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中国东部地区降水季内变化的季节锁相 总被引:9,自引:1,他引:9
用1954-1983年5-8月的逐日降水资料分析了中国东部地区降水的气候特征,并讨论了它同东亚季风季节内变化的联系。结果发现,江淮梅雨同华南夏季风降水都具有季节锁相特征,前者呈单峰分布,后者呈双峰分布。同时,降水量的季内变化均具有20-25天的周期振荡特征。江淮流域降水的峰值和华南地区的第一个峰值主要受副热带季风影响,同夏季风的季节性北进和加强有关,华南地区第二个降水峰值受南海热带季风影响,与同期 相似文献
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1991年江淮梅雨期出现了三次暴雨过程,降水呈现显著的20-25天振荡,该周期明显短于海两期40天振荡的气候周期。分析表明,1991年梅雨降水的低频振荡与乌拉尔阻高、西太平洋副高、东亚与印度季风以及500hPa赤道地区向北传播涡列的20-25天振荡有着密切的关系。 相似文献
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利用有限区域细网格模式与T42L9谱模式进行三维嵌套,对1991年7月10-11日08时江淮梅雨暴雨过程作了数值模拟,探讨了低纬环流系统和由其形成的水汽输送通道对江淮梅雨的影响。结果表明:孟加拉湾水汽源地及其西南季风水汽输送通道的贡献大于南海水汽源地及其东南季风水汽输送通道;两个水汽源同时存在,对江淮梅雨暴雨引起非线性叠加增强;台风环流和季风低压环流强度的变化对江淮梅雨暴雨有重要作用。 相似文献
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文章分析了1991年江淮梅雨期间的东亚夏季风活动及其在梅雨期对流性暴雨形成中的作用。结果指出,第一场暴雨发生在夏季风暴发之前,它主要受副热带西风气流影响;后两场暴雨期间由于副高和东南季风稳定少动,西南季风的暴发和活动起了十分重要的作用,其进退演变导致了江淮梅雨的维持和中断。西南季风的一个重要作用是将热带地区(阿拉伯海及孟加拉湾)对流性很强的大气输送到江淮一带,由此使江淮流域在梅雨中后期形成了远强于一般年份的对流性降水,特别是第三场暴雨。文中通过定义低纬偏西风强度,讨论了强风带上强风速核的地域分布和传播特征。 相似文献
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近116年江淮梅雨异常及其环流特征分析 总被引:6,自引:3,他引:6
利用江淮地区1885—2000年近116a梅雨特征量资料和NCEP/NCAR逐日再分析资料,采用谐波分析、最大熵谱分析、小波分析、合成分析等方法讨论了江淮梅雨特征量的年际-年代际变化特征及梅雨异常的环流特征。结果表明;江淮梅雨特征量存在显著的年际和年代际变化特征。入梅日期、出梅日期、梅雨期长度呈显著上升的长期变化趋势,梅雨量和梅雨强度长期趋势变化不明显;梅雨特征量均存在多时间尺度的振荡周期,入梅日期具有准24a、准5a和准3a的显著周期;出梅日期具有准35a、准22a和准5a的显著周期;梅雨量具有准40a、准15a、准9a和准3a的显著周期。丰梅年南亚高压中心强度和西太平洋副热带高压增强。枯梅年则反之。 相似文献
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IMPACT OF ENSO ON VARIABILITY OF SUMMER MONSOON OVER ASIA AND SUMMER RAINFALL IN CHINA 总被引:2,自引:1,他引:1
In this paper, the variability of the Asian summer monsoon circulation during the ENSO period is diagnostically analyzed. Evidence suggests that every member of the Asian summer monsoon system change in varying degrees, even, oppositely, during El Nino and La Nina events. Then, the basis of the summer rainfall in east China analyzed using EOF, both region and extent of impact of the eastern tropical Pacific SSTA on the summer rainfall in East China are analyzed. This impact is closely related with development phase of the ENSO cycle, being most notable in the middle and lower reaches of the Yangtze and south of China. 相似文献
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THE EARLY SUMMER FLOOD PERIODS OF SOUTHERN CHINA AND THE SUMMER MONSOON CIRCULATION OF EAST ASIA 总被引:1,自引:0,他引:1
Based on the thermodynamic characteristics of the summer monsoon and foe change of the lower layer wind fields, the relation between the early summer flood periods of southern China, Including the first flood period of South China and the plum rains period of the middle-lower reaches of the Yangtze River and the activities of the summer monsoon is analysed.The establishment processes of the summer monsoon circulation of East Asia are investigated.It is shown that the beginning and ending of the flood periods are exactly in accordance with the arrival and departure of the fore boundary of the summer monsoon.The establishment process of the circulation from the very beginning of the arrival of the monsoon to the time of great prosperity of development are not the same for each year.They can be classified into four categories.Each category may have four or three stages.Besides, the structure of the summer monsoon regime of East Asia is not unitary.There exist four types of structure model of the monsoon regime of East Asia. 相似文献
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我国南方初夏汛期和东亚夏季风环流 总被引:12,自引:5,他引:12
主要根据低层夏季风热力学性质与流场演变特点深入讨论我国南方初夏汛期包括华南前汛期和长江中下游梅雨期同夏季风活动的联系,分析了东亚夏季风环流建立过程的阶段性和类型,指出汛期的开始与结束同夏季风前沿位置变动一致。我国夏季风从开始到发展鼎盛时期低纬大气环流的演变过程各年不完全相同,主要可归纳为4类,每类包括4个或3个不同阶段,从而可认识到东亚夏季风体系结构的非单一性,它可有4种结构模型,即仅是东南季风P的单气流型、强东南季风P与弱西南季风A的双气流型、强东南季风P和弱西南季风M的双气流型、强东南季风P和强(或弱)西南季风M以及弱西南季风A的3气流型。 相似文献
