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1.
4~5月南亚高压建立早晚年份环流差异及其可能成因 总被引：4，自引：2，他引：2
利用1979~2008年NCEP/NCAR逐日再分析资料和向外长波辐射(OLR)资料分析了4~5月南亚高压在中南半岛上空建立早晚年份的环流差异及可能机理。发现南亚高压建立早晚年,对流层高低层环流形势存在显著差异:在对流层高层,偏早年,菲律宾群岛以东洋面上空反气旋环流中心西移速度快,建立完成后,中南半岛上空南亚高压反气旋环流东西范围较宽,整个建立过程时间较长;偏晚年,建立开始前西太平洋上空无闭合的反气旋性环流中心,建立完成后,中南半岛上空南亚高压反气旋环流东西范围较窄,整个建立过程时间较短;在对流层低层,南亚高压建立早晚年风场和海平面气压场都呈现反相的分布形势,与之相联系的Walker环流强度也存在明显差异。中南半岛上空反气旋环流中心生成早晚与中南半岛地区对流建立发展关系密切,当中南半岛地区对流建立发展早时,中南半岛上空反气旋环流中心生成早;反之对流建立发展晚时,中南半岛上空反气旋环流中心生成晚,且中南半岛对流活跃稍早于南亚高压在该地区建立。菲律宾群岛以东洋面上空反气旋环流中心的西移快慢及有无闭合环流中心出现受该区域上空的上升运动和大气非绝热加热作用影响。当菲律宾群岛以东洋面上空的反气旋环流中心西移稳定至130°~145°E这一区域后,非绝热加热的垂直变化对该环流中心的维持及消亡起主要作用。由于前期冬春季节热带太平洋海温的异常分布,引起了后期Walker环流的强弱变化,进而影响了中南半岛至菲律宾群岛以东洋面上空的大气热力状况及上升运动,最终导致南亚高压建立期间环流的演变差异。 相似文献
2.
赤道反气旋的合成结构和涡度收支 总被引：1，自引：0，他引：1
本文通过普查1979—1983年7—9月在10°S—15°N、90°E—140°E范围内的赤道反气旋活动情况,从中选出15个强度和范围较接近的赤道反气旋进行综合分析,得到它们的平均三维结构特征。结果表明,赤道反气旋是一个暖性的中低层系统。反气旋环流与涡度、散度及垂直运动有较好的配合。在赤道反气旋的低层,环流中心为负涡度区和辐散区,并与下沉运动区相对应,四周为正涡度和辐合区,以及上升运动区。高层正好相反。加热场与垂直运动场有较好的对应关系,中心区是干绝热下沉增温区。对涡度收支的计算表明,中低层有负涡度积累,上层有正涡度积累,局地涡度变化主要决定于散度项、平流项和垂直输送项。 相似文献
3.
利用站点降水资料和再分析资料针对华南地区5—8月的持续性强降水过程,分析了低频异常非绝热加热的时空分布特征及其对低频大气环流的可能反馈作用。得到如下结论:5—6月和7—8月华南持续性强降水期间10—30 d低频非绝热加热的演变特征有所不同,5—6月持续性强降水发生前低频非绝热加热大值区从30°N(107°—115°E)以北向南传播发展至华南地区,而在7—8月降水前非绝热加热大值区从中国南海中部向西北方向传播,并在降水最强盛期到达华南。异常环流型控制着持续性强降水的强度和位置,从而决定异常凝结潜热的演变特征。异常凝结潜热则是通过影响涡度倾向变化而对大气环流有一个反馈作用。对于发生在华南5—6月和7—8月的这2组持续性强降水过程,当降水处于发展阶段,在低频非绝热加热作用项和低频涡度平流项的共同作用下,华南上空中层存在显著的10—30 d低频正涡度倾向变化,有利于低频气旋式环流的进一步发展。非绝热加热作用项主要由加热率的垂直梯度决定,涡度平流项则与气候背景风场有密切关系。5—6月持续性强降水期间涡度平流项位于非绝热加热项东侧,而7—8月持续性强降水期间涡度平流项位于非绝热加热项北侧。在持续性强降水的衰亡期,由于非绝热加热项和涡度平流项转为负值,华南被负涡度倾向变化控制,低频气旋式环流迅速消亡。 相似文献
4.
