwest; on the contrary, if AHS over the eastern plateau is weak, South Asian High moves to northwest and West Pacific subtropical high moves to northeast. Therefore, South Asian High and West Pacific subtropical high move in the horizontally-opposite directions in terms of interannual variation, for which AHS over the eastern plateau seems to be thermodynamically responsible.     

冬春海温异常对东亚初夏季风环流的影响

用ＯＳＵ的两层大气环流模式进行了热带西太平洋冬春海温异常对东亚初夏（５月）季风环流影响的数值试验．结果表明：①海温的负距平引起西太平洋副热带高压脊南落和西伸，东亚热带季风环流减弱，我国西南和华南地区的降水增加；②海温的正距平引起西太平洋副热带高压明显减弱，西太平洋的赤道西风加强，我国西南和华南地区的降水减少     

Southern Hemisphere mean zonal wind in upper troposphere and East Asian summer monsoon circulation

1 Introduction Variability of the East Asian summer monsoon (EASM) has been detected by considering roles of El Nino and Southern Oscillation (ENSO) cycle, snow cover over Eurasia and Tibetan Plateau, and signals from the soil (namely, the soil temperatur…     

Features of the EAP events on the medium-range evolution process and the mid- and high-latitude Rossby wave activities during the Meiyu period

In this paper, features for the evolution of the East Asia/Pacific （EAP） events and their association with high- and mid-latitude Rossby waves during the Meiyu period are analyzed on the medium-range time scale, it is shown that life cycles of the positive and negative EAP events cannot be simply regarded as ＂mirror＂ each other. In the upper troposphere, downward propagations of Rossby wave packets both over high- and mid-latitude regions of Eurasian continent and over the Asian jet region are responsible for generating basic patterns of high- and mid-latitude anomaly centers of the events. In this layer, Rossby wave packets also propagate from the mid-latitude anomaly center to the high-latitude one. In the middle and lower troposphere, the formation of the subtropical anomaly center of the event is mainly attributed to the anomalous convective activity in the tropical Pacific warm pool. The northward Rossby wave energy dispersion from this center is favorable to the enhancement and maintenance of the mid-latitude anomaly center in the same layer. Finally, it might be hypothesized that typical features of the positive and negative EAP events in their mature phase result from the interaction between （or phase-locking of） respective anomalous circulations induced both by quasi-zonal Rossby wave packets embedded in upper troposphere westerly and by quasi-meridional Rossby wave packets in the background flow of the East Asian summer monsoon in the middle and lower troposphere.     

中国西部绿化对东亚季风气候影响的数值模拟

中国西部大开发战略中的生态环境建设将在西部地区引起显著的地表覆盖变化。根据最新的全球地表特征数据库资料和21世纪初中国西部生态环境三大重点建设工程的具体规划，得出两种植被，即现实植被和虚拟植被。并利用RIEMS—TEA模式，通过一次敏感性试验，发现西部地区绿化明显影响东亚的季风系统和中国东部季风区气候。模拟试验显示，中国西部绿化会明显增强东亚夏季风，这将会加强中国东部由南向北的水汽输送，并有利于输送邻近海洋的水汽到大陆，使得中国大陆东部季风区整体出现降温、增湿和降水增加。而且，温度、湿度、气压和风速受影响的程度在垂直方向上都已超出了边界层之外。     

East Asian monsoon change for the 21st century: Results of CMIP3 and CMIP5 models

Forty-two climate models participating in the Coupled Model Intercomparison Project Phases 3 and 5 were first evaluated in terms of their ability to simulate the present climatology of the East Asian winter (December-February) and summer (June-August) monsoons. The East Asian winter and summer monsoon changes over the 21st century were then projected using the results of 31 and 29 reliable climate models under the Special Report on Emissions Scenarios (SRES) mid-range A1B scenario or the Representative Concentration Pathways (RCP) mid-low-range RCP4.5 scenario, respectively. Results showed that the East Asian winter monsoon changes little over time as a whole relative to the reference period 1980-1999. Regionally, it weakens (strengthens) north (south) of about 25°N in East Asia, which results from atmospheric circulation changes over the western North Pacific and Northeast Asia owing to the weakening and northward shift of the Aleutian Low, and from decreased north- west-southeast thermal and sea level pressure differences across Northeast Asia. In summer, monsoon strengthens slightly in East China over the 21st century as a consequence of an increased land-sea thermal contrast between the East Asian continent and the adjacent western North Pacific and South China Sea.     

