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1.
TBO的原因－异常东亚冬季风与ENSO循环的相互作用 总被引：21，自引：3，他引：21
基于对 ＮＣＥＰ／ ＮＣＡＲ再分析资料以及其他资料（ＯＬＲ，降水和气温等）的分析研究，结果表明东亚和西北太平洋地区的对流层环流和气候变化都有明显的准两年振荡（ＴＢＯ）特征。同时，异常东亚冬季风可以影响次年夏季的大气环流和气候变化，特别是在东亚地区；而异常东亚冬季风和ＥＮＳＯ循环间又有明显相互作用：持续的强（弱）东亚冬季风通过海─气相互作用可以激发 Ｅｌ Ｎｉ ｏ（Ｌａ Ｎｉ ａ）， Ｅｌ Ｎｉ ｏ（Ｌａ Ｎｉ ａ）反过来又可通过遥相关或遥响应而导致东亚冬季风偏弱（强）。强或弱的冬季风和ＥＮＳＯ循环是相互衔接在一起的，因此可以认为异常东亚冬季风与ＥＮＳＯ循环的相互作用是ＴＢＯ对流层准两年振荡）的基本原因。 相似文献
2.
中国西北夏季降水的EOF分析及其与500hPa高度场的关系 总被引：12，自引：8，他引：12
本利用我国１１０°Ｅ以西的１４０个台站７－９月月降水量及５００ｈＰａ１０°×５°网格点资料（１９６０－１９９０年），与７－９月月降水量分别进行ＥＯＦ分解，并与５００ｈＰａ高度场进行了对比。结果发现：７－９月月降水量第一特征向量在青藏高原东北侧有一高值中心，该中心与有关学计算的信噪比高值中心和准３年周期显的区域一致（均指降水量）；７－８月月降水量第一特征向量与５００ｈＰａ高度场在２０°－４０° 相似文献
3.
强弱南海夏季风活动及大气季节内振荡 总被引：26，自引：0，他引：26
应用ＮＣＥＰ再分析资料和中国降水资料，分析研究了对应南海强、弱夏季风的环流形势及其与之相应的中国东部的降水异常。其结果表明，由强、弱夏季风所引起的中国气候异常是完全不同（甚至反相）的。分析大气季节内振荡（ＩＳＯ）的活动还表明，对应大气强（弱）南海夏季风，南海地区 ８５０ ｈＰａ也有强（弱）大气 ＩＳＯ；而强、弱南海夏季风环流（２００ ｈＰａ和 ８５０ ｈＰａ）主要由异常的大气ＩＳＯ所激发。本研究还揭示了南海地区大气ＩＳＯ的变化往往与江淮地区大气ＩＳＯ的变化反相，例如南海地区的强（弱）大气ＩＳＯ常与江淮流域的弱（强）大气ＩＳＯ相对应。对于大气ＩＳＯ的强度，一般多表现出局地激发特征，经向传播相对较弱。 相似文献
4.
南海和印度洋海温异常对东亚大气环流及降水的影响 总被引：38，自引：11，他引：27
利用英国气象局全球海温资料和ＮＣＥＰ再分析资料以及我国１６０个标准站降水资料,进行合成分析和ＳＶＤ分析。结果表明,当南海、孟加拉湾和阿拉伯海春季（３～５月）海温为一致正（负）异常时,夏季（６～８月）副高偏南（北）偏西（东）偏强（弱）,我国长江流域降水偏多（少）,华南和华北降水偏少（多）。 相似文献
5.
南海暖池的季节和年际变化及其与南海季风爆发的关系 总被引：16，自引：3，他引：16
用ＬＥＶＩＴＵＳ和ＮＣＥＰ／ＮＣＡＲ ＯＩＳＳＴ资料,分析了南海暖池的季节和变化特征及其与西太平洋暖池和印度洋暖池的关系,讨论了南海暖池强度指数的年际变化与南海季风爆发时间的联系,结果指出,南海暖池有明显的季节变化牲,１２～２月隆冬季节最弱,３～４月迅速发展北上,６～９月达其盛期,整个南海均为高于２８℃的暖水,１０～１１月迅速减弱南退：在南海暖池盛期,整个南海均为高于２８℃的暖水最大厚度达５５ｍ, 相似文献
6.
用主振荡型（ Ｐ Ｏ Ｐ）方法分析了热带洋区月平均海表温度异常（ Ｓ Ｓ Ｔ Ａ）。结果表明,最重要的 ４ 个传播型 Ｐ Ｏ Ｐ对与 Ｅｌ Ｎｉｎｏ／ Ｌａ Ｎｉｎａ 事件关系密切,说明这类事件具有复杂的时空结构。在此基础上,给出了一个能定量地综合多个传播型 Ｐ Ｏ Ｐ对作用的 Ｐ Ｏ Ｐ中性预测方案。非独立样本和独立样本试验表明,它具有 ４ 个月的预测时效,且其预测能力在 Ｓ Ｓ Ｔ 强异常的 Ｅｌ Ｎｉｎｏ、 Ｌａ Ｎｉｎａ 事件阶段强于弱异常的非 Ｅｌ Ｎｉｎｏ／ Ｌａ Ｎｉｎａ 事件阶段。 相似文献
7.