青藏高原抬升加热气候效应研究的新进展 总被引：30，自引：4，他引：26
对近4年来关于青藏高原加热影响气候的研究进行回顾.首先介绍利用位涡方程和热力适应理论,揭示;夏季高原上空低层气旋式及高层反气旋式环流结构稳定维持的动力学机理.结果表明高原加热作用造成的低层正涡源是低层气旋式环流得以稳定维持的重要原因.而边界层摩擦产生的负位涡是平衡正位涡的主要因素.高原加热还在高原上空形成负位涡,它影响着盛夏的大气环流,是青藏高原上空强大而稳定的反气旋环流得以维持的重要因素.在春夏过渡季节青藏高原非绝热加热对大气环流季节变化以及亚洲季风爆发的影响力方面,进一步确认了感热加热在过渡季节早期(5月中旬以前)环:流演变中的重要作用.青藏高原非绝热加热的时间演变引起了海陆热力差异对比的变化,使副热带高压带首先在孟加拉湾东部断裂,亚洲季风因而在孟加拉湾爆发.结果还表明,用纬向风垂直差异的时空分布能更准确地表示季节变化的区域差异.在青藏高原非绝热加热与北半球环流系统年际变化的联系方面,发现夏季青藏高原的加热强(弱)的年份,高原感热加热气泵(SHAP)高(低)效工作,使高原加热对周边地区低层暖湿空气的抽吸效应和对高层大气向周边地区的排放作用加强(减弱),高原及邻近地区的上升运动,下层辐合和上层辐散均增强(减弱),从而影响着高原和周边地区的环流以及亚洲季风区大尺度环流系统.而且高原的加热强迫还能够激发产生一支沿亚欧大陆东部海岸向东北方向传播的Rossby波列,其频散效应可影响到更远的东太平洋以至北美地区的大气环流.研究还表明,盛夏的南亚高压存在"青藏高压型"和"伊朗高压型"的双模态,它们与高原加热状态有关,且显著地与亚洲季风区的气候分布密切联系. 相似文献
5.
1998年夏季长江流域降水异常增多,发生了严重的洪涝灾害。本文利用1979-2011年的NCEP再分析月平均资料、Hadley中心的月平均海表温度资料和中国160站降水资料,分析了1998年夏季长江流域强降水的成因。结果表明：1998年夏季,印度尼西亚地区为非绝热加热正异常区,而其东北侧海域的非绝热加热为负异常或较小的正异常,由此形成了西南-东北向的异常加热梯度,使得印度尼西亚地区大气受到异常加热,低层辐合,高层辐散,而在热带西太平洋地区则为低层辐散,高层辐合,形成了西南-东北向垂直环流圈。热带西太平洋地区的低层异常辐散气流可作为异常涡度源,强迫出位于南海中国地区的反气旋性环流。同时,来自印度尼西亚北侧的扰动能量在南海地区辐合,有利于南海地区这一异常反气旋环流的维持。南海地区异常反气旋环流西北侧的西南气流,携带大量热带西太平洋及南海地区的水汽,输送到我国南方地区,并与控制中国东北地区的气旋性环流西南侧的西北气流交汇辐合于长江流域,有利于降水异常事件的产生。 相似文献
6.
Suxiang Yao Qian Huang Tim Li Chunying Zhang 《Meteorology and Atmospheric Physics》2014,123(1-2):67-79
The rainfall from January to March in 2010 in East Asia is positive anomaly and the temporal evolution characteristics present the cycle of 20–40 days. In the present paper, the low-frequency circulations and its formation mechanism are analyzed. The results show that during the peak rainfall phase, the upstream of the rainfall regions is controlled by low-frequency cyclone, and the downstream is controlled by low-frequency anticyclone in the middle and low troposphere. In the upper troposphere, the westerly jet presents the oscillation characteristics between the north and the south. Both the integrated (from the surface to 100 hPa) diabatic heating and the horizontal vorticity advection contribute to the vertical velocity. In addition, the vorticity vertical advection has effects on the vertical speed, which is a self-feedback process. The latent heating in the precipitation has influences on the westerly jet in the upper troposphere. The interactions between the precipitation and the westerly jet are mainly manifested as the intraseasonal oscillations. 相似文献
7.
