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本文利用P—σ混合坐标系原始方程模式对夏季东半球中低纬的气象场相非绝热加热场进行了数值模拟。从模拟得到的日平均温压场、流场及降水量场与实况的对比分析中可以发现,高空300hPa的南亚高压、海平面大陆低压这一对夏季东半球的半永久性气候系统,对流层低层以索马里急流为主的越赤道气流均被成功地模拟出来了。降水量的模拟基本上也是成功的,但从降水的性质来看,有明显不足的是热带海洋地区的对流性降水。 在气象场基本符合实况的前提下,文章讨论了非绝热加热场的分布特征及其性质。指出大陆是热源区,其中90°E以东的加热场是大尺度凝结加热的贡献,大陆西部的加热区是以感热加热为主。模拟较差的是热带海洋区。 相似文献
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全球大气季节平均热源的三维分布——非绝热加热与瞬变加热之对比 总被引：2，自引：0，他引：2
利用1958—2001年ERA40逐日大气再分析资料,使用热力学方程剩余项法计算和对比分析了全球大气季节平均非绝热加热和瞬变加热的四季气候平均三维分布。结果表明,全球大气非绝热加热主要为热带强大深厚对流性热源、中纬度浅薄热源以及副热带和高纬度的深厚性热汇,热带热源总是向夏半球偏移,但中纬度热源和高纬度热汇在冬半球偏强。全球大气瞬变加热的三维分布主要表现为:副热带热汇-中高纬度热源的南北偶极型和中纬度低层热汇-高层热源的高低层偶极型,该分布型导致瞬变热源具有从高纬度低层向中纬度高层的倾斜结构。瞬变加热与风暴路径密切相关,冬半球风暴路径的瞬变活动强,因而其瞬变热源和热汇也强,而夏半球则相对弱。瞬变加热在北半球具有位于大陆东部和大洋西部的区域性特征,而在南半球具有纬向带状分布,尤其在冷季时南太平洋瞬变热汇和热源带出现分离现象。瞬变加热在全球大部分区域对非绝热加热起减弱抵消作用,但在中纬度对流层中高层起支配性作用。因此,大气瞬变活动帮助高纬度和中纬度中高层大气获得更多的热量,从而对非绝热加热造成的大气热量进行空间上的重新分配。 相似文献
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定常条件下感热和地形影响的Rossby波 总被引：5，自引：0，他引：5
通过在非绝热准地转线性模式中引入波动形式解,并确定适当的定解条件,用正交模方法求得了感热波的波动解。结果表明由于感热加热集中于近地层附近,其波动解具有与山脉波类似的波动垂直结构,波动等位相线随高度向西倾斜,波动能量向上传播。对NCEP/NCAR资料的分析验证了理论推导结果的合理性。大尺度大气定常波随纬度和季节有明显变化。热带地区定常波主要受潜热加热影响,副热带地区大气波动常表现为地形、潜热和感热加热的综合效应,而中纬度地区大气定常波则主要由地形和感热加热决定。 相似文献
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定常辐散场产生的涡源和定常波能量传播 总被引：1，自引：0，他引：1
根据ECMWF1980～1988年的全球资料，确定了南北两半球对流层上层定常的辐散风所形成的定常涡源的位置、定常波能量传播路径及它们的位置关系，讨论了涡源的形成机制。由此揭示了热带西太平洋积云对流加热、风暴路径上的潜热释放、欧亚大陆冷源及青藏高原热力和动力作用等主要外源在冬夏南北半球定常波形成中的作用。 相似文献
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本文利用一个包含了Newton冷却、Rayleigh摩擦以及▽~4型水平扩散等耗散作用的定常、斜压、线性初始方程三维谱模式,研究了热带和中纬度理想热源以及1979年1月北半球平均非绝热加热场对于冬季行星尺度的大气定常波的影响。数值试验结果表明,热力强迫作用的重要性可以与北半球大地形的动力强迫作用相比拟。利用1979年1月平均加热场作为强迫函数计算得到的强迫扰动,主要表现为纬向波数为2的行星波,并具有明显的斜压结构。热带地区纬向非均匀热源所激发的近似地沿大园路径传播的Rossby波列,对于热带区域与中、高纬大气之间的遥相关现象提供了一种可能的解释,同时,热带外区域的加热场对于整个半球范围内定常波的维持有着更显著的贡献。 相似文献
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本文基于多套卫星观测数据和ERA-Interim再分析资料,分析了由冬至夏北半球副热带地区大气热源的季节转换特征及其原因。结果表明,北半球副热带大陆东部以对流凝结潜热为主的夏季型大气热源首先于4月初在我国南方地区建立,该过程与江南雨季的形成发展联系紧密。2~3月,江南地区的大气热源以感热加热为主,这时降水以大尺度层云降水为主;而在4月初之后,江南地区降水以对流性降水为主,相应地对流凝结潜热成为大气热源的主要成分。动力和热力诊断分析说明,青藏高原南部热力状况的季节变化是导致4月初江南地区降水性质和大气热源首先发生季节转换的重要原因。2~3月,随着太阳辐射逐渐增强,青藏高原地面感热随之加强,此时对流层中部的纬向西风令江南地区的对流层中部暖平流加强,引起上升运动并加强局地大尺度层云降水,令土壤湿度加大,为随后局地对流性降水的快速发展提供了有利条件。之后,青藏高原地面感热在4~5月期间继续加强,这时高原南坡的"感热气泵"令其四周的低空水汽向北辐合,从而加强了江南地区的低空南风,使大量水汽自南海-西太平洋向北输送,令江南地区的对流性降水快速发展,地面感热迅速减小,对流凝结潜热进而成为江南地区大气热源的主要成分。 相似文献
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本文利用1961—1974年7月的平均资料,对45°N—40°S范围计算了各种平均经圈环流及加热场等物理量。所取的网格点为5°× 5°经纬度,垂直速度利用实际风计算,加热场是用热流量方程计算的。 由研究发现海陆分布及高原对平均经圈环流的影响是明显的,在南北半球大范围比较均一对称的下垫面上空,如欧非大陆、大西洋及东太平洋上空都存在一个典型的南北半球对称的Hadley环流。在北面是大陆高原,南面是海洋的亚洲地区,只有一个典型的季风环流。这是因为北半球副热带区的冷源变为热源,Hadley环流消失之故。西太平洋也有一类似的季风环流,这与这个地区存在较强的热源有关。北美季风环流很弱主要因为北美副热带陆地面积远比亚洲小。北半球全球的Hadley环流都很弱,主要是受季风环流的影响。 另外,还发现亚洲季风环流区,向上输送的能量很强,尤其高原地区更强更高,它在高空向东西两侧及南半球输送。 相似文献
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春夏季节转换中亚洲季风区副热带高压断裂特征及其可能机制分析 总被引：5，自引：2，他引：5
分析了春夏转换季节中亚洲季风区北半球副热带高压断裂的气候学特征及其可能机制。分析表明,北半球副高断裂最先发生在孟加拉湾中南半岛一带。孟加拉湾和中南半岛地区经圈环流的季节转换在高低层存在差异。在3~5月的经圈环流演变中,孟加拉湾地区经圈环流表现为对流层低层首先发生改变,呈高、低层正、反Hadley环流配置,大气加热以感热为主,因而高度场表现出的副高在孟加拉湾首先断裂只是对流层低层的表现。中南半岛则表现为从低到高的整层上升运动增强,经圈环流的减弱、消失是地表感热和潜热共同作用的结果,因而整个对流层副高的断裂应在中南半岛地区。中纬度亚洲大陆积雪季节溶化以高原为中心表现出东快西慢特征,导致105 E以东的东亚中纬度感热首先增加,地表感热加热大气的结果有利于大气经圈环流下沉气流减弱,从而加剧了中南半岛地区经圈环流减弱进程,为北半球副高在孟加拉湾中南半岛地区断裂提供了大尺度气候变化背景。 相似文献
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In this paper, the nonlinear stationary waves forced by topography and diabatic heating are investigated. It is pointed out
that (1) the nonlinear interaction of different stationary waves forced only by topography might form dipole blocking in the
