A COMPARATIVE STUDY OF THE HEATING EFFECTS OF THE TIBETAN PLATEAU AND THE WESTERN PACIFIC*

A zonal domain primitive equation modeling system(ZDMS) is used to study the effects of the initial heating anomalies over the Tibetan Plateau and the western Pacific on the East Asian and the Chinese summer climate,the relative importance and the mechanisms are discussed.Results show that in spite of the different locations of the heating anomalies the influences of the two anomalyareas are much similar to each other when the scaling of the two areas is the same.The two areas of heating anomalies have their own affecting domains in which one is more important than the other.In the western Pacific the heating anomaly over the western Pacific is more evident and in the Tibetan Plateau area the heating anomaly over the Tibetan Plateau is more obvious.For the east part of China the effects of the two heating anomalies both exist and almost have the equal importance.The initial anomaly of the sea surface temperature(SST) over the western Pacific can be kept during the entire time integration while in the Tibetan Plateau it can not be maintained.     

NUMERICAL SIMULATIONS OF HEATING ANOMALY EFFECTS OF TIBETAN PLATEAU ON CIRCULATION IN SUMMER

A 5-layer numerical model with p-σ incorporated coordinate system and primitive equations is used to simulatethe effects of heating anomaly at and over the Tibetan(Qinghai-Xizang)Plateau on the circulations in East Asia in sum-mer,The model is described briefly in the text and the results are analysed in somewhat detail.Results show that the sur-face albedo,the drag coefficient,the evaporation rate and the ground temperature all have large influences on the circula-tion near the Plateau and in East Asia.When the heating at the surface increases,the Tibetan high in the uppertroposphere intensifies,too.Its area enlarges and its axis tilts to northwest.The upper tropical easterly increase andshifts to north.The southwesterly in the lower troposphere,in consistence,also increases.The cross-equatorial low-lev-el currents along Somali and South India are influenced to increase their speeds while those over North Australia de-crease.The land low over the Asian Continent deepens.Meanwhile the upward motions over the land of east China andover the Indo-China Peninsula intensify and therefore the precipitation over those areas increases.However,along thecoastal area of China the upward motions and therefore the precipitation decrease.Atmospheric heat source anomaly has large influence on the circulation,too.Simulated results indicate that heatsource anomaly in the lower atmosphere over the Plateau influences the intensity and the position of the monsoon circu-lation while that in the upper atmosphere only affects the intensity.The heating status over the Plateau has slight influ-ence on the westerly jet,north of the Plateau,while it has strong effect on the subtropical jet at the mid and low latitudes.     

地面热源强迫对青藏高原低涡作用的动力学分析

将一类暖性青藏高原低涡考虑为受加热和摩擦强迫作用并满足热成风平衡的轴对称涡旋系统,给定符合高原地面加热特点的加热分布函数,通过求解简化后的柱坐标系中的涡旋模式,得到了低涡对应的流函数、水平流场、水平散度场和垂直运动场的解析解,分析了地面热源对高原低涡流场结构的作用,给出了高原低涡眼壁内、外侧以及不同高度上的水平流场、水平散度场和垂直流场的结构特征,对影响低涡生成的主要因子进行了讨论。研究结果揭示了地面热源强迫对高原低涡的形成及结构特征的重要作用。     

青藏高原、东亚季风区、西北太平洋地区云系结构及相联加热机制的对比分析

应用7年(2006年5月18日—2013年5月18日)的CloudSat卫星观测资料,对比分析了青藏高原、东亚季风区、西北太平洋地区云发生频率的特征,并利用欧洲中心再分析资料,计算了三个地区的视热源、视水汽汇Q₁、Q₂,分析探讨了三个地区与云发生频率相联系的加热机制。结果表明:青藏高原、东亚季风区、西北太平洋地区云的发生频率分别为35%、22%、27%,其中:青藏高原和东亚季风区的低云频率最大,中云次之;西北太平洋地区的高云和低云的频率大,分别为19%和16%。具体云型来看,青藏高原多高层云、雨层云;东亚季风区多高层云和卷云,夏季深对流云频率增大明显;西北太平洋地区多卷云、深对流云和高层云。三个地区视水汽汇Q₂的垂直分布特征及季节变化与云发生频率对应较好,青藏高原的低云(雨层云)、中云(高层云)形成过程中,凝结释放潜热,加热大气;东亚季风区低云(深对流云)、中云(高层云)对加热大气贡献大;西北太平洋地区大气的主要加热机制是深对流云形成过程中凝结释放潜热以及湿静能涡旋垂直输送。      