副热带高压对登陆台风等熵面位涡演变影响的数值模拟研究 总被引：3，自引：1，他引：2
选取1997年第11号台风“温妮”为研究个例, 通过中尺度模式MM5模拟再现了该台风登陆后经历初期减弱、 变性及变性后再次发展的演变过程。采用Davis et al.(1996) 提出的片段位涡反演方法, 提取具有副热带高压物理意义的位涡扰动, 采用片段位涡反演的方法, 改变模式积分初始时刻台风东部副热带高压强度, 并引入Ertel等熵面位涡收支方程, 深入分析不同强度的副热带高压环流系统在登陆台风结构演变的过程中等熵面位涡的守恒性, 以及守恒性与非守恒性相对作用的大小。研究表明: 台风北上深入内陆的过程中, 高空槽大值位涡源源不断的输送使得对流层低层西北侧位涡增长, 台风中心上空的辐散形势有利于台风强度的再次增强。由于摩擦和非绝热加热的存在, 对流层位涡局地变化主要决定于位涡的水平平流 (守恒项)、 位涡的垂直平流、 加热的垂直微分 (非守恒项) 的分布。台风经历变性及再增强的过程中, 其影响范围内位涡守恒性经历了先减弱后增强的过程, 非守恒项中位涡的垂直平流能较好地描述对流层中层位涡局地变化趋势, 而加热的垂直微分则在对流层低层和高层表现良好。副高强度的加强使台风加速北上, 加快了台风变性速度, 高层位涡的向下输送明显提前且强度增强, 位涡守恒性的破坏、 重建也相应提前, 位涡垂直平流的整层负值减小, 加热垂直微分对对流层低层位涡增长的正贡献加强, 且持续时间更长。 相似文献
8.
This study examines the features and dynamical processes of subseasonal zonal oscillation of the western Pacific subtropical high (WPSH) during early summer, by performing a multivariate empirical orthogonal function (MVEOF) analysis on daily winds and a diagnosis on potential vorticity (PV) at 500 hPa for the period 1979–2016. The first MV-EOF mode is characterized by an anticyclonic anomaly occupying southeastern China to subtropical western North Pacific regions. It has a period of 10–25 days and represents zonal shift of the WPSH. When the WPSH stretches more westward, the South Asian high (SAH) extends more eastward. Above-normal precipitation is observed over the Yangtze–Huaihe River (YHR) basin. Suppressed convection with anomalous descending motion is located over the subtropical western North Pacific. The relative zonal movement of the SAH and the WPSH helps to establish an anomalous local vertical circulation of ascending motion with upper-level divergence over the YHR basin and descending motion with upper-level convergence over the subtropical western Pacific. The above local vertical circulation provides a dynamic condition for persistent rainfall over the YHR basin. An enhanced southwest flow over the WPSH’s western edge transports more moisture to eastern China, providing a necessary water vapor condition for the persistent rainfall over the YHR basin. A potential vorticity diagnosis reveals that anomalous diabatic heating is a main source for PV generation. The anomalous cooling over the subtropical western Pacific produces a local negative PV center at 500 hPa. The anomalous heating over the YHR basin generates a local positive PV center. The above south–north dipolar structure of PV anomaly along with the climatological southerly flow leads to northward advection of negative PV. These two processes are conducive to the WPSH’s westward extension. The vertical advection process is unfavorable to the westward extension but contributes to the eastward retreat of the WPSH. 相似文献
9.