atmosphere, this might explain the dipole blocking appeared in the Pacific and Atlantic regions; (2) the dipole blocking could
not be caused by the nonlinear interaction of the different stationary waves forced by the diabatic heating alone; (3) the
nonlinear interaction of the diffferent stationary waves forced by both topography and diabatic heating could initiate dipole
blocking in the atmosphere. In winter, the dipole blocking mainly occurs in the west regions of the Pacific and the Atlantic,
and the heat source over the western part of the two oceans is advantageous to the formation of dipole blocking in the west
of two oceans. However, in summer, the dipole blocking could be formed in the east part of the two oceans, and the heat source
over the eastern part of two continents is favourable for the formation of dipole blocking in the east regions of two oceans. 相似文献
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In this paper, the nonlinear stationary waves forced by topography and diabatic heating are investigated. It is pointed out that (1) the nonlinear interaction of different stationary waves forced only by topography might form dipole blocking in the atmosphere, this might explain the dipole blocking appeared in the Pacific and Atlantic regions; (2) the dipole blocking could not be caused by the nonlinear interaction of the different stationary waves forced by the diabatic heating alone; (3) the nonlinear interaction of the diffferent stationary waves forced by both topography and diabatic heating could initiate dipole blocking in the atmosphere. In winter, the dipole blocking mainly occurs in the west regions of the Pacific and the Atlantic, and the heat source over the western part of the two oceans is advantageous to the formation of dipole blocking in the west of two oceans. However, in summer, the dipole blocking could be formed in the east part of the two oceans, and the heat source over the eastern 相似文献
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Abstract The seasonal cycle of the GLAS/U of Maryland GCM is analysed in terms of the behaviour of the monthly and seasonal mean fields and the structure of the annual harmonic. (The stationary and transient eddies are treated in a companion paper.) Both polar regions at upper levels are much too cold in the annual mean, leading to excessive zonal winds above 200 mb. The problem is present in all seasons, but is most severe in local winter. A compensating belt of warm temperatures at lower latitudes is found. It is argued that the inclusion of gravity wave drag is not necessarily the solution to this problem. The simulated annual harmonics of Northern Hemisphere sea‐level pressure and 200‐mb heights are realistically intense over the eastern continents and weak over the eastern oceans. Problems in the simulation include the anomalously deep Aleutian low and the low values of the height over Europe, both occurring in winter. The simulation of the annual harmonic in sea‐level pressure and 200‐mb heights in the Southern Hemisphere is realistic. The GCM fails to show the observed amplitude of the annual harmonic in 200‐mb temperature over Antarctica. The GCM precipitation is too intense over land, particularly in summer. It is suggested that the problem is related to the parametrizations of moist convection and the boundary layer. The seasonal patterns of precipitation over the western tropical Pacific are generally realistic. There is no evidence that the GCM systematically underestimates momentum flux convergence. 相似文献
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RESPONSE OF TROPICAL ATMOSPHERIC CIRCULATION TO THE OCEAN-LAND SURFACE HEATING——AN ANALYTICAL SIMULATION 
