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From a statistical study of the atmospheric circulation types over the Northern Hemisphere it is found that the zonal type circulation predominates in East Asia. From a three-layer primitive equation model in σ-coordinate, the orographic effect on a westerly current over the Northern Hemisphere is studied. A distinguished deepening trough is observed in the lee-side slope of the Rocky Mountains. But a pronounced trough is over the East Asia coast far from the Tibetan Plateau. In a case of 48 h numerical forecast, it is found that the effect of the Tibetan Plateau tends to build up a rather zonal type circulation, which is con-sistent with the observations. These may be partly explained by the topographic effect of the north slope of the Tibetan Plateau in a simple geostrophic theory. 相似文献
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2018年7月北半球天气气候显著异常,极端事件高发。欧洲、北非、东亚以及北美的大部分地区均遭受严重的高温热浪侵袭;印度、东南亚、中国西南部以及日本西部等地出现极端降水;西太平洋台风活动异常活跃,移动路径偏北。初步诊断表明,北半球中高纬度,由低层到高层稳定维持的异常高压系统是导致北半球中高纬度大部分地区高温热浪持续发生的直接原因。其中异常偏强、偏北的副热带高压,以及增强、东伸的南亚高压与东亚地区持续高温和极端降水事件直接相关;低层菲律宾周围异常活跃的对流活动和强盛的西南水汽输送共同导致南亚、东南亚地区极端降水发生。热带太平洋大部分地区偏暖的海温条件和菲律宾附近异常气旋性环流则与异常活跃的台风活动有关。更需要关注的是,北半球尤其是东亚地区大气环流的异常主要受海洋表面热力状况以及其他区域大气环流遥相关的影响。 相似文献
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In this paper, the anomaly of disturbance height field over Northern Hemisphere due to SST anomaly in the tropical Atlantic
Ocean is simulated by using the general circulation model of IAP. A quasi-geostrophic, 34-level spherical coordinate model
is also used to compute the distribution of atmospheric circulation anomaly when there is an anomaly of heat source over the
tropical Atlantic. The computed results show that, owing to the heat source anomaly over the tropical Atlantic, the EU-pattern
anomaly in the winter circulation may be caused. Namely, a ridge will be enhanced over the northwest Europe, a trough will
be deepened over Siberia, but a positive anomaly of disturbance height field will be formed over the northeast China, Japan
and other areas of East Asia. Moreover, the numerically simulated results show that the above-mentioned EU-pattern anomalies
of circulation are due to the propagations of planetary wave train. About 15 days after an anomaly of the heat source over
the tropical Atlantic is injected, the EU-pattern anomaly of atmospheric circulation is formed. This is in good agreement
with the results analysed theoretically.
On the leave from Geophysical Institute, Faculty of Science in Tokyo University, Japan. 相似文献
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NUMERICAL SIMULATION OF EURASIAN TELECONNECTION PATTERN IN ATMOSPHERIC CIRCULATION DURING THE NORTHERN HEMISPHERE WINTER 总被引：5，自引：0，他引：5
In this paper, the anomaly of disturbance height field over Northern Hemisphere due to SST anomaly in the tropical Atlantic Ocean is simulated by using the general circulation model of 1AP. A quasi-geostrophic, 34-level spherical coordinate model is also used to compute the distribution of atmospheric circulation anomaly when there is an anomaly of heat source over the tropical Atlantic. The computed results show that, owing to the heat source anomaly over the tropical Atlantic, the EU-pattern