青藏高原春夏季对流异常及其对西太平洋副高的影响

高原冬春季净辐射多寡可以显著影响高原地区大气环流季节转换进程和后期高原对流活动。净辐射偏多,初夏高原同低纬度之间温度梯度反转时间提前,高原对活跃,夏季高原主体对流异常,可以通过辐散环流造成西太平洋异常的下沉运动,影响副高的强度、南北位置和西伸程度,最终导致夏季降水的异常分析。     

青藏高原北侧地区干湿年夏季垂直环流差异的对比分析及青藏高原的热力影响

为了分析西北干旱的形成原因，本文首先利用高原北侧地区５站历年夏季的降水量资料等，制定了该区的干湿标准，划分了历年夏季的干湿等级。接着又利用ＥＣＭＷＦ的格点资料等对比分析了该区干湿年夏季间垂直环流的差异，也探讨了青藏高原地面热状况与高原北侧干湿状况的联系。其主要结论是：１）文中制定的以降水标准差为判据的干湿标准适合西北干旱区；２）高原北侧干湿年夏季间在高原北侧和高原上的垂直环流存在明显差异；３）青藏高原地面热状况与上列差异有关，也即青藏高原的热力作用是西北干旱的重要成因之一。     

ON THE RELATIONSHIPS BETWEEN THE SUMMER RAINFALL IN CHINA AND THE ATMOSPHERIC HEAT SOURCES OVER THE EASTERN TIBETAN PLATEAU AND THE WESTERN PACIFIC WARM POOL

The relationships between the summer rainfall in China and the atmospheric heat sources over the eastern Tibetan Plateau and the western Pacific warm pool were analyzed comparatively, using the NCEP/NCAR reanalysis daily data. The strong (weak) heat sou…     

青藏高原感热加热异常与夏季低频环流的数值研究

使用科学院大气物理研究所两层大气环流模式，就青藏高原地表感热通量异常减少对夏季东半球大气环流及亚洲季风低频变化的影响进行了数值试验研究。结果表明：高原地区感热通量异常减少时，南海及西太平洋地区低频振荡方差百分率增大；高原感热异常加热对东亚和印度季风子系统具有不同的影响，季风区低频扰动的位相，中高纬低频扰动的结构，强度和经向传播速度都发生改变，ＥＡＰ波列变得更为清楚典型，大圆上的低频涡旋一直传播到我     

西太平洋副热带高压异常进退的对比分析

对1980年7月29日—8月16日西太平洋副高位置持续偏南和1983年7月16日—8月12日西太平洋副高位置持续偏北的两次季节内副高中期进退过程的环流特征和加热差异作了对比分析,讨论了东亚季风与对流活动、副高进退之间的关系.      

青藏高原东部和西太平洋暖池区大气热源与中国夏季降水的关系

利用1951～2000年NCEP/NCAR逐日再分析资料计算了大气热源,并对夏季青藏高原东部大气热源异常和西太平洋暖池区大气热源异常对中国夏季降水的影响作了对比分析研究.结果表明,如果高原东部夏季大气热源显著偏强(偏弱),则长江流域地区的夏季降水显著偏多(偏少),而华南东部地区夏季降水偏少(偏多).菲律宾南部附近的热带西太平洋暖池区上空夏季大气热源显著偏强(偏弱)时,同期长江中下游地区偏涝(偏旱),而华南地区、江苏北部-山东南部则偏旱(偏涝).夏季青藏高原东部大气热源异常和热带西太平洋暖池区大气热源异常对中国夏季降水的影响是有差别的,中国的夏季降水受高原东部大气热源影响的显著范围要比受西太平洋暖池区大气热源影响的显著范围要大.无论是高原热源异常还是西太平洋暖池热源异常,东亚地区的大气环流都存在类似EAP型的遥相关波列.大气热源的异常是通过直接影响垂直运动场的异常,进而影响到我国的夏季降水的异常.夏季高原热源或西太平洋暖池热源偏强(偏弱)时,西太平洋副高的脊线比常年位置偏南(偏北).     