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下载免费PDF全文 A linear steady model is constructed to investigate the response of the tropical atmosphere to diabaticheating.The basic equations are similar to those used by Gill(1980),but the long-wave approximationis removed and periodic boundary conditions are taken in longitude.According to the features of theunderlying surface temperature(including oceans and land),the heat sources(sinks)are given.Using thisanalytical model,we have simulated the climatological fields of wind and air pressure in the lower layersof the tropical and subtropical atmosphere in summer(June—August)and winter(December—February).The main features of observations are depicted in simulated fields. 相似文献
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Yong. L. McHall 《大气科学进展》1991,8(2):225-236
The contribution of thermal forcing to the planetary stationary waves will be studied also by assuming that heat balance in stationary waves over zonally asymmetric thermal forcing must be maintained over a long time period. Us-ing the same model of geostrophic waves introduced in Part I, we may explain successfully the observed and simulated responses to the thermal forcing in the atmosphere, such as the wave 1 structure at high levels of middle latitudes, the seasonal changes of the stationary waves in the Northern Hemisphere, the opposite phase distributions of stationary waves at high and low levels of the subtropical regions in both hemispheres and so on. 相似文献
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Abstract This paper presents the seasonal dependence of the stationary and transient eddies of the GLAS/UMD GCM from a two‐year annual cycle integration. The simulated Northern Hemisphere stationary waves are realistic in winter (below 250 mb) and in spring and fall; in winter a large anomalous ridge over the date‐line is noted above 250 mb. The model does not simulate the winter barotropic trough over eastern Canada. In summer the mid‐latitude stationary waves are poorly simulated (possibly owing to anomalous summer rainfall), but the monsoonal structure in the tropics is captured. The stationary wave field at 500 mb in the Southern Hemisphere is not well simulated, with the range of season‐to‐season variability being much larger than observed. The zonally averaged stationary wave rms is realistic below 200 mb in winter and spring, but is less so in summer and autumn, possibly due to erroneous summertime precipitation. The geographical distributions of 500‐mb transient and band‐pass height rms, of transient 850‐mb heat flux and of 200‐mb momentum flux in the Northern Hemisphere are well simulated except for summer. The latitude‐height dependence of height rms and low‐level transient heat flux is realistic in both summer and winter, but the transient momentum flux is not well simulated in summer. The mid‐level transient heat flux is too strong. The overall pattern of transient activity at 500 mb in the Southern Hemisphere is reasonable in the GCM, although there is too much variability in the eastern Pacific, while the observed peak in rms in the New Zealand sector is displaced eastwards in the GCM. The latitude‐height dependence of transient height rms and transient fluxes of heat and momentum looks quite realistic, and is similar in accuracy to the Northern Hemispheric results. 相似文献