anomaly in the winter circulation may be caused. Namely, a ridge will be enhanced over the northwest Europe, a trough will be deepened over Siberia, but a positive anomaly of disturbance height field will be formed over the northeast China, Japan and other areas of East Asia. Moreover, the numerically simulated results show that the above-mentioned EU-pattern anomalies of circulation are due to the propagations of planetary wave train. About 15 days after an anomaly of the heat source over the tropical Atlantic is 相似文献
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南极海冰首要模态呈现偶极子型异常,正负异常中心分别位于别林斯高晋海/阿蒙森海和威德尔海。过去研究表明冬春季节南极海冰涛动异常对后期南极涛动（Antarctic Oscillation,AAO）型大气环流有显著影响,而AAO可以通过经向遥相关等机制影响北半球大气环流和东亚气候。本文中我们利用观测分析发现南极海冰涛动从5～7月（May–July,MJJ）到8～10月（August–October, ASO）有很好的持续性,并进一步分析其对北半球夏季大气环流的可能影响及其物理过程。结果表明,MJJ南极海冰涛动首先通过冰气相互作用在南半球激发持续性的AAO型大气环流异常,使得南半球中纬度和极地及热带之间的气压梯度加大,在MJJ至JAS,纬向平均纬向风呈现显著的正负相间的从南极到北极的经向遥相关型分布。对流层中层位势高度场上,在澳大利亚北部到海洋性大陆区域,出现显著的负异常,在东亚沿岸从低纬到高纬呈现南北走向的“? + ?”太平洋—日本（Pacific–Japan,PJ）遥相关波列,其对应赤道中部太平洋及赤道印度洋存在显著的降水和海温负异常,西北太平洋至我国东部沿海地区存在显著降水正异常和温度负异常;低纬度北美洲到大西洋一带存在的负位势高度异常和北大西洋附近存在的正位势高度异常中心,构成一个类似于西大西洋型遥相关（Western Atlantic,WA）的结构,对应赤道南大西洋降水增加和南撒哈拉地区降水减少。从物理过程来看,南极海冰涛动首先通过局地效应影响Ferrel环流,进而通过经圈环流调整使得海洋性大陆区域和热带大西洋上方的Hadley环流上升支得到增强,海洋性大陆区域特别是菲律宾附近的热带对流活动偏强,激发类似于负位相的PJ波列,影响东亚北太平洋地区的大气环流,而热带大西洋对流增强和北传特征,则通过激发WA遥相关影响大西洋和欧洲地区的大气环流。以上两种通道将持续性MJJ至ASO南极海冰涛动强迫的大气环流信号从南半球中高纬度经热带地区传递到北半球中高纬地区,从而对热带和北半球夏季大气环流产生显著影响。 相似文献
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2011年9月大气环流主要特征如下：极涡呈单极型,中心略偏向西半球,中高纬度环流呈5波形分布,槽区分别位于北太平洋东北部、北美洲东部、北大西洋北部、欧洲东部、亚洲东北部。北太平洋东北部上空500 hPa高度场上有160 gpm的负距平。西北太平洋副热带高压面积较常年同期偏小,强度偏弱,西脊点位置偏东,脊线偏北。2011年9月全国平均气温16.4℃,比常年同期（16.0℃）偏高0.4℃;全国降水量为65.0 mm,接近常年同期（65.3 mm）。月内出现了3次较明显的冷空气过程和7次降水过程,有7个台风生成,其中＂纳沙＂登陆我国,造成重大灾害。 相似文献
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RESEARCH ON INTERANNUAL CHANGE ABOUT TELECONNECTION OF GENERAL CIRCULATION IN SUMMER DURING 1980s OVER THE NORTHERN HEMISPHERE 
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下载免费PDF全文 In the paper the 5°×10°latitude-longitude grid point data of daily 500 hPa geopotential height over the NorthernHemisphere(NH)in summer(June—August)during 1980s are used.The base point(20°N,120°E)is selected to calcu-late point correlation between the base point and other grid points.We find that the summer heat source anomaly of thetropical western Pacific causes anomaly of summer general circulation over NH and teleconnection of general circula-tion similar to PNA pattern forms from East Asia to North America.The teleconnections show great interannualchanges. 相似文献
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本文运用月降水量、500hPa、100hPa月平均高度场和海平面气压场，在对50a华北夏季旱涝等级重新评定的基础上，分析了与华北夏季旱涝年对应的环流异常特征。结果表明华北旱涝年，对应整个北半球上各层都存在显著的环流异常变化。旱年500hPa环流异常使得极涡偏心，相应乌拉尔山和北美的气候槽偏强；中纬度位于华北的平均槽东移到朝鲜日本一带，而西部脊东移控制华北；低纬西太平洋副高偏东，印度低压槽偏弱。涝年则相反。在海平面气压场上，除了在与高层对应的显著异常区有相应变化外，在我国东部大陆大部及赤道中东太平洋上也有一显著的异常区，证实夏季风和KNSO与华北旱涝存在密切的联系。在100hPa高度场旱涝年环流差异主要表现为南亚高压南北界的位置变化。 相似文献
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Sensitivity of East Asian climate to the progressive uplift and expansion of the Tibetan Plateau under the mid-Pliocene boundary conditions 总被引：3，自引：0，他引：3