华北地区1972年和1997年干旱特征及其影响系统分析

利用华北地区实测的月降水量资料,美国NCAR/NCEP 850 hPa的矢量风5、00 hPa和850 hPa的位势高度等再分析资料,分析了华北地区1972年和1997年这2个干旱年干旱的空间分布、强度分布和持续时间,以及西太平洋副热带高压变化、季风进退和欧亚大气环流异常情况.结果表明:1972年是季风正常年,但该年亚洲大陆高压偏强且持续存在、西太平洋副热带高压持续偏弱,导致了干旱的发生与持续;而1997年由于持续偏强的亚洲大陆高压、持续偏弱的季风和西太平洋副热带高压造成该地区严重干旱.     

Inverse correlation between ancient winter and summer monsoons in East Asia？

There is a scientific debate on the relationship between ancient winter and summer monsoons in East Asia. Some scholars think that East Asian winter and summer monsoons are anti-correlated, and others think not. For this reason, this study is motivated to assess their linkage from the paleoclimate simulation perspective, through analyzing the Last Glacial Maximum （LGM） and mid-Holocene （MH） climate simulated by CCSM3 model. Compared to the present climate, the Aleutian low is found to be deepened and the East Asian winter monsoon （EAWM） is stronger during the LGM winter. The Pacific high in summer is noticed to be weakened and the East Asian summer monsoon （EASM） is weaker at the LGM. During the MH, the Aleutian low and the Asian high in winter are intensified, and the Asian low and the Pacific high in summer are enhanced, indicating that the EAWM and EASM are both stronger than today. Therefore, the EAWM is not always negatively correlated to the EASM. Their relationship may be different at different geological stages. It can be obtained at least from the numerical simulation results that the EAWM and the EASM is negatively correlated during the cooling period, while positively correlated during the warming period.     

2003年东亚夏季风活动的特点

利用2003年国家气象中心提供的再分析资料以及台站降水资料，诊断分析了2003我国东部地区汛期降水和东亚夏季风的活动特点，并对二者之间的联系进行讨论。结果表明：(1)2003年南海夏季风于5月第5候在南海南部建立。6月第1候全面爆发，比常年偏晚，南海夏季风强度也比常年偏弱；(2)该年夏季，副热带高压的一个显著特点是强度强、位置偏西，其中从6月下旬至7月中旬，副热带高压的位置稳定少变，其北脊线位25oN附近，且副高位置偏西，这导致了长江以南的犬部分地区高温少雨。这个阶段副热带高压西侧的南风气流将南海地区的水汽源源不断地输送到淮河流域，是淮河流域强降水过程水汽主要来源。     

亚欧大陆经向热力差异对亚洲季风的影响Ⅰ:与东亚冬季风的关系

 通过对亚欧大陆不同季节热力变化的对比分析,发现亚欧大陆冬、春季有明显的经向热力差异,夏、秋季存在准纬向的热力差异.进一步分析还发现大陆冬季经向热力差异与东亚冬季风有很好的正相关关系,即热力差异指数越大(小),则东亚冬季风越强(弱);在经向热力异常发生的同时,洋面热力状况也显著不同,从而导致东亚地区不同区域间海陆热力对比发生变化,引起降水分布的不同.     

