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1.
印度与东亚夏季风环流对ENSO及其年代际异常响应的数值研究 总被引：3，自引：0，他引：3
根据诊断分析结果,利用LAGS改进的L9R15气候谱模式,设计了3个数值试验,讨论了不同的年代际背景下ENSO异常对亚洲夏季风环流的影响。研究表明不同背景的ENSO异常与亚洲夏季风活动存在密切的关系。在冷背景条件下,当ENSO处于发展时,印度夏季风偏弱,风速较小,降水量偏少。而东亚夏季风偏南气流较强,受低气压控制,有利于气流辐合,降水量偏多。在ENSO衰减期,印度夏季风仍偏弱,风速偏小,具有干旱的趋势,而东亚夏季风区大陆仍为低气压控制,风速略有减小,降水量比正常年多,而比ENSO前一年有减少的趋势。在暖背 相似文献
2.
利用Nio 3指数,把ENSO循环不同位相的夏季划分为四类并进行聚类分析,发现E1 Nio发展期和La Nia衰减期可以聚为一类;E1 Nio衰减期和La Nia发展期可以聚为一类。而后经过比较分析,考虑ENSO循环对江、淮地区降水的不同影响,定义了新的东亚副热带夏季风强度指数。并利用该指数研究了夏季风异常和ENSO循环与江、淮地区夏季降水年际变化的关系和成因。结果发现,ENSO年,淮河和长江中下游地区夏季降水的年际变化是ENSO和夏季风共同作用的结果。ENSO的不同位相对雨带的南北位置有重要影响,夏季风异常主要对雨量的偏多偏少起重要作用。而与ENSO无关的年份,易出现强夏季风,这种年份长江和淮河地区经常是一致的干旱。 相似文献
3.
《气象学报》2020,(典型暖)
利用通用地球系统模式开展的过去1500年气候模拟全强迫试验和对照试验结果,在验证模式模拟性能的基础上,采用多变量经验正交函数分解等方法,对比分析了典型暖期东亚夏季风年代际变化特征及其成因机制。结果表明,两个典型暖期东亚夏季风变化的主周期均为准10 a和准20 a。中世纪暖期黄河流域至日本南部一带降水偏多,长江流域以南和西北太平洋一带降水偏少;现代暖期东亚夏季风降水表现为"南涝北旱"型分布特征。内部变率是影响典型暖期东亚夏季风变化的主控因子之一,其中太平洋年代际振荡起决定性作用。当太平洋年代际振荡处于正位相时,热带西太平洋(东亚大陆)变暖(变冷),东亚地区海、陆热力差减小,对应弱的东亚夏季风。另外,中世纪暖期海平面气压的动态变化对应850 hPa风场在西北太平洋(日本海)一带均出现了经向排列的异常反气旋(气旋),从而导致中国南部(北部)降水偏多(偏少)。 相似文献
4.
耦合模式FGOALS_s 模拟的亚澳季风年际变率及ENSO 总被引：10，自引：7，他引：3
本文评估了中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室 (LASG/IAP) 新一代耦合气候模式FGOALS_s对亚澳季风和ENSO的模拟。结果表明, FGOALS_s可以模拟出亚澳季风的主要气候态特征。FGOALS_s模拟的ENSO事件振幅为观测值的70%, 同时它合理再现了ENSO周期的非规则性。FGOALS_s可以定性模拟出ENSO的主要空间特征。当赤道东太平洋SST升高时, 印度洋和西太平洋海表面气压升高, 而东太平洋海表面气压降低。FGOALS_s的主要缺陷在于模拟的ENSO峰值多出现在春季和夏季。与ENSO振幅偏小相反, FGOALS_s模拟的亚澳季风年际变率振幅大于观测。但是观测中亚澳季风年际变率与ENSO暖位相的显著负相关关系, 在模式中没有得到合理再现, 原因部分可归之于耦合模式在ENSO锁相模拟上的缺陷。由于模式模拟的ENSO峰值出现在北半球春季和夏季, Walker环流异常下沉支移动到西北太平洋, 其激发出的异常反气旋位置较之观测要偏东, 导致印度季风降水和El Niño的负相关关系不显著; 在北半球冬季, 由于模式中的赤道东太平洋SST暖异常较弱, 亚澳季风响应也偏弱。此外, 由于赤道东太平洋SST异常向西伸展, 观测中位于澳洲季风区的辐散中心向西偏移, 最终导致模式中澳洲季风降水与ENSO的负相关同样不显著。 相似文献
5.