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It is discussed that the anomaly in long-range weather is due to the stable sustained circulation.Waveson monthly or seasonal departure maps can essentially be regarded as probability waves which reflectthe anomaly distribution of heat sources and sinks on the earth's surface.The persistent stable circulationcreats these distributions which serve as persistent disturbance sources and in turn feedback the generalcirculation with persistent stability in later period.The departure probability waves on a six-month (September—February)chart reflect the anomalous dis-tribution of heat sources and sinks on the underlying surface.The waves north of 30°N move slowly andeastward on the Eurasian Continent against the temperature gradient,while they are stationary south of 30°N.A statistical model is developed to predict the spring—summer temperature and precipitation of next yearby using the six-month departure probability wave of last year.During 1982--1985 it was tested in severalprovinces of northern China with encousaging results. 相似文献
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The spatial structure and temporal variations of the stationary wave anomalies in the uppertroposphere during the Northern Hemisphere winter are studied with the ECMWF data of 1980—1988 and PCA(principal component analysis)method.The vorticity source anomalies of the mainteleconnection patterns are analyzed,and their roles in the maintenance of the stationary waveanomaly teleconnection patterns are investigated with the harotropic model.The results show thatthe anomalies of transient vorticity flux convergences tend to cancel the anomaly of vorticitysources generated by divergent winds.The stationary wave anomaly patterns caused by divergentwind anomalies only are very different from observations.However,if the anomalous transientvorticity flux convergences are also included in the vorticity sources,the simulated patterns will begreatly improved. 相似文献
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从海平面气压场的波谱分析比较南、北半球大气环流的变化 总被引：2，自引：1，他引：2
本文应用沿纬圈的谐波分析,对1951—1960年各年逐月南、北半球海平面气压进行分解,对比两个半球的副热带(30°N,30°S)及中纬度(50°N,50°S)的超长波活动发现:(1)南、北两个半球月平均大气环流都存在有性质不同的两类变化,即季节性变化与非季节性变化。在海陆对比明显的北半球,不论西风带还是副热带季节性变化都比较清楚。而南半球仅副热带季节性变化明显,西风带则是非季节性变化占优势。(2)南、北两个半球大气环流的季节变化,都有明显的年际差异。通常,北半球夏季建立(南半球是夏季结束)的年际差异大,北半球夏季结束(南半球是夏季建立)的年际差别较小。(3)超长波位置的年际变化与海陆分布有密切关系。陆地面积大的地区,占优势的超长波位置比较稳定,在几乎全为海洋的50°S,则超长波无论占优势与否,波槽位置的年际变化都较大。 相似文献
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ANALYSIS ON THE SOURCE AND SINK OF KINETIC ENERGY OF ATMOSPHERIC 30-60 DAY PERIOD OSCILLATION AND THE PROBABLE CAUSES* 下载免费PDF全文
下载免费PDF全文 Based on ECMWF daily grid point data in summer(May-August),1981,the distribution features of the source and sink of kinetic energy of atmosphere 30-60 day oscillation,including its horizontal distribution characteristics and its vertical structure characteristics,are investigated systematically with diagnostic analysis methods over a latitude belt between 80°N and 60°S.Also,the probable reasons for the existence of the source and sink of low frequency kinetic energy(LFKE) are discussed preliminarily.Results show that the horizontal distribution of the sources and sinks of kinetic energy of atmospheric 30-60 day oscillation is extremely different.The significant sources and sinks of LFKE mainly exist in the oceans and the coastal regions of continents or islands in the mid-high latitudes.It is also found that,in the vertical direction,the sources and sinks of kinetic energy of 30-60 day oscillation display barotropic structure in the mid-high latitudes of both hemispheres,but dispaly baroclinic structure in the equtorial region,and in the horizontal direction,the sources and sinks mainly display zonal wave-like distribution.The source and sink of LFKE are determinded by ageostrophic wind effect,frictional effect,interaction between sub-grid-scale systems,nonlinear interaction,and the flux-divergence of LFKE transported by transient wind.There are some regional reasons for the generation of sources and sinks which are not completely identical in different areas. 相似文献