A global atmospheric general circulation model has been used to perform eleven idealized numerical experiments, i.e., TP10, TP10, .., TP100, corresponding to different percentages of the Tibetan Plateau altitude. The aim is to explore the sensitivity of East Asian climate to the uplift and expansion of the Tibetan Plateau under the reconstructed boundary conditions for the mid-Pliocene about 3 Ma ago. When the plateau is progressively uplifted, global annual surface temperature is gradually declined and statistically significant cooling signals emerge only in the Northern Hemisphere, especially over and around the Tibetan Plateau, with larger magnitudes over land than over the oceans. On the contrary, annual surface temperature rises notably over Central Asia and most parts of Africa, as well as over northeasternmost Eurasia in the experiments TP60 to TP100. Meanwhile, the plateau uplift also leads to annual precipitation augmentation over the Tibetan Plateau but a reduction in northern Asia, the Indian Peninsula, much of Central Asia, parts of western Asia and the southern portions of northeastern Europe. Additionally, it is found that an East Asian summer monsoon system similar to that of the present initially exists in the TP60 and is gradually intensified with the continued plateau uplift. At 850 hPa the plateau uplift induces an anomalous cyclonic circulation around the Tibetan Plateau in summertime and two anomalous westerly currents respectively located to the south and north of the Tibetan Plateau in wintertime. In the mid-troposphere, similarto-modern spatial pattern of summertime western North Pacific subtropical high is only exhibited in the experiments TP60 to TP100, and the East Asian trough is steadily deepened in response to the progressive uplift and expansion of the Tibetan Plateau. 相似文献
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Boreal summer continental monsoon rainfall and hydroclimate anomalies associated with the Asian-Pacific Oscillation 总被引：1，自引：0，他引：1
With the twentieth century analysis data (1901–2002) for atmospheric circulation, precipitation, Palmer drought severity index, and sea surface temperature (SST), we show that the Asian-Pacific Oscillation (APO) during boreal summer is a major mode of the earth climate variation linking to global atmospheric circulation and hydroclimate anomalies, especially the Northern Hemisphere (NH) summer land monsoon. Associated with a positive APO phase are the warm troposphere over the Eurasian land and the relatively cool troposphere over the North Pacific, the North Atlantic, and the Indian Ocean. Such an amplified land–ocean thermal contrast between the Eurasian land and its adjacent oceans signifies a stronger than normal NH summer monsoon, with the strengthened southerly or southwesterly monsoon prevailing over tropical Africa, South Asia, and East Asia. A positive APO implies an enhanced summer monsoon rainfall over all major NH land monsoon regions: West Africa, South Asia, East Asia, and Mexico. Thus, APO is a sensible measure of the NH land monsoon rainfall intensity. Meanwhile, reduced precipitation appears over the arid and semiarid regions of northern Africa, the Middle East, and West Asia, manifesting the monsoon-desert coupling. On the other hand, surrounded by the cool troposphere over