本文通过与观测和再分析资料的对比,评估了LASG/IAP发展的气候系统模式FGOALS的两个版本FGOALS-g2和FGOALS-s2对南亚夏季风的气候态和年际变率的模拟能力,并使用水汽收支方程诊断,研究了造成降水模拟偏差的原因。结果表明,两个模式夏季气候态降水均在陆地季风槽内偏少,印度半岛附近海域偏多,在降水年循环中表现为夏季北侧辐合带北推范围不足。FGOALS-g2中赤道印度洋"东西型"海温偏差导致模拟的东赤道印度洋海上辐合带偏弱,而FGOALS-s2中印度洋"南北型"海温偏差导致模拟的海上辐合带偏向西南。水汽收支分析表明,两个模式中气候态夏季风降水的模拟偏差主要来自于整层积分的水汽通量,尤其是垂直动力平流项的模拟偏差。一方面,夏季阿拉伯海和孟加拉湾的海温偏冷而赤道西印度洋海温偏暖,造成向印度半岛的水汽输送偏少;另一方面,对流层温度偏冷,冷中心位于印度半岛北部对流层上层,同时季风槽内总云量偏少,云长波辐射效应偏弱,对流层经向温度梯度偏弱以及大气湿静力稳定度偏强引起的下沉异常造成陆地季风槽内降水偏少。在年际变率上,观测中南亚夏季风环流和降水指数与Ni?o3.4指数存在负相关关系,但FGOALS两个版本模式均存在较大偏差。两个模式中与ENSO暖事件相关的沃克环流异常下沉支和对应的负降水异常西移至赤道以南的热带中西印度洋,沿赤道非对称的加热异常令两个模式中越赤道环流季风增强,导致印度半岛南部产生正降水异常。ENSO相关的沃克环流异常下沉支及其对应的负降水异常偏西与两个模式对热带南印度洋气候态降水的模拟偏差有关。研究结果表明,若要提高FGOALS两个版本模式对南亚夏季风气候态模拟技巧,需减小耦合模式对印度洋海温、对流层温度及云的模拟偏差;若要提高南亚夏季风和ENSO相关性模拟技巧需要提高模式对热带印度洋气候态降水以及与ENSO相关的环流异常的模拟能力。 相似文献
6.
利用通用地球系统模式开展的过去1500年气候模拟全强迫试验和对照试验结果，在验证模式模拟性能的基础上，采用多变量经验正交函数分解等方法，对比分析了典型暖期东亚夏季风年代际变化特征及其成因机制。结果表明，两个典型暖期东亚夏季风变化的主周期均为准10 a和准20 a。中世纪暖期黄河流域至日本南部一带降水偏多，长江流域以南和西北太平洋一带降水偏少；现代暖期东亚夏季风降水表现为“南涝北旱”型分布特征。内部变率是影响典型暖期东亚夏季风变化的主控因子之一，其中太平洋年代际振荡起决定性作用。当太平洋年代际振荡处于正位相时，热带西太平洋（东亚大陆）变暖（变冷），东亚地区海、陆热力差减小，对应弱的东亚夏季风。另外，中世纪暖期海平面气压的动态变化对应850 hPa风场在西北太平洋（日本海）一带均出现了经向排列的异常反气旋（气旋），从而导致中国南部（北部）降水偏多（偏少）。 相似文献
7.
