近20年华北地区干旱期大气环流异常特征   总被引：25，自引：4，他引：25       下载免费PDF全文

卫捷张庆云  陶诗言 《应用气象学报》2003,14(2):140-151

利用NCAR/NCEP再分析资料和中国气象局整编的中国160站气温、降水月平均资料, 计算并分析了1951年1月-2000年10月中国华北地区Palmer drought severity index (PDSI)。研究表明:近50年来华北干旱有显著的年际和年代际变化。从20世纪80年代以来, 华北出现了持续性严重干旱现象; 另外, 华北地区干旱持续时间一般都在两年以上。华北夏季典型干旱年的前期 (冬季和春季) 及同期环流特征是:北半球中高纬度500hPa高度距平场出现EU型遥相关分布, 华北地区长期处于大陆暖高压控制下。  相似文献   

500hPa高度场遥相关型与广东降水的关系   总被引：2，自引：0，他引：2  

黄静 《气象》2002,28(11):33-36

应用1956－2000年资料，从500hPa高度场上的相关性出发，找出了北半球（4－6月）的高度场上遥相关型，计算了它们的强度指数并分析了各遥相关型与广东降水的相关尤其是与中山市降水的关系，发现4月北太平洋型和6月北大西洋型及西大西洋型遥相关型与广东尤其是中山的降水有密切关系，而6月的西大西洋遥相关型对广东降水有很好的预测作用。  相似文献   

A STUDY ON THE VARIATION OF DROUGHT PERIODS OCCURRING IN NORTHWEST CHINA AND OTHER AFRICA-ASIA CONTINENTAL REGIONS   总被引：4，自引：0，他引：4  

Sun Guawu  Ye Qian 《Acta Meteorologica Sinica》1996,10(4):473-484

Characteristics of the drought periods which occurred in North Africa,Middle East,Middle Asiaand Northwest China were studied based on the analysis of rainfall data from 1870—1990.It is foundthat the drought periods first started in North Africa and expanded eastward to Northwest Chinathrough Middle East and Middle Asia in about 27.5 years.And then a new teleconnection pattern of30—50 day low-frequency oscillation which is associated with the droughts over the Africa-Asia Con-tinent was discovered.Finally,a hypothesis is proposed based on the statistical results that the east-ward expansion of drought periods may be caused by the occurrence of giant earthquakes(Ms>6.0)which have a tendency to shift eastward from North Africa to Northwest China in about 27.75 years.  相似文献   

1980～1983年低纬西太平洋、印度洋地区低频振荡的空间型和遥相关分析          下载免费PDF全文

温之平  梁必骐 《应用气象学报》1996,7(4):460-465

利用１９８０年１月～１９８３年１２月已滤波的ＯＬＲ资料，采用经验正交函数分析方法，对１９８０～１９８１年（正常年）和１９８２～１９８３年（异常年）低纬西太平洋和印度洋地区低频振荡的空间分布及遥相关特征进行了研究．结果表明：正常年与异常年，这些地区低频振荡的强度、空间型及时间系数的变化有较大的差异．此外，还发现正常年这些地区存在３种低频遥相关，即赤道西太平洋型，北热带西太平洋型和赤道印度洋型；异常年则仅存在２种低频遥相关，即赤道西太平洋型和南热带西太平洋型．由于受厄尔尼诺事件的影响，东西向偶极型低频振荡中心的位置和强度都有很大的变化  相似文献   

Interannual variation of the Asian-Pacific oscillation     

《Dynamics of Atmospheres and Oceans》2017

Previous studies have identified an Asian-Pacific Oscillation (APO) teleconnection pattern, which exhibits an out-of-phase relationship in the summer tropospheric temperature with warming over the Eurasia and cooling over the Northern Pacific and the Northern America, and vice versa. But the interannual variation of this teleconnection remains obscure. This study points out that interannual variation of the APO teleconnection is associated with the second empirical orthogonal function (EOF) mode of the northern-hemisphere upper tropospheric temperature during boreal summer, which accounts for 14% of the variance. A heat budget analysis is conducted for the Eurasian region and the North Pacific region respectively to reveal the cause of the zonal dipole mode temperature structure. For the Eurasia region, the warming is contributed by the adiabatic heating process due to downward vertical motion anomalies. For the Northern Pacific region, the temperature variation is mainly contributed by zonal advection associated with interannual zonal wind perturbation acting on the climatological temperature gradient. Composite analysis and numerical experiments with an atmospheric general circulation model (AGCM) shows the interannual zonal wind perturbation is related to the sea surface temperature anomalies over the equatorial eastern Pacific.  相似文献   

Interannual and Interdecadal Variations of the Mid-Atlantic Trough and Associated American-Atlantic-Eurasian Climate Anomalies     

Mengmeng Lu  Kaiqiang Deng  Guojun Zhou  Yaheng Tan 《大气与海洋》2017,55(4-5):284-292

The mid-Atlantic trough (MAT) is one of the most prominent circulation systems over the subtropical North Atlantic during the boreal summer, and it can be viewed as a bridge linking the climate in the American-Atlantic-Eurasian region. The upper-tropospheric MAT attains its maximum intensity of 200–150?hPa in June and July. An index measuring the variability of MAT intensity is defined, which reveals significant interannual and interdecadal variations of the trough.

