THE DECADAL CLIMATE VARIABILITY AND THE ANOMALOUS ENSO DEVELOPMENTS IN 1990S^*          下载免费PDF全文

ZHANG Qin  DING Yihui  YI Lan 《Acta Meteorologica Sinica》2002,16(1):1-20

By using the wavelet transform method,the ENSO (2-7 a) signal and the decadal variability (8-20 a) are filtered out from the long-term SST data sets in order to investigate characteristics of the decadal variability and its impact on the ENSO.It is found that there are two different kinds of decadal SSTA modes-horseshoe and horse saddle patterns in the tropical Pacific.The horseshoe pattern represents that the decadal SSTA variability in the central Pacific is in phase with that in the eastern Pacific.The horse saddle pattern is named that they are out of phase.The former constituted the decadal variability before 1990s and the latter mainly prevailed during 1990s.As the response of atmosphere to the ocean,two decadal wind patterns appear in association with the SST decadal modes.One is characterized by anomalous development of the zonal wind,the other by anomalous development of the meridional wind.These two kinds of modes can also be regarded as different phases of the decadal oscillation.Further studies have shown that the influences of the two kinds of modes on the ENSO are different.The horse saddle mode has a stronger impact on the ENSO than the horseshoe mode.A possible mechanism for the influence of the decadal variability on the ENSO signal is presented.The central part of the thermocline along the equatorial Pacific moves up or down simultaneously with its eastern part while the decadal variability bears the horseshoe pattern.But the two segments of the thermocline in the central and eastern Pacific act oppositely while the decadal variability shows the horse saddle pattern.In this case it has an-influence on the individual ENSO'events by the superposition of the decadal variability.  相似文献   

A DIAGNOSIS OF THE INTERANNUAL VARIABILITY OF SEA SURFACE TEMPERATURE AND SURFACE WIND FIELD IN THE TROPICAL OCEANS AND ITS CORRELATIVE CHARACTERS WITH ENSO CYCLE^*          下载免费PDF全文

YIN Yonghong  SHI Li  NI Yunqi 《Acta Meteorologica Sinica》2002,16(1):21-36

Utilizing the NCEP/NCAR reanalysis monthly datasets,and based on the filter and standard deviation calculation,the interannual variability of sea surface temperature (SST) and 1000 hPa wind field for the tropical Pacific,Indian and Atlantic Oceans is investigated for the past 20 years (1979-1998).The characters of space-time evolution in SST anomalies (SSTA) for each ocean and corresponding wind anomaly field are acquired by using rotated principal component (RPC) and linear regression analysis methods.Using the method of correlation analysis.the characters of three tropical oceans correlated with ENSO are investigated.The contemporary correlation between the SSTA in the Indian Ocean and in the equatorial eastern Pacific is positive,and there is a weak negative correlation between the SSTA in the equatorial east Atlantic Ocean and in the equatorial eastern Pacific.The lead-lag correlation analysis indicates that the SSTA in the equatorial Indian Ocean lags the dominant Pacific ENSO mode by 3 months,and the SSTA in the equatorial Atlantic Ocean leads ENSO mode by 6 months.The ENSO-correlated components in tropical Indian Ocean and tropical Atlantic Ocean display much the same amount of total variance in each ocean,i.e..14% in the Indian Ocean and 12% in the Atlantic Ocean and the maximums are all above 40%.  相似文献   

DYNAMICAL STUDY OF DIABATIC HEATING INFLUENCE ON RADIAL INHOMOGENEOUS STRUCTURE OF TROPICAL CYCLONE^*          下载免费PDF全文

LEI Xiaotu  CHEN Lianshou 《Acta Meteorologica Sinica》2002,16(1):86-93

Based on the tropical cyclone (TC) asymmetric disturbance as the superposition of the symmetric environmental circulation,the analytical solution of travelling wave is given by using the barotropical nondivergent model with diabatic heating forcing and non-friction in a plane polar coordinate.Then,the TC radial inhomogeneous structure is analyzed on radial/tangential velocity and geopotential height.It is found that the different kinds of structures are influenced by the Coriolis parameter (f),TC intensity (Ω),disturbance circular frequency (ω),and TC angular wavenumber (m).And,the diabatic heating (Q₁) has significant impacts on the radial/tangential velocity distribution shaped like the inner-tight and outer-relaxed.  相似文献   

1,7月东亚大陆低空高低压的天气气候学分析     

许宝玉  罗四维 《高原气象》1993,12(1):56-66

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海面温度对热带气旋路径的影响初探     

刘瑞云 《气象》1993,19(7):35-37

利用NOAA卫星AVHRR的3个红外通道的探测资料推算的海面温度场,分析了海面温度对热带气旋路径的影响,其结果是在127段热带气旋路径中有100段路径偏向暖海水区。  相似文献   