The studies in China on the formation of the summertime subtropical anticyclone on the climate timescale are reviewed. New insights in resent studies are introduced. It is stressed that either in the free atmosphere or in the planetary boundary, the descending arm of the Hadley cell cannot be considered as a mechanism for the formation of the subtropical anticyclone. Then the theories of thermal adaptation of the atmosphere to external thermal forcing and the potential vorticity forcing are developed to understand the formation of the subtropical anticyclone in the three-dimensional domain. Numerical experiments are designed to verify these theories. Results show that in the boreal summer, the formation of the strong South Asian High in the upper troposphere and the subtropical anticyclone over the western Pacific in the middle and lower troposphere is, to a great extent, due to the convective latent heating associated with the Asian monsoon, but affected by orography and the surface sensible heating over the continents.On the other hand, the formation of the subtropical anticyclone at the surface over the northern Pacific and in the upper troposphere over North America is mainly due to the strong surface sensible heating over North America, but affected by radiation cooling over the eastern North Pacific. Moreover, in the real atmosphere such individual thermal forcing is well organized. By considering the different diabatic heating in synthesis, a quadruple heating pattern is found over each subtropical continent and its adjacent oceans in summer. A distinct circulation pattern accompanies this heating pattern. The global summer subtropical heating and circulation may be viewed as “mosaics” of such quadruplet heating and circulationpatterns respectively. At last, some important issues for further research in understanding and predicting the variations of the subtropical anticyclone are raised. 相似文献
10.
海陆分布对海气相互作用的调控和副热带高压的形成 总被引：7，自引：3，他引：4
首先回顾了近年来关于副热带高压形成和变异研究的若干动力学进展,阐明夏季副热带“四叶型”LOS-ECOD加热分布型的内涵。在此基础上研究海陆分布对海气相互作用的调控,揭示了“四叶型”加热形成的物理基础,并进一步阐明“四叶型”加热拼图及其与副热带高压形成和变异的联系。 文章还回顾了关于副热带高压中短期变异的动力研究的最新进展。给出了影响中国江淮流域持续性降水的副热带高压三维结构的空间分布型;指出东西风带扰动的传播和高／低纬扰动的正压发展是影响副热带高压变异和中国夏季降水的一种可能机制,最后证明青藏高原夏季的强加热能激发纬向非对称不稳定发展,产生南亚高压的东／西部型双模态及准双周振荡。还证明初夏低纬的强对流降水／台风也能激发纬向非对称不稳定发展,影响西太平洋副热带高压异常和中国淮河流域的持续性降水。 相似文献
11.
Tracing the boundary layer sources of carbon monoxide in the Asian summer monsoon anticyclone using WRF-Chem 总被引：1，自引：0，他引：1
The Asian summer monsoon(ASM) anticyclone is a dominant feature of the circulation in the upper troposphere–lower stratosphere(UTLS) during boreal summer, which is found to have persistent maxima in carbon monoxide(CO). This enhancement is due to the upward transport of air with high CO from the planetary boundary layer(PBL), and confinement within the anticyclonic circulation. With rapid urbanization and industrialization, CO surface emissions are relatively high in the ASM region, especially in India and East China. To reveal the transport pathway of CO surface emissions over these two regions, and investigate the contribution of these to the CO distribution within the ASM anticyclone, a source sensitivity experiment was performed using the Weather Research and Forecasting(WRF) with chemistry model(WRFChem). According to the experiment results, the CO within the ASM anticyclone mostly comes from India, while the contribution from East China is insignificant. The result is mainly caused by the different transportation mechanisms. In India,CO transportation is primarily affected by convection. The surface air with high CO over India is directly transported to the upper troposphere, and then confined within the ASM anticyclone, leading to a maximum value in the UTLS region. The CO transportation over East China is affected by deep convection and large-scale circulation, resulting mainly in transportation to Korea, Japan, and the North Pacific Ocean, with little upward transport to the anticyclone, leading to a high CO value at215 h Pa over these regions. 相似文献
12.