On interannual time scales, the variation of MAT is significantly associated with the North Atlantic Oscillation, a southeastward propagating stationary wave that possibly originates from the northeastern Pacific, and the Atlantic Meridional Mode. A stronger trough is associated with warmer surface temperatures and higher pressure over central-northern North America and the extratropical North Atlantic and with colder surface temperatures and lower pressure over the Arctic, the subtropical North Atlantic, and the northeastern Pacific. In the meantime, significant negative precipitation anomalies occur over the north of the Mediterranean Sea and the Black Sea, as well as the northeastern Atlantic because of the anomalous low-level northeasterly winds over these areas. On an interdecadal time scale, the variation of MAT seems to be related to the Atlantic Multi-decadal Oscillation. Warmer surface temperatures appear over almost the entire North Atlantic, southern Europe, East Asia, and the North Pacific during the weak phase of the trough. A weak trough is also associated with the dipole pattern of anomalous precipitation over the extratropical North Atlantic, Greenland, and northeastern North America, corresponding to a dipole of low-level atmospheric circulation over these regions.  相似文献   

North Pacific SST Forcing on the Central United States “Warming Hole” as Simulated in CMIP5 Coupled Historical and Uncoupled AMIP Experiments     

Zaitao Pan  Chunhua Shi  Sanjiv Kumar  Zhiqiu Gao 《大气与海洋》2017,55(1):57-77

The central United States experienced a cooling trend during the twentieth century, called the “warming hole,” most notably in the last quarter of the century when global warming accelerated. The coupled simulations of the models that participated in the Coupled Model Intercomparison Project, Phases 3 and 5 (CMIP3/5), have been unable to reproduce this abnormal cooling phenomenon satisfactorily. An unrealistic representation of the observed phasing of the Pacific Decadal Oscillation (PDO)—one of the proposed forcing mechanisms for the warming hole—in the models is considered to be one of the main causes of this effect. The CMIP5’s uncoupled Atmospheric Model Intercomparison Project (AMIP) experiment, whose duration approximately coincides with the peak warming hole cooling period, provides an opportunity, when compared with the coupled historical experiment, to examine the role of the variation in Pacific Ocean sea surface temperature (SST) in the warming hole’s formation and also to assess the skill of the models in simulating the teleconnection between Pacific SST and the continental climate in North America. Accordingly, this study compared AMIP and historical runs in the CMIP5 suite thereby isolating the role of SST forcing in the formation of the warming hole and its maintenance mechanisms. It was found that, even when SST forcing in the AMIP run was “perfectly” prescribed in the models, the skill of the models in simulating the warming hole cooling in the central United States showed little improvement over the historical run, in which SST is calculated interactively, even though the AMIP run overestimated the anti-correlation between temperature in the central United States and the PDO index. The fact that better simulation of the PDO phasing in the AMIP run did not translate into an improved summer cooling trend in the central United States suggests that the inability of the coupled CMIP5 models to reproduce the warming hole under the historical run is not mainly a result of the mismatch between simulated and observed PDO phasing, as believed.  相似文献   

Interdecadal Variability of the ENSO–North Pacific Atmospheric Circulation in Winter     

Peng Zhang  Hua Chen 《大气与海洋》2017,55(2):110-120

The interdecadal change in the relationship between the El Niño–Southern Oscillation (ENSO) and atmospheric circulation over the North Pacific is investigated using both observational data and an atmospheric general circulation model. There are two prominent modes of winter mid-latitude atmospheric variability in the North Pacific: the West Pacific (WP) teleconnection and the Aleutian Low (AL). The relationship between ENSO and the WP-AL patterns changed notably around the late 1970s. From 1957 to 1975, during the mature phase of ENSO, significant sea surface temperature anomalies (SSTAs) occurred, mainly in the equatorial eastern Pacific Ocean; the associated atmospheric circulation anomaly pattern resembles the negative phase of a WP teleconnection pattern. In contrast, for the 1978–2011 period, significant negative SSTAs were observed in the western and extratropical Pacific in both hemispheres, with some significant positive SSTAs appearing over the eastern Pacific. This is in agreement with the defined regions of a mega-ENSO, the associated atmospheric circulation anomaly pattern resembles the AL mode. Further analysis suggests that a negative–positive anomaly pattern in the 500?hPa geopotential height throughout the entire North Pacific, possibly enhanced by the SSTAs in the extratropical North Pacific associated with the mature phase of ENSO, is responsible for modulating the relationship between ENSO and the North Pacific atmospheric circulation.  相似文献   

不同类型ENSO对东亚季风的影响和机理研究进展   总被引：6，自引：1，他引：5  

陈文  丁硕毅  冯娟  陈尚锋  薛旭  周群 《大气科学》2018,42(3):640-655

近十几年来有关热带太平洋存在不同类型的增暖型的研究成为热点课题,其中主要依据海温的空间形态将厄尔尼诺与南方涛动（ENSO）分为两类:一类为传统的东太平洋型ENSO,另一类为中太平洋型ENSO。该两类ENSO的形成机制、演变过程均有不同,产生的气候影响也有差异。本文简要回顾了国内外有关不同类型ENSO及其气候影响的研究进展,特别综述了近年来关于两类ENSO事件对东亚夏季风、东亚冬季风以及东亚冬夏季风关联的影响和机理方面的主要研究进展。文中侧重讨论了年际和年代际时间尺度上ENSO事件对东亚季风的影响,并提出了今后在该领域一些需要进一步研究的科学问题。  相似文献   

MAINTENANCE MECHANISMS OF THE STATIONARY WAVE ANOMALY TELECONNECTION PATTERNS IN THE UPPER TROPOSPHERE     

Geng Quanzhen  Huang Ronghui 《Acta Meteorologica Sinica》1998,12(3):288-299

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