the North Pacific and North Atlantic, the extratropical North America has weakened low-level continental low and upper-level ridge, hence a deficient summer rainfall. Corresponding to a high APO index, the African and South Asian monsoon regions are wet and cool, the East Asian monsoon region is wet and hot, and the extratropical North America is dry and hot. Wet and dry climates correspond to wet and dry soil conditions, respectively. The APO is also associated with significant variations of SST in the entire Pacific and the extratropical North Atlantic during boreal summer, which resembles the Interdecadal Pacific Oscillation in SST. Of note is that the Pacific SST anomalies are not present throughout the year, rather, mainly occur in late spring, peak at late summer, and are nearly absent during boreal winter. The season-dependent APO–SST relationship and the origin of the APO remain elusive. 相似文献
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北半球夏季位势高度场遥相关型的观测研究 总被引：3，自引：0，他引：3
本文利用点相关普查和经验正交函数展开分析了北半球夏季500hPa位势高度场的年际变化特征,指出在北半球夏季主要存在4种遥相关型,它们分别被称作亚洲/北美型、欧亚型、东北太平洋型和北美/西欧型.其中前两种遥相关型和东亚夏季大气环流年际异常有直接的联系.北半球夏季遥相关型的揭示对于研究东亚大气环流年际变异的机理及其预报有参考价值. 相似文献
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本文利用北半球正压原始方程模式和理想初始场，加入北半球实际的平滑地形的作用，对北半球超长波2波型、3波型、长波4波型、5波型，分别进行了240小时的积分计算。从考虑地形和不考虑地形的四组结果对比中，发现地形对上述四种波型的演变有很大的影响，证实了地形作用确系影响大气环流、形成某些天气气候特征的重要因素之一；同时发现，在地形的动力作用下，北半球大气形成了一些重要的环流系统。例如，极涡向北欧偏移，东亚、北美大槽和阿拉斯加脊的维持，都与地形有密切关系。在地形作用下:（1）北太平洋西槽东脊，而北大西洋西脊东槽。（2）阻塞和切断形势的出现更为频繁、典型。（3）在欧亚大陆上，m=4时出现倒Ω流型，而m=5时，出现两槽一脊型。 相似文献
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Factors favorable to frequent extreme precipitation in the upper Yangtze River Valley 总被引：1，自引：0，他引：1
Extreme precipitation events in the upper Yangtze River Valley (YRV) have recently become an increasingly important focus in China because they often cause droughts and floods. Unfortunately, little is known about the climate processes responsible for these events. This paper investigates factors favorable to frequent extreme precipitation events in the upper YRV. Our results reveal that a weakened South China Sea summer monsoon trough, intensified Eurasian-Pacific blocking highs, an intensified South Asian High, a southward subtropical westerly jet and an intensified Western North Pacific Subtropical High (WNPSH) increase atmospheric instability and enhance the convergence of moisture over the upper YRV, which result in more extreme precipitation events. The snow depth over the eastern Tibetan Plateau (TP) in winter and sea surface temperature anomalies (SSTAs) over three key regions in summer are important external forcing factors in the atmospheric circulation anomalies. Deep snow on the Tibetan Plateau in winter can weaken the subsequent East Asian summer monsoon circulation above by increasing the soil moisture content in summer and weakening the land–sea thermal contrast over East Asia. The positive SSTA in the western North Pacific may affect southwestward extension of the WNPSH and the blocking high over northeastern Asia by arousing the East Asian-Pacific pattern. The positive SSTA in the North Atlantic can affect extreme precipitation event frequency in the upper YRV via a wave train pattern along the westerly jet between the North Atlantic and East Asia. A tripolar pattern from west to east over the Indian Ocean can strengthen moisture transport by enhancing Somali cross-equatorial flow. 相似文献