ENSO年东亚夏季风异常对中国江、淮流域夏季降水的影响 总被引：12，自引：2，他引：12
利用Nio3指数,把ENSO循环不同位相的夏季划分为4类并进行聚类分析,发现ElNio发展期和LaNia衰减期可以聚为一类,其夏季淮河流域降水往往偏多,长江中下游降水偏少;ElNio衰减期和LaNia发展期可以聚为一类,其夏季长江中下游地区降水往往偏多,淮河流域降水往往偏少。而后对这两大类中的年份分别聚类和合成分析。结果发现,这次聚类的结果反映了强弱夏季风对江、淮地区降水的影响。这一方面表明ENSO循环的同一位相既可能对应强东亚夏季风也可能对应弱夏季风,另一方面表明ENSO循环通过影响东亚夏季风环流异常的范围而使雨带位置发生变化,东亚夏季风强弱主要使雨量多少发生变化。 相似文献
8.
利用1905—2006年的太平洋年代际振荡(简称PDO)、ENSO和大连6—9月降水资料,分析三者之间的关系。结果表明:在PDO暖位相期,大连6—9月降水总体比常年偏少;PDO冷位相期,大连6—9月降水总体上比常年偏多;PDO与大连6—9月降水存在准周期对应关系,从PDO冷位相到暖位相,对应的大连6—9月降水距平8 a滑动平均曲线总体呈下降趋势。ENSO对大连6—9月降水的影响明显受PDO的调制,在PDO冷位相期,ENSO年大连6—9月降水总体上比常年偏多,而在PDO暖位相期,ENSO年大连6—9月降水总体上比常年偏少;不同强度和不同冷暖性质的ENSO,在不同PDO位相期内对大连6—9月降水的影响也各不相同。 相似文献
9.
对 140a历史资料的分析表明 :ELNino 南方涛动 (ENSO)与印度夏季风的反相关关系 (暖ENSO事件产生弱季风 )在近 10a来已经破坏了。有 2种可能原因。首先 ,与ENSO事件相关的瓦克环流向东南移可能导致了印度地区下沉气流减弱 ,因而有利于加强季风。另外 ,冬春季欧亚大陆地面温度升高———这是中纬度大陆变暖趋势的一部分 ,可能有利于加强陆地—海洋热力梯度 ,因而导致强季风的爆发。这就增加了这样一种可能性 :即近 1 0a来欧亚大陆变暖有助于维持正常水平的季风降水 ,尽管在这期间发生了强ENSO事件 相似文献
10.
K．KrishnaKumar BalajiRajagopalan MarkA．Cane 《辽宁气象》2000,(1):51-54
对140a历史资料的分析表明：EL Nino-南方涛动(ENSO)与印度夏季风的反相关关系(暖ENSO事件产生弱季风)在近10a来已经破坏了。有2种可能原因。首先,与ENSO事件相关的瓦克环流向东南移可能导致了印度地区下沉气流减弱,因而有利于加强季风。另外,冬春季欧亚大陆地面温度升高——这是中纬度大陆变暖趋势的一部分,可能有利于加强陆地—海洋热力梯度,因而导致强季风的爆发。这就增加了这样一种可能性：即近10a来欧亚大陆变暖有助于维持正常水平的季风降水,尽管在这期间发生了强ENSO事件。 相似文献
11.
The present study aims to (a) examine meteorological basis for construction of regional monsoon indices and (b) explore the commonality and differences among tropical regional monsoons, especially the teleconnection and monsoon–ENSO relationship. We show that the area-averaged summer precipitation intensity is generally a meaningful precipitation index for tropical monsoons because it represents very well both the amplitude of annual cycle and the leading mode of year-to-year rainfall variability with a nearly uniform spatial pattern. The regional monsoon circulation indices can be defined in a unified way (measuring monsoon trough vorticity) for seven tropical monsoon regions, viz.: Indian, Australian, western North Pacific, North and South American, and Northern and Southern African monsoons. The structures of the tropical monsoons are commonly characterized by a pair of upper-level double anticyclones residing in the subtropics of both hemispheres; notably the winter hemispheric anticyclone has a barotropic structure and is a passive response. Two types of upper-level teleconnection patterns are identified. One is a zonal wave train emanating from the double anticyclones downstream along the westerly jets in both hemispheres, including Indian, Northern African and Australian monsoons; the other is a meridional wave train emanating from the double anticyclones polewards, such as the South American and western North Pacific monsoons. Over the past 55 years all regional summer monsoons have non-stationary relationship with ENSO except the Australian monsoon. The regional monsoon–ENSO relationship is found to have common changing points in 1970s. The relationships were enhanced for the western North Pacific, Northern African, North American and South American summer monsoons, but weakened for the Indian summer monsoon (with a recovery in late 1990s). Regardless the large regional differences, the monsoon precipitations over land areas of all tropical monsoon regions are significantly correlated with the ENSO, suggesting that ENSO drives global tropical monsoon rainfall variability. These results provide useful guidance for monitoring sub-seasonal to seasonal variations of the regional monsoons currently done at NCEP and for assessment of the climate models’ performances in representing regional and global monsoon variability. 相似文献
12.