采用美国NCEP/NCAR I、NCEP/DOE II和日本气象厅JRA-55（Japanese 55-year Reanalysis Project）的月平均环流场和非绝热加热场资料,分析了夏季南亚高压多中心结构特征,探讨了不同区域高压中心的动力和热力结构,及其与不同地区热源的关系。结果表明:（1）夏季南亚高压存在显著多中心特征,可达5～6个,其中双中心类和三中心类占比例最多,约70%～80%,其次,单中心类和四中心类分别约占10%左右。（2）无论中心个数的多或少,不同区域的南亚高压中心的动力结构和热力结构不同,大致可以分为三个区域20°～70°E、80°～120°E和120°～160°E。20°～70°E伊朗高原及其以西上空南亚高压中心中层对应伊朗副高的东北侧,低层对应印缅槽的西北部,整层为下沉运动;80°～120°E青藏高原到我国东部上空南亚高压中心低层对应印缅槽中部,低层正涡度高层负涡度,整层为强上升运动;120°～160°E西太平洋地区南亚高压中心中低层都对应西太平洋副热带高压的西部,整层负涡度,对应上升运动。（3）三个区域的高压中心都对应着暖中心结构,20°～70°E区域以下沉增温加热为主导,80°～120°E和120°～160°E区域以深对流加热为主导。（4）当20°～70°E、80°～120°E和120°～160°E区域存在高压中心时,对应区域的南亚高压环流的增强,对局地环流、深对流和降水有着显著的影响。 相似文献
13.
The synoptic and dynamic aspects of heavy rainfall occurred on 5th May 2017 and caused flash flooding in arid and semi-arid central-northern Iran is analyzed by the Weather Research and Forecasting (WRF) model. This system synoptically is attributed to a surface low-pressure centered over southern Iran extended to the central parts, linking to a mid-tropospheric tilted-trough over western Iran, and advecting significant moisture from the Mediterranean Sea and the Red Sea to the studied area. The dynamical analysis revealed that the penetration of the upper-tropospheric potential vorticity streamer up to 300 hPa level was not related to such heavy rainfall. Contrarily, the low-level factors such as extensive moisture advection, mid-tropospheric diabatic processes such as the latent heat release, daytime deep convection, and topographical impact of Zagros Mountains were found as the key factors leading to this system. This study also examines 11 different convection schemes simulated by the WRF model and verified against rainfall observation. The forecast skills of the output simulations suggest the Grell-Devenyi scheme as the superior configuration in simulating observed precipitation of the event over the area. 相似文献
14.
A NUMERICAL STUDY ON FORMATION OF THE NEGATIVE VORTICITY REGION OVER THE NORTHEAST SIDE OF THE QINGHAI-XIZANG PLATEAU* 
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下载免费PDF全文 In order to investigate the formation of the negative vorticity region over the northeast side of the Qinghai Xizang (Tibetan) Plateau,four sets of numerical experiments have been performed in this paper with a quasigeostrophic barotropical model considering large-scale topography,diabatic heating and dissipation.The diabatic heating in the model contains a constant forcing and timevarying forcing.The time-varying characters are determined by the continuous evolution of the sensible heat flux at Damxung Station (30°29'N,91°06'E) from 31 May to 4 June 1998.Results suggest that there are three types of processes significantly contributing to the formation of the negative vorticity region over the northeast side of the Qinghai Xizang Plateau,and they are the advection of the anticyclonic vortex at the upstream by the basic flow,the energy dispersion of the cyclonic vortex over the south side of the Plateau,and the strengthening of anticyclonic systems produced by the thermal forcing of the Plateau. 相似文献
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Summary The Southern South America climatological 500 hPa relative vorticity mean state was examined using regional objective analyses
of 500 hPa geopotential heights provided by the Servicio Meteorológico Nacional of Argentina. The dataset, covering the period
June 1983 to July 1987, was stratified into two samples: the cold and warm seasons. Mean cyclonic vorticity south of 40° S
results in a climatological trough over Patagonia with a northwest-southeast tilt. North of this latitude, mean anticyclonic
circulation dominates with the exception of a centre of cyclonic vorticity over the Río de la Plata (35° S, 56° W). Seasonal
changes appear to be small. Relative vorticity frequency distributions were also analysed.