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印度夏季风的年际变异与北半球大气环流的特征 总被引：2，自引：1，他引：2
印度夏季风的年际变异是大范围大气环流相互联系、相互影响的结果。本文应用１９５１—１９８５年印度夏季风资料，选取强季风年４年和弱季风年６年，分别对北半球５００ｈＰａ高度场进行距平合成分析和复自然正交函数（ＣＥＯＦ）分析。结果指出，大西洋和鄂霍次克海阻塞高压的稳定存在以及乌拉尔山低压槽的频繁活动与强印度季风年相联系，而大西洋和鄂霍次克海低压系统的频繁活动以及欧洲阻塞高压的稳定存在与弱印度季风年相联系。印度夏季风强弱不同年份，春季北半球大气环流已经出现了一些不同特征，这对于当年夏季风的强弱和北半球气候异常有预示作用。印度夏季风强弱的不同年份和不同季节，北半球存在极地和赤道低纬位相函数大而中高纬度位相函数小，且扰动由中高纬向极地和赤道方向传播的特征 相似文献
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CHARACTERISTICS OF ATMOSPHERIC HEATING AND ATMOSPHERIC CIRCULATION DURING ACTIVE PERIOD OF 500 hPa HIGH OVER THE TIBETAN PLATEAU IN SUMMER* 下载免费PDF全文
下载免费PDF全文 Duan Tingyang 《Acta Meteorologica Sinica》1994,8(1):72-78
In correspondence with the establishment of the "upper high and lower high" pressure pattern due to the activities of 500 hPa high over the Tibetan Plateau in summer,a series of changes of the East Asia atmospheric circulation will take place.In this paper,the distributions of divergence and vertical velocity of 500 hPa high,the evolutions of atmospheric heat source,the variations of vorticity and zonal wind at 100 hPa level and vertical meridional cell over the Tibetan Plateau etc.are statistically analyzed.Thus,we can see that the ascending motion and the convective heating over the Tibetan Plateau,the South Asia high and the westerly jet on the north of the Plateau at 100 hPa level are weakned.The northern branch and the southern branch of the easterly jet on the south of the Plateau merge into a single whole and situate on the south of the former northern branch.In the meantime,thermodynamic land-sea discrepancy in South Asia and the convective heating over the Bay of Bengal is enhanced.It will play an important role in the maintenance of the easterly jet and the South Asia monsoon. 相似文献
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青藏高原增暖对东亚夏季风的影响——大气环流模式数值模拟研究 总被引：7，自引：4，他引：3
20世纪50年代以来,随着全球海表面温度年代际变化和全球变暖现象的出现,东亚夏季风降水和环流场也出现相应的年代际变化。是什么原因引起这个长期的变化趋势？研究表明青藏高原增暖可能是导致东亚夏季风年代际变化的重要因子之一。为了能够更好地理解青藏高原地表状况对下游东亚季风的影响,作者使用德国马普气象研究所大气环流模式（ECHAM）进行一系列数值试验。在两组敏感性试验中,通过改变高原上的地表反照率从而达到改变地表温度的目的。数值试验结果表明:青藏高原增暖有助于增强对流层上层的南亚高压、高原北侧西风急流和高原南侧东风急流以及印度低空西南季风;与此同时,东亚地区低层西南气流水汽输送增强。高原增暖后降水场的变化表现为:印度西北部季风降水增加,长江中下游以及朝鲜半岛梅雨降水增多;在太平洋副热带高压控制下的西北太平洋地区和孟加拉湾东北部,季风降水减少。对数值模拟结果的初步诊断分析表明:在感热加热和对流引起的潜热加热相互作用下,南亚高压强度加强,东亚夏季低层西南季风增大、梅雨锋降水增强,高原东部对流层上层的副热带气旋性环流增加,以及对流层低层的西太平洋副热带高压增强。另外,在青藏高原增暖的背景下,孟加拉湾地区季风降水减弱。本项研究有助于更好地理解东亚夏季风年代际变化特征和未来气候变化趋势。 相似文献
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基于美国环境预报中心/国家大气研究中心（NCEP/NCAR-Ⅰ）再分析资料,按照国际通行的阻塞高压（阻高）定义,采用计算机自动识别和天气图人工主、客观相结合的检测方法,获得了1979—2018年5月和6月逐日北半球中高纬度阻高活动的无缝隙分布;并利用线性相关和信息流因果关系等统计方法,研究了东北亚（鄂霍次克海）阻高与北半球其他阻高活动区特征及其联系。根据阻高活动集中程度与占北半球活动总天数的百分比,选定8个5月阻高主要活动区和10个6月阻高主要活动区。从统计结果来看,5月北太平洋、北美和乌拉尔山阻高活动占前3位,6月东北亚阻高活动天数跃升第1位。值得注意的是,初夏在贝加尔湖以南、青藏高原以北地区出现了明显的阻塞形势,称为青藏高原北阻高。5月和6月北半球各阻高活动中心集中的纬度分布,自西向东具有“正弦波”特征,其主要活动区引起的同期北半球500 hPa高度场的异常虽不尽相同,但均具有一定的遥相关特征;5月和6月东北亚阻高活动天数的年际变化分量具有明显的相对独立性。5月东北亚阻高是6月贝加尔湖阻高活动年际变化的稳定影响源,是6月青藏高原北阻高活动年际变化的不稳定影响源;唯有5月北太平洋阻高是6月东北亚阻高年际变化的稳定影响源。2019年6月北半球阻高活动异常的区域位于欧洲,达19 d,为气候平均值（7 d）的2.7倍,也是导致欧洲大陆初夏高温的主要影响系统。 相似文献