从短期气候预测关注的外强迫信号角度出发,回顾了国内外在海温异常对东亚夏季风和我国汛期降水影响机理方面的主要研究进展,重点评述了热带太平洋ENSO循环、热带印度洋全区一致型海温模态、热带印度洋海温异常偶极子、南印度洋偶极子和北大西洋海温三极子模态的年际变化及其对东亚夏季风年际变率的影响。从研究成果在短期气候预测业务中应用的角度,重点关注海温异常和东亚夏季风年际变率以及我国汛期降水多雨带位置的关系,总结了海温异常作为外强迫信号对我国汛期降水预测的指示意义以及汛期降水预测的难度。最后指出气候预测业务对东亚夏季风影响的机理研究和动力气候模式发展方面的需求。 相似文献
13.
Influence of ENSO and of the Indian Ocean Dipole on the Indian summer monsoon variability 总被引：1，自引：0，他引：1
Indian summer monsoon (ISM) variability is forced from external factors (like the El Niño Southern Oscillation, ENSO) but it contains also an internal component that tends to reduce its potential for predictability. Large-scale and local monsoon indices based on precipitation and atmospheric circulation parameters are used as a measure of ISM variability. In a 9-members ensemble of AMIP-type experiments (with same boundary SST forcing and different initial conditions) their potential predictability is comparable using both local and large-scale monsoon indices. In the sample analyzed, about half of more predictable monsoon years coincide with El Niño and/or positive Indian Ocean Dipole (IOD) events. Summer monsoon characteristics during ENSO and IOD years are analyzed through composites computed over a three years period (i.e. one year before and one year after the event peak) to investigate the mutual relationship between the events lagged in time. The connection between ISM and IOD is mostly confined in the summer and autumn, while that with ENSO is stronger and extends more in time. In the coupled model results the IOD influence on the monsoon is large, even because in the model IOD events are intense and easily reproduced due to a strong air-sea feedback in the eastern side of the basin. Monsoon seasons preceding or following an El Niño or a La Niña event are not exactly symmetric, even in terms of their biennial character. In most of the cases, both in reanalysis and model, El Niño and positive IOD events tend to co-occur with larger anomalies either in the Indo-Pacific ocean sector or over India, while La Niña and negative IOD do not. From the observed record, the ENSO-IOD correlation is positive strong and significant since mid-60s and it may correspond with either strong or weak ENSO-monsoon relationship and with strong or weak IOD-monsoon relationship. A main difference between those periods is the relationship between Indian monsoon rainfall and SST in other ocean basins rather than the Indo-Pacific sector alone. 相似文献
14.