登陆北上影响山东的9216号强热带风暴   总被引：3，自引：1，他引：3  

张少林  顾润源 《气象》1993,19(10):29-32

对北上影响山东造成重大灾害的９２１６号强热带风暴进行了分析。涡度诊断分析和能量场分析表明，该热带风暴低压一直沿着正涡度中心及高能轴方向移动。暴雨中心集中在高能舌顶热附近，并与正涡度中心相一致。  相似文献   

用增强显示云图确定热带气旋强度的方法   总被引：3，自引：3，他引：3       下载免费PDF全文

李修芳  范蕙君 《应用气象学报》1993,4(3):362-369

文章介绍了用增强显示红外云图确定热带气旋强度的方法。利用1983—1988年GMS增强显示云图资料，对中央气象台使用的《用地球同步气象卫星红外云图估计热带气旋强度》的方法中的云特征指数进行了修改与调整，增加了眼区的温度、中心强对流云区和螺旋云带的云顶温度等新的云特征因子。经统计、拟合，得到云特征指数与热带气旋中心附近最大风速、最低海平面气压的对应关系，给出了计算热带气旋强度的人-机交互方法流程，此方法对各种强度的热带气旋都能客观地计算其强度，使用简便，且精度满足业务应用要求。  相似文献   

东亚寒潮活动对下游爆发性气旋生成的影响   总被引：3，自引：2，他引：3       下载免费PDF全文

孙淑清  高守亭 《气象学报》1993,51(3):304-314

本文研究了东亚寒潮过程与下游爆发性气旋之间的关系。通过对一个强寒潮过程及随后在西北太平洋上爆发性气旋生成的个例分析发现,寒潮过程相伴随的大环流调整给下游气旋猛烈发展提供了极好的背景条件。当超长波槽与长波槽耦合加深时,槽前气旋迅速发展。大槽的加深使高空急流不断加速,大风区向低层扩展。出口区的次级环流也随着急流的加强而加强,它促使北侧低层气旋发展。对93次爆发性气旋作统计分析进一步证实了上述结论。绝大多数过程皆伴有上游的强冷高压活动。高压中心越强相应的爆发气旋也越强,甚至可以发生连续的爆发。绝大多数爆发性气旋发生在超长波槽前,强高空急流出口区的向极侧。  相似文献   

The catastrophic cyclone of April 1991: Its Impact on the economy of Bangladesh   总被引：1，自引：1，他引：1  

Gazi Md. Khalil 《Natural Hazards》1993,8(3):263-281

A very severe cyclonic storm with wind speeds of over 240 km/h struck the coastal areas of Bangladesh in the full moon night of 29 April 1991. The path of the eye, close to the shore, raised a storm surge of unusual height, reportedly more than 9 m above the mean sea level, which devastated the offshore islands and the mainland coast. The damage to the physical infrastructure of the port of Chittagong and adjoining industrial area has been colossal, and recovery will take years. Death tolls from the cyclone, storm surge and its aftermath exceeded 145 000 making it one of the world's major natural disasters of this century.This paper is concerned with examining the magnitude and intensity of the disaster. It analyses how the people of Bangladesh, and the environment in which they live, were affected by the cyclone. A brief account is presented of loss of life and of the damage suffered in various sectors, including agriculture, industry, and physical infrastructure.The paper lays emphasis on the need of building a sufficient number of multipurpose cyclone shelters in the disaster-prone coastal areas of Bangladesh. Adequate measures should be taken for evacuating people from vulnerable areas and putting them into these shelters in the event of a cyclonic storm. Simplification of the current cyclone warning system is recommended.The difficulties of providing relief to the survivors are discussed. And finally, the need for improvement of the communication infrastructure in the coastal areas is highlighted.  相似文献   

NUMERICAL STUDY OF OROGRAPHIC INFLUENCE ON LOW FREQUENCY OSCILLATION     

张勤  朱育峰  倪允琪  林武银 《热带气象学报(英文版)》1995,1(1):67-74

Orographic effects on monthly-and seasonal-scale low frequency oscillation are investiged in terms of a five-level global spectral model with a triangle truncation at wavenumber 10 that contains relatively full physical parameterization, followed by analysis and comparison of the lowpass filtered data separately obtained from models with and without orography. Results show that remarkable seasonal characteristics are displayed in the orographic forcing-generated low frequency wavetrain on monthly and seasonal scales. It is found that the Northern Hemisphere summer orography-produced tropical heating acts as source of the low-frequency wavetrain for both hemispheres. Besides, the simulations indicate that the orographic wavetrain perturbation can give rise to the anomaly in the equatorial zonal flow, whose transient forcing will cause a new wavetrain in the Southern Hemisphere, thus completing the cross-equatorial propagation of the northern wave in interhemispheric action.  相似文献