西太平洋暖池的跃变及其气候效应

用SST（COADS，NCEP）资料研究热带西太平洋暖池的年代际变化和跃变特征，讨论其气候效应。结果表明：西太平洋暖池有显著的10-20年周期的年人际变化和40-50年周期的气候跃变：一百多年来西太平洋暖池发生了4次大跃变，在1910年代中期和1950年代中期，西太平洋暖池由异常发展转为异常减弱，1930年代初和1980年代初，西太平洋暖池由异常减弱转为异常发展：西太平洋暖池在1980年代初的跃变，具明显的效应，跃变后热带中东太平洋海温显著升高，大范围海域升温超过0.5℃，夏季西太平洋副高加强西伸，脊线偏南，我国汛期降水呈南方偏多、北方偏少的分布趋势，与跃变前基本相反。研究结果还表明：在西太平洋暖池异常发展期，El Nino事件出现多且强于La Nina事件，而在西太平洋暖池异常减弱期，La Nina事件出现多且强于El Nino事件。     

THE CLIMATIC JUMP OF THE WESTERN PACIFIC WARM POOL AND ITS CLIMATIC EFFECTS

1INTRODUCTIONTropicalwesternPacificOceanisanareathathasthehighestoceantemperatureacrosstheglobe.Asmostofthewarmwaterconcentratesintheregion,itisknownasthe搘esternPacificwarmpool?Asshowninsomestudies[1-5],thegeneralcirculationandshort-termclimaticchangeswillbeseriouslyaffectedifthermodynamicconditionchangesinthewaters,whichthenhaveanimportantroletoplayintheonsetofanyENSOepisodes.Therehasnotbeenanyunifieddefinitionoftheindexforthewarmpool.FollowingthecriterionofWyrtki[4],however,theareae…     

青藏高原东南部夏季深对流加热研究

文章利用1948～1999年NCEP／NCAR全球深对流加热率再分析资料和1951～2001年全国160站月平均降水量研究了中国区域夏季深对流加热分布状况，青藏高原东南部夏季深对流加热较强，是潜热释放较多和深对流活动旺盛区域；青藏高原东南部深对流加热率与长江中下游地区降水的相关分析也表明，夏季青藏高原东南部深对流活动对长江中下游地区夏季降水偏多有重要影响，可以为长江中下游地区夏季降水提供水分和能量。     

7月青藏高原大气热源空间型及其与东亚大气环流和降水的相关研究

对1958～1999年的7月份NCEP/NCAR再分析资料中青藏高原区域大气热源强度(整层气柱的总非绝热加热率)做旋转经验正交函数分析,结果表明该区域内大气热源强度的空间分布特征复杂,各地差异显著。前4个REOF型的加热中心位于高原东北部、高原西南部、克什米尔地区以及高原东南部地区上空。小波分析还表明各空间型都有2～4a的变化周期。文中计算了前4个RPC与东亚中、低空纬向风(U)、经向风(V)、纬向水汽通量(Q_u)、经向水汽通量(Q_v)的相关系数,并用这些相关系数构造矢量,进而分析其流场和水汽通量散度场,发现高原不同区域的大气加热异常所对应的东亚大气环流形势及降水也大不相同,由此表明,在研究高原加热对中国气候的影响时,应注意加热的空间分布特征。     

EFFECTS OF ANOMALOUS HEATING ON SUMMER MONSOON OVER ASIA

Based on a zonally non-uniform mean circulation in summer simulated by numerical modelling,perturba-tion heatings ever South Asia and a perturbation cooling over Northwest Australia were incorporated in a nu-merical model to discuss their effects on summer monsoon over Asia and the structure of flow disturbance.     