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Based on NCEP/NCAR daily reanalysis data, climate trend rate and other methods are used to quantitatively analyze the change trend of China's summer observed temperature in 1983—2012. Moreover, a dynamics-statistics-combined seasonal forecast method with optimal multi-factor portfolio is applied to analyze the impact of this trend on summer temperature forecast. The results show that: in the three decades, the summer temperature shows a clear upward trend under the condition of global warming, especially over South China, East China, Northeast China and Xinjiang Region, and the trend rate of national average summer temperature was 0.27℃ per decade. However, it is found that the current business model forecast(Coupled Global Climate Model) of National Climate Centre is unable to forecast summer warming trends in China, so that the post-processing forecast effect of dynamics-statistics-combined method is relatively poor. In this study, observed temperatures are processed first by removing linear fitting trend, and then adding it after forecast to offset the deficiency of model forecast indirectly. After test, ACC average value in the latest decade was 0.44 through dynamics-statistics-combined independent sample return forecast. The temporal correlation(TCC) between forecast and observed temperature was significantly improved compared with direct forecast results in most regions, and effectively improved the skill of the dynamics-statistics-combined forecast method in seasonal temperature forecast. 相似文献
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ENSO对亚洲夏季风异常和我国夏季降水的影响 总被引:21,自引:11,他引:21
首先对ENSO过程中亚洲夏季风环流的变化进行了诊断分析,结果表明在El Nino事件和LaNina事件中亚洲夏季风系统各成员均发生不同程度的变化,甚至出现相反的变异特征。其中,对我国东部地区夏季降水进行了EOF分析,并在此基础上分析了赤道太平洋SS-TA对我国东部地区夏季降水影响的区域和程度,该影响与ENSO循环的发展阶段密切相关,且在长江中下游地区和华南地区最为显著。 相似文献
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This paper investigates the diurnal variations of summer precipitation in Shanghai by using the city''s hourly precipitation data over a span of 35 years. The result shows that the precipitation peaks twice, in the morning and in the afternoon. Precipitation in the morning is characterized by light to moderate rain, and that in the afternoon by heavy to super heavy rain. The peak of short-duration precipitation is mostly found in the afternoon and at dusk, and that of long-duration precipitation in the morning. Most of the precipitation events in Shanghai are of a short duration of 2-3 hours. Basically, the precipitation is spatially distributed in three areas: the eastern coastal and central urban area, where the precipitation peaks mostly in the afternoon, the southern coastal area, where the precipitation peaks both in the afternoon and during the night, and the western area, where long-duration precipitation accounts for a much larger proportion than the other two areas. 相似文献
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1998年夏季中国南部低频降水特征与南海低频夏季风活动 总被引:15,自引:1,他引:14
1998年 5~ 8月 4 0°N以南的中国地区低频 (含准 4 5天、准 2 3天和准14天 )降水率及其方差占总降水率及其方差的比重很大 ,因此研究低频降水及与其相对应的低频环流对长江流域洪涝的影响是很重要的。研究表明 ,准 4 5天东西向低频槽脊由南海不断向北传播 ,以及低槽中的低频低涡向西传播是形成长江流域低频降水的重要原因 ,低频降水主要位于低频西风区 ,而低频槽南侧的低频西风实质是南海低频夏季风的表现 ,由此可见 ,南海低频夏季风的向北传播对长江流域降水具有重要贡献。 相似文献
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人工神经网络方法在夏季降水预报中的应用 总被引:11,自引:3,他引:8
在夏季雨型预报中引进了人工神经网络方法。首先,根据雨型与前期(冬季)环流和海温的关系,从前期冬季资料场中找预报因子;然后,用人工神经网络方法对我国夏季的雨型进行模拟预报,以前40年资料做训练样本,让网络在一定的学习规则下进行学习,最后得到一种分类预报模型。经对1992~1996年夏季雨型做独立试报,结果与实况基本相符。 相似文献
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ENSO对亚洲夏季风环流和中国夏季降水影响的诊断研究 总被引:26,自引:2,他引:24
文中以SVD分析技术为基础,发展了一种用以提取一个矢量场和一个标量场耦合信号的统计诊断方法——联合SVD方法(简记为CSVD),并运用CSVD分析了ENSO对亚洲季风环流系统及中国夏季降水的年际变化的影响。结果表明,在ElNino年,印度夏季风减弱,东亚夏季风增强;而在LaNina年,印度夏季风增强,东亚夏季风减弱。且ENSO对亚洲夏季风环流影响显著的区域主要在长江流域南北气流交汇区和索马里急流区,而对中国夏季降水影响最显著的区域则在江淮流域。 相似文献