The association between precipitation and synoptic-scale features of the mid-troposphere circulation was investigated through
vorticity fields. A particular distribution of vorticity anomalies associated with daily precipitation in Buenos Aires is
revealed by biserial correlation coefficient fields. In winter, the strongest relationships are found between 35° S and 40° S
over the Andes Mountains (minimum significant correlation coefficients indicating a cyclonic vorticity anomaly), and in the
south of Brazil and east of Buenos Aires over the Atlantic Ocean down to a latitude of 40° S (maximum correlation coefficients
related to anomalously anticyclonic circulation). This shows the preferential position of troughs and ridges that produce
precipitation in Buenos Aires on the time scale of a day. In summer, centres of anomalously cyclonic and anticyclonic vorticity
associated with precipitation shift slightly southward. For moderate or intense precipitation in Buenos Aires, advection of
warm and wet air southwards appears to be more important in winter, while in summer the strong anomalous vorticity gradient
north of the negative centre over the Andes Cordillera favours rainfall in Buenos Aires.
Received April 17, 1997 相似文献
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To carry out this research, interpolated data of daily rainfall from Iran’s Asfazari data base during 1/1/1979–31/12/2013 is used. The day along with pervasive rainfall considered a day that at least 50% of Iran’s territory has received more than 1 mm for at least two consecutive days. Based on mentioned thresholds, 224 days selected for statistical analysis. The sea level pressure data, zonal and meridional wind components and specific humidity with spatial resolution of 0.25*0.25 Gaussian degree in spatial domain of 10 °N to 60 °N and 15 °E to 75 °E obtained from the European Center for Medium range Weather Forecasting (ECMWF) ERA-Interim for selected days. Then on the data matrix of sea level pressure, the cluster analysis by Ward linkage method done and 4 sea level pressure patterns with different configuration of synoptic systems were identified. The findings showed that in the sea level, the interaction between southern thermal low pressure systems (Arabia low pressure) with Europe and Siberia cold immigrant high pressure both by individual and integration and anticyclone circulation of Arab sea from the low level of 1000–500 hPa of troposphere have the most role on occurrence of durable and pervasive rainfall of Iran. The most Vertically Integrated Moisture Flux Convergence in the first layer of troposphere (1000–850 hPa) observed in low height regions, in the second layer of troposphere (775–700 hPa) on Zagros Mountains and in third layer of troposphere (600–500 hPa) is seen in mountains leeward of Iran. Also the results showed that the maximum rainfall cores has the most coordination with Vertically Integrated Moisture Flux Convergence (VIMFC) in the second layer of troposphere (775–700 hPa) on the Zagros heights in the southwest of Iran. 相似文献
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海洋性大陆核心区域非绝热加热年代际变化及其与东亚夏季风变异的可能联系 总被引：2，自引：4，他引：2
海洋性大陆区域是太平洋和印度洋通过“大气桥”发生相互作用的区域,也是亚洲季风和澳洲季风相互作用的重要地区。利用1979—2012年的NCEP/NCAR、CMAP月平均资料和合成分析等方法,研究了海洋性大陆核心区域非绝热加热年代际变化规律及其与东亚夏季风的可能联系。海洋性大陆地区气候变动在95~145 °E,10 °S~10 °N区域尤为显著,记此区域为海洋性大陆核心区域（即KMC区域）。不考虑大气中潜热释放时,KMC区域的非绝热加热率在1979—2012年之间存在显著的年代际变化,加热作用由弱增强,在1980年代末期达到峰值后,即转为减弱阶段。对非绝热加热异常各分量的分析发现,在KMC区域,表面潜热和净大气长波辐射起主要作用。当非绝热加热负异常时,KMC区域的陆地降水偏多,海洋上降水偏少,赤道上存在气流辐合。在115~120 °E区间平均的经圈剖面上,气流在赤道地区上升、南海下沉、30 °N处上升,构成了异常的垂直环流圈。水汽从孟加拉湾、南海地区向中国东部输送,利于产生降水正异常。东亚剖面上的经圈环流在联系KMC区域非绝热加热和东亚夏季风异常的年代际变化中起重要作用。 相似文献
18.