华北夏季降水年代际变化与东亚夏季风、大气环流异常

利用华北夏季降水资料和NCEP/NCAR再分析资料,对华北夏季降水、东亚夏季风年代际变化特征及大气环流异常进行研究,发现一些有意义的结果:华北夏季降水变化存在明显的8a、18a周期,东亚夏季风变化18a、28a周期性比较明显,二者年代际变化特征明显,但华北夏季降水变化和东亚夏季风变化的周期不完全一致.华北夏季降水量变化在60年代中期发生了突变,东亚夏季风变化在70年代中期发生了突变.华北夏季降水与东亚夏季风变化存在很好的相关关系,强夏季风年,华北夏季降水一般偏多,弱夏季风年,华北夏季降水一般偏少,但又不完全一致.东亚夏季风减弱是造成华北夏季降水减少的一个重要因素,但不是唯一因素,华北夏季降水减少还与环流异常密切相关.在地面上,青臧高原地区、华北地区气温下降造成华北低压系统活动减少,不利于降水.在850 hPa层上,东亚中纬度的西南季风和副热带高压南部的偏东风、西北部的西南风异常减弱,使得西南气流输送水汽很多难以到达30°N以北的地区,而副热带高压西部外围偏东南、偏南气流输送到华北地区的水汽也大量减少,水汽不足造成华北夏季降水偏少.在500 hPa高度场上,80年代欧亚遥相关型表现与50年代相反,变为欧洲( )、乌拉尔山(-)、中亚( )形势,这种环流使得乌拉尔山高压脊减弱,贝加尔湖至青藏高原高空槽变浅,纬向环流表现突出,不利于冷暖空气南北交换.同时在500 hPa气温场上,80年代,西伯利亚至青藏高原西北部的冷槽明显东移南压到蒙古至华北地区,锋区位于华北以东以南位置,使得华北地区冷暖空气交汇减少,降水也因此减少.华北夏季降水减少是由于东亚夏季风减弱和大气环流异常造成的.     

Evolution of the East Asian monsoon and its response to uplift of the Tibetan Plateau since 1.8 Ma recorded by major elements in sediments of the South China Sea

Evolution of the East Asian monsoon and its response to uplift of the Tibetan Plateau has been investigated in the study of global change. Core sediment samples drilled in the South China Sea during ODP Leg184 are the best materials for studying long-term variability of the East Asian monsoon. R-mode factor analysis of major elements in the fine grain-sized carbonate-free sediments (<4 μm) of the upper 185 mcd splice of ODP Site 1146 drilled during Leg184 in the South China Sea shows that Ti, TFe2O3, MgO, K2O, P, CaO, and Al2O3 are representative of a terrestrial factor. The variation in the terrestrial factor score is subject to chemical erosion in the source region and thus indicates the evolution of the East Asian summer monsoon. The terrestrial factor score has three stepwise decreases at ~1.3 Ma, ~0.9 Ma, and ~0.6 Ma, indicating the phased weakening of the East Asian summer monsoon is related to wholly stepwise, quick uplifts of the Tibetan Plateau since 1.8 Ma. The periodic fluctuation of the terrestrial factor score since ~0.6 Ma indicates that the glacial-interglacial cycles have been the main force driving the evolution of the East Asian monsoon. As in the case of Chinese loess, the long-term evolution of the East Asian monsoon recorded in sediments of the South China Sea reflects a coupled effect of the glacial-interglacial cycle and uplift of the Tibetan Plateau.     

青藏高原对亚洲季风平均环流影响的数值试验

利用垂直方向具有９层σ面、水平方向菱形截断波数为１５的全球大气环流谱模式和有、无青藏高原大地形两种情况下１０年积分的模拟结果，研究了青藏高原大地形对亚洲季风平均环流的影响。结果表明：有、无青藏高原大地形，亚洲冬、夏季季风平均环流均存在很大的差异。去除地形，使夏季高层的南亚高压、低层的大陆热低压、副热带高压及冬季的大陆冷高压在位置或强度上发生了改变；地形的有、无决定着冬季东亚大槽的强度；索马里越赤道气流有地形时明显较无地形时强；地形的有无还影响着降水强度和雨带的分布。另外，副热带高压中心及雨带的季节性移动与高原大地形的存在与否亦有很大的关系     