青藏高原热力作用对南海及周边区域夏季气候的影响研究进展

针对青藏高原热力强迫作用对东亚夏季风强度、南海夏季风爆发早晚、南海周边区域旱涝的影响,以及在全球变暖背景下其对降水格局的影响等科学研究进行了总结回顾,并就青藏高原热力作用对南海周边区域夏季气候的影响科学问题进行了探讨。研究表明,高原冬春积雪异常通过影响雪盖反照率、改变辐射平衡和通过积雪-水文效应改变土壤湿度两个途径来影响东亚夏季风;通过改变大陆-海洋经向热力对比影响南海季风爆发早晚;通过改变西太平洋副高位置和季风环流变化来影响华南和长江流域夏季降水的分布。在全球变暖背景下,青藏高原感热加热的减弱可能对降水年代际“南涝北旱”格局的形成具有重要贡献。随着全球变暖减缓,青藏高原中部和东部的感热呈现出复苏态势,“南涝北旱”的降水格局分布在将来有可能被打破。      

A NUMERICAL STUDY ON THE EFFECTS OF THE QINGHAIXIZANG PLATEAU ON THE MEDIUM-RANGE WEATHER PROCESSES OF THE SUMMER MONSOON RAIN IN EAST ASIA

By employing the T42L9 spectral model introduced from ECMWF and utilizing the FGGE-III_b datacovering the period from 14 June to 19 June 1979,the effects of the Qinghai-Xizang Plateau on the medium-range weather processes of the rain during the onset period of the summer monsoon in Eastern Asia in1979 were studied numerically.According to the initial field of 12GMT 14 June 1979,five-day numericalexperiments with or without the orographic effects were carried out respectively.The results show that thePlateau can influence the precipitation significantly during the summer monsoon season.Although the summermonsoon is the result of the seasonal variations of the global circulation and the heating difference betweenland and sea,it is influenced evidently by the Plateau in medium-range processes.There are very complexinteractions between the mountain and diabatic heating effects so that both of them should be consideredcorrectly in the general circulation models in order to describe the nature of the atmosphere reliably.     

CHARACTERISTICS OF ATMOSPHERIC HEATING AND ATMOSPHERIC CIRCULATION DURING ACTIVE PERIOD OF 500 hPa HIGH OVER THE TIBETAN PLATEAU IN SUMMER

In correspondence with the establishment of the“upper high and lower high”pressure pattern due to the activitiesof 500 hPa high over the Tibetan Plateau in summer,a series of changes of the East Asia atmospheric circulation willtake place.In this paper,the distributions of divergence and vertical velocity of 500 hPa high,the evolutions of atmos-pheric heat source,the variations of vorticity and zonal wind at 100 hPa level and vertical meridional cell over theTibetan Plateau etc.are statistically analyzed.Thus,we can see that the ascending motion and the convective heatingover the Tibetan Plateau,the South Asia high and the westerly jet on the north of the Plateau at 100 hPa level are weak-ened.The northern branch and the southern branch of the easterly jet on the south of the Plateau merge into a singlewhole and situate on the south of the former northern branch.In the meantime,thermodynamic land-sea discrepancy inSouth Asia and the convective heating over the Bay of Bengal is enhanced.It will play an important role in the mainte-nance of the easterly jet and the South Asia monsoon.     

青藏高原冬春积雪影响南海季风爆发的数值研究

采用NCAR CAM3.0大气环流模式,研究了冬春季青藏高原积雪异常对南海夏季风爆发的可能影响机制.通过比较多雪年与少雪年试验中的热力场、环流场季节演变的差异得出,多雪年青藏高原感热加热偏弱、高原纬度的中上层大气温度偏低,导致大尺度经向温度梯度反转时间偏晚；同时,青藏高原感热加热偏弱将不利于Hadley环流的季节转换,使得中南半岛上空的下沉异常气流维持时间较长、副高在孟加拉湾断裂的时间偏晚、中南半岛对流爆发偏晚、中南半岛地表温度下降时间偏晚,从而造成中南半岛与南海局地纬向温度梯度反转时间也偏晚.在上述大尺度经向温度梯度以及中南半岛与南海局地纬向温度梯度的共同作用下,多雪年南海季风爆发偏晚.