Annalisa Bracco Fred Kucharski Franco Molteni Wilco Hazeleger Camiel Severijns 《Climate Dynamics》2007,28(5):441-460
This study investigates how accurately the interannual variability over the Indian Ocean basin and the relationship between the Indian summer monsoon and the El Niño Southern Oscillation (ENSO) can be simulated by different modelling strategies. With a hierarchy of models, from an atmospherical general circulation model (AGCM) forced by observed SST, to a coupled model with the ocean component limited to the tropical Pacific and Indian Oceans, the role of heat fluxes and of interactive coupling is analyzed. Whenever sea surface temperature anomalies in the Indian basin are created by the coupled model, the inverse relationship between the ENSO index and the Indian summer monsoon rainfall is recovered, and it is preserved if the atmospherical model is forced by the SSTs created by the coupled model. If the ocean model domain is limited to the Indian Ocean, changes in the Walker circulation over the Pacific during El-Niño years induce a decrease of rainfall over the Indian subcontinent. However, the observed correlation between ENSO and the Indian Ocean zonal mode (IOZM) is not properly modelled and the two indices are not significantly correlated, independently on season. Whenever the ocean domain extends to the Pacific, and ENSO can impact both the atmospheric circulation and the ocean subsurface in the equatorial Eastern Indian Ocean, modelled precipitation patterns associated both to ENSO and to the IOZM closely resemble the observations. 相似文献
15.
S. D. Bansod 《Theoretical and Applied Climatology》2005,82(3-4):143-152
Summary In this study the relationship between mid-tropospheric geopotential heights over the Northern Hemisphere (20° N to 90° N, around the globe) and Indian summer monsoon rainfall (ISMR: June to September total rainfall) have been examined. For this purpose, the monthly 500 hPa geopotential heights in a 2.5° lat./lon. grid over the Northern Hemisphere and the ISMR data for the period 1958 to 2003 have been used.The analysis demonstrates a dipole structure in the correlation pattern over the East Pacific Ocean in the month of January which intensifies in February and weakens in March.The average 500 hPa geopotential height over the eastern tropical Pacific Ocean during February (index one), has a significant positive relationship (r = 0.72) with the ISMR. In addition, the surface air temperature (SAT) anomaly over North-west Eurasia during January (index two) is found to be strongly related with the subsequent summer monsoon rainfall. These relationships are found to be consistent and robust during the period of analysis and these indices are found to be independent of each other.Hence, using index one and index two, a multiple linear regression model is developed for the prediction of the ISMR and the empirical relationships are verified on independent data. The forecast of the ISMR, using the above model, is found to be satisfactory.The dipole structure in the correlation pattern over the East Pacific region during February weakens once the ENSO (El-Nino and Southern Oscillation) events are excluded from the analysis. This suggests that the dipole type relationship between mid-tropospheric geopotential heights over the East Pacific Ocean and the ISMR may be a manifestation of the ENSO cycle. 相似文献
16.
基于旋转经验正交函数分解 (REOF) 方法探讨淮河流域1961—2010年夏季降水与厄尔尼诺/南方涛动 (ENSO)、北大西洋涛动 (NAO)、印度洋偶极子 (IOD)、太平洋年代际振荡 (PDO) 之间的关系,并进一步分析各气候因子不同位相单独以及联合对淮河流域夏季降水的影响。结果表明:淮河流域夏季降水与ENSO,PDO,NAO,IOD等气候因子具有较稳定的相关性,其中,PDO和IOD是影响淮河流域夏季降水的关键因子,且PDO与夏季降水呈显著负相关关系;各气候因子的冷暖位相单独及联合对淮河流域夏季降水的影响不同,PDO的冷期以及NAO,IOD冷位相使流域北部的夏季降水量呈显著增加趋势,PDO分别联合ENSO,NAO和IOD的冷、暖位相对流域北部地区和淮河上游地区的夏季降水影响显著。 相似文献
17.
Summary In this paper, we have tried to understand the ENSO, MJO and Indian summer monsoon rainfall relationships from observation as well as from coupled model results. It was the general feeling that El-Niño years are the deficient in Indian monsoon rainfall and converse being the case for the La-Niña years. Recent papers by several authors noted the failure of this relationship. We find that the model output does confirm a breakdown of this relationship. In this study we have seen that a statistically defined modified Indian summer monsoon rainfall (MISMR) index, a linearly regressed ISMR index and dynamical Webster index (WBSI), shows an inverse relationship with ENSO index during the entire period of integration (1987 to 1999). It is also seen from this study that the amplification of the MJO signals were large and the ENSO signals were less pronounced during the years of above normal ISMR. The MJO signal amplitudes were small and ENSO signals were strong during the years of deficient ISMR. It has been noted that here is a time lag between the MJO and ENSO signal in terms of their modulation aspect. If time lag is added with the ENSO signal then both signals maintain the amplitude modulation theory. A hypothesis is being proposed here to define a relationship between MJO and ENSO signals for the entire period between 1987 and 1999.Received September 18, 2002; revised November 22, 2002; accepted December 20, 2002
Published online: May 8, 2003 相似文献
18.