The Maritime Continent(MC) is an important region where the Tropical Pacific and the Indian Ocean interact with each other via "the atmospheric bridge" and a key region for the interaction between the Asian and Australian monsoons. Using the NCEP/NCAR and CMAP monthly mean reanalysis over the period of 1979-2012, the interdecadal variations of diabatic forcing over the key region of the Maritime Continent and its possible relations with the East Asian summer monsoon have been investigated in the present paper. Our results show that climate variations in the Maritime Continent is particularly significant in the area of 95-145°E, 10°S-10°N, which is thus defined as the key area of the MC(i.e., KMC area). Without the input of latent heat release in the atmosphere, distinct interdecadal change of diabatic heating is found to exist from 1979 to 2012; it intensified before 1980 s and peaked in the late 1980 s and weakened after this period. By analyzing each individual component that contributes to the diabatic heating in the KMC area, surface latent heat flux and net long-wave radiation in the atmosphere are found to be the two dominant components. With negative diabatic heating anomalies over KMC, there will be more precipitation on islands and less precipitation over sea, and more rainfall around the equator, which is in correspondence with the convergence center around the equator in the KMC area. Along the meridional-vertical section averaged between 115-120 ° E, the well-defined vertical circulation anomalies are observed with the ascending branches over KMC and the area around 30°N respectively, and the descending branch over the South China Sea. Water vapor transports from the Bay of Bengal and South China Sea to eastern China to benefit the positive precipitation anomalies. The meridional-vertical circulation in East Asia plays a critical role in linking the interdecadal variability of diabatic heating over the KMC and East Asian summer monsoon anomalies. 相似文献
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利用NCEP/NCAR再分析资料、Hadley中心海温资料及CMAP降水资料等,通过亚澳季风联合指数挑选异常年份,对东亚夏季风和澳洲冬季风强度反相变化特征进行研究。结果表明,当东亚夏季风偏强、澳洲冬季风偏弱时,南北半球中低纬地区都出现了复杂的异常环流系统。在热带地区对流层低层,西北太平洋为异常反气旋式环流系统所控制,与南太平洋赤道辐合带的异常反气旋环流在赤道地区发生耦合,形成赤道异常东风,而在南北印度洋上则存在两个异常气旋式环流系统。在这两对异常环流之间的海洋性大陆地区,出现赤道以南为反气旋环流而赤道以北为气旋式环流。在东亚季风区,东南沿海的东侧海洋上存在反气旋异常,中国东南地区受异常反气旋西南侧的东南风影响。此外,澳洲北部受异常西风影响。这就形成了东亚夏季风偏强、澳洲冬季风偏弱的情形,从而东亚夏季风和澳洲冬季风活动出现了强弱互补的变化特征。当东亚夏季风偏弱、澳洲冬季风偏强时,南北半球的环流特征则出现与上述相反的环流特征。总体而言,当东亚夏季风偏强、澳洲冬季风偏弱时,东亚—澳洲季风区在南北半球呈现出不同的气候异常分布特征,即北半球降水北少南多、气温北高南低,南半球降水西多东少、气温西高东低。 相似文献
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亚洲夏季风建立前后对流层温度场演变特征及其热力成因 总被引：5，自引：1，他引：4
对１９９６年亚洲夏季风爆发前后（３～６月）印度及南海季风区对流层温度演变特征及其热力成因作了比较分析。结果表明：印度和南海夏季风的爆发与各季风区对流层中上层南北温差逆转密切相关,而南北温差逆转是由１０～３０°Ｎ之间纬度带对流层的季节性增暖引起的。夏季风爆发前期,南海季风区的增温主要由暖平流及非绝热加热过程（主要为凝结潜热）共同作用所致。春季在印度季风区大陆上空存在显著的下沉绝热增温,使得对流层中上层的增温率比华南大陆及邻近地区上空的增温率显著得多。但印度季风区冬末春初的南北温差（南暖北冷）也非常明显,以至该地区对流层中上层增暖到引起南北温差发生逆转的时间较迟,而南海季风区对流层中层南北温差发生逆转的时间相对要早,因而印度夏季风比南海夏季风迟爆发。 相似文献