Study on response of ecosystem to the East Asian monsoon in eastern China using LAI data derived from remote sensing information

Based on the leaf area index (LAI) data derived from remote sensing information and eco-climate data, the responses of regional ecosystem variations in seasonal and interannual scales to the East Asian monsoon are studied. It is found that the vegetation ecosystems of eastern China are remarkably correlated with the East Asian monsoon in seasonal and interannual scales. In the seasonal timescale, the obvious variations of the vegetation ecosystems occur with the development of the East Asian monsoon from the south in the spring to the north in the autumn. In the interannual scale, high LAI appears in the strong East Asian monsoon year, whereas low LAI is related to the weak East Asian monsoon year. These further lead to the characteristic of "monsoon-driven ecosystem" in the eastern China monsoon region, which can be revealed by LAI.     

ENSO对东亚夏季风和我国夏季降水的影响研究进展

回顾了最近几年我国学者在ENSO对东亚夏季风和我国夏季降水影响方面的研究成果,通过夏季风时降水的影响分析ENSO对夏季降水的作用,结合1997-1998年的ENSO现象,对前人的理论和统计结果进行了讨论,指出除了ENSO发生的时间、区域、强度外,其增长和衰减率在这一问题的研究中也值得关注。     

Interconnections between the Asian monsoon, ENSO, and high northern latitude climate during the Holocene

The International Geosphere Biosphere Program (IGBP), which promotes better understanding of the living environment, was initiated in the early 1990s. IGBP and other programs have uncovered much evi-dence that the Earth system is complex and nonlinear, ex…     

东亚夏季风异常的研究

本文运用经验正交函数分析方法,对10～65°N,90°E～175°W范围内近30年逐年7月和8月平均海平面气压场进行了分析研究.结果表明,第一、第三特征向量与东亚季风异常有关,第二特征向量与西风环流异常有关.讨论了东亚季风异常与大气环流的关系,以及季风异常对华北东部地区降水时空分布的影响.     

Relationship between the simulated East Asian westerly jet biases and seasonal evolution of rainbelt over eastern China

Due to the particular geographical location and topog- raphical features, the East Asia exhibits prominent mon- soonal climate with significant seasonal variation and complex spatial distribution of climatic elements. There are many difficulties in simulating and forecasting the weather and climate over East Asia by using climate model system. Generally speaking, the capability and performance of the currently widely-used climate modelsin East Asia are not satisfied. It is of scientific sign…     

南海夏季风活动激发的大气遥相关型

北半球夏季,南海地区是全球大气热状况变化最为激烈的区域之一,而南海夏季风则是该地区最为活跃的天气事件,它的演变必将导致其它地区大气环流的响应．通过相关计算、合成分析等手段,揭示与南海夏季风活动相关联的北半球大气遥相关型的存在．该波列状的遥相关型与东亚地区相连,经北太平洋延伸至北美西岸．最高的相关位于西太平洋副热带高压区域,因而它可能对我国旱涝天气产生重要影响．     

Identifying the northernmost summer monsoon location in East Asia

An integrated index which can be used to indicate the advance of subtropical summer monsoon in East Asia has been proposed in this paper.The index was comhined by three variables including precipitation,wind and pseudo-equivalent potential tempera- ture.The northernmost summer monsoon location(NSML)was identified by using this index annually.It was found that the NSML ex- perienced an interdecadal shift in the period 1977—1979 based on the annual index analysis from 1961 to 2001.A comparison of the NSML with other four summer monsoon indices has also been made.The result showed that the NSML could well represent the interan- nual and interdecadal variability of summer monsoon precipitation in North China(beyond 35°N),while other four indices could well indi- cate the precipitation anomalies of East Asian summer monsoon along the Yangtze River valley(around 30°N).