ENSO及其年代际异常对中国东部气候异常影响的观测分析 总被引：24，自引：3，他引：21
朱乾根 《南京气象学院学报》1998,21(4):615-623
在不同的ＳＳＴ年代际背景下,东亚季风和ＥＮＳＯ事件的关系是不同的。中国东部降水异常在冷态和暖态下,不是简单的线性反相关关系。在冷态时,最大的正距平中心发生在第二年早夏的长江以南地区;在暖态时,发生在第二年冬春季的华南地区。气温变化与降水变化并不对应,高温高湿的相关性不明显。不同的年代际海温背景使海气交换发生变换,改变了海陆热力对比,从而改变了海陆气压差,也就改变了季风的强度,使ＥＮＳＯ和东亚季风的 相似文献
19.
东亚季风环流演变的主要模态及其与中国东部降水异常的联系 总被引：2，自引：0，他引：2
利用美国国家环境预报中心和国家大气研究中心(NCEP/NCAR)再分析环流资料、美国国家海洋和大气管理局(NOAA)重构的海温资料和中国国家气象信息中心(NMIC)整理的752个测站降水资料,对东亚地区季风环流季节演变主要模态及其与中国东部降水异常的关系进行了分析。结果表明,东亚地区850hPa季风环流季节演变存在两个主要模态,第一模态主要受热带印度洋海温和赤道东太平洋海温偏低背景下印度洋偶极(IOD)演变过程控制;第二模态主要受赤道东太平洋ENSO循环和IOD演变控制。对应第一模态,夏季华北多雨,长江流域少雨;对应第二模态,夏季华北、长江流域多雨,淮河、华南少雨。近50年两模态发生了明显改变,与降水变化有很好的对应关系。 相似文献
20.
利用地球系统模式（CESM）开展过去2000 年气候模拟试验,在利用观测资料、再分析资料对模拟资料进行检验的基础上,探讨百年时间尺度上亚澳夏季风降水的时、空变化特征及其成因,对于认识百年尺度气候变化规律、定量区分自然因子和人类活动对亚澳夏季风的影响具有重要意义。结果表明:过去2000 年亚澳夏季风降水和温度的波动较为一致,暖期降水多,冷期降水少。两者相关系数为0.83,达到99%置信度。此外,亚澳夏季风降水存在105、130、180 a的百年尺度周期。亚澳夏季风降水经验正交函数分解第一模态在印度洋北部呈南北反向的分布型态,在东亚地区呈负、正、负的分布型态;第二模态在印度洋北部呈正、负、正的分布型态,在东亚地区呈全区一致型的分布型态。经验正交函数分解第一特征向量和第二特征向量的正、负值中心大多出现在印度洋北部地区,南北呈不对称分布。亚澳夏季风降水的105 a周期主要受火山活动和土地利用/覆盖的影响,130 a周期主要受太阳辐射、气候系统内部变率的影响,180 a周期主要受火山活动的影响。从经验正交函数分解第一特征向量来看,整个亚澳夏季风降水主要受土地利用/覆盖、太阳辐射的影响;第二特征向量表明亚澳夏季风降水在百年际空间变化上主要受太阳辐射和气候系统内部变率的影响;第三特征向量表明亚澳夏季风降水在百年际空间变化上主要受气候系统内部变率和温室气体的影响。该研究对揭示百年际时间尺度气候变化特征、辨识影响气候变化的自然因素与人为因素、理解其影响气候的物理机制等具有重要意义,也为应对该区域气候变化提供了参考依据。 相似文献