利用热带太平洋海气耦合异常模式的３０ａ模拟结果，对模式ＥＮＳＯ的变化性及多重时间尺度过程进行了细致分析，建立了一ＥＮＳＯ循环多重时间尺度过程相互作用的非线性相似（Ａｎａｌｏｇ）模型，并提出了ＥＮＳＯ循环主周期形成的一种可能机制。指出：和观测事实类似，模式ＥＮＳＯ过程确实涉及到三种时间尺度，即３—４ａ主周期振荡（ＬＦ）、准两年振荡（ＱＢ）和年循环（ＡＣ）；其中，ＱＢ过程是线性海气耦合系统的本征模态，年循环（ＡＣ）对其形成没有本质的影响；３—４ａ主周期振荡（ＬＦ）是一非线性系统的自激振荡现象，其形成是线性系统的本征模即ＱＢ过程通过非线性机制尤其是通过大气辐合反馈加热的“单向性”过程在ＱＢ的暖态产生的减频增幅所致；平均年循环（ＡＣ）虽然不能对ＥＮＳＯ循环形成有本质影响，但它可明显影响ＥＮＳＯ循环的具体振幅和位相，使得ＥＮＳＯ循环具有明显的不规则性并对季节循环具有明显的“锁相”特征；ＥＮＳＯ变化性确是ＬＦ、ＱＢ以及ＡＣ多重时间尺度相互作用形成的。本文提出的ＥＮＳＯ循环时间尺度选择机制不仅解释了主周期振荡的形成过程，而且也较好地解释了ＥＮＳＯ变化的谱，因此，这一机制更接近于观测事实。 相似文献
8.
欧亚500 hPa环流、雪盖和中国降水量3—4年耦合振荡 总被引：1，自引：0，他引：1
用２２年（１９７３～１９９４年）观测资料,由循环主振荡型分析（ＣＳＰＯＰ）揭示了东半球５００ｈＰａ环流、雪盖和中国降水量耦合系统的３～４年振荡的循环过程。结果表明,环流－冰雪－降水系统耦合振荡（ＡＳＲＯ）存在显著的欧亚太平洋（ＥＵＰ）和中国东部型（ＥＣ）耦合移动波列,其中５００ｈＰａ高度与雪盖波列空间位相相反,但一致向东南方向移动,而中国降水波列由北向南传播。这反映出欧亚雪盖异常影响欧亚大陆和海洋加热对比,并通过大气内部动力过程激发的耦合空间波的能量频散途径。 相似文献
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11.
Interannual heat content variability in the South China Sea and its response to ENSO 总被引：2，自引：0，他引：2
The interannual variability of upper ocean heat content (OHC) in the South China Sea (SCS) for the period of 1987–2006 and its response to ENSO events are investigated. It is found that the variability has a good correspondence with ENSO events, but with opposite phase. Negative OHC anomalies appear during ENSO warm phases, while positive OHC anomalies occur during ENSO cool phases. In addition, negative (positive) OHC anomalies propagate westward obviously during ENSO warm (cool) phases in the northern SCS. In contrast, OHC anomalies in the southern SCS do not exhibit distinct westward propagation during ENSO events. To explore why the OHC anomalies cannot propagate westward in the southern SCS, the interannual variability of oceanic and atmospheric anomaly fields including wind stress curl (WSC), horizontal wind stress, latent heat flux (LHF) and sea level pressure (SLP) is investigated. The results show that after a mature phase of ENSO warm (cool) event, negative (positive) OHC anomalies first appear in the northern SCS, which comes from the western Pacific through Luzon Strait. Then cyclonic (anticyclonic) wind stress anomalies occur in the northern SCS, which leads to positive (negative) WSC anomalies. Meanwhile, positive (negative) LHF anomalies which correspond to oceanic heat loss (gain) occur in this region. The effects of WSC and LHF, combined with the westward propagating negative (positive) OHC anomalies from the western Pacific, may contribute to rapid growth and propagation of the OHC anomalies in the northern SCS. On the contrary, the negative (positive) WSC and LHF anomalies associated with positive (negative) SLP in the southern SCS seem to be the important processes responsible for the weakening and non-propagation of the OHC anomalies in the southern SCS after a mature phase of ENSO warm (cool) event. 相似文献
12.
Prior studies have revealed that,as a part of the Pacific tropical gyre,the South China Sea throughflow(SCSTF) is strongly influenced by the Pacific low-latitude western boundary current(LLWBC).In this study,ocean general circulation model(OGCM) experiments with and without connection to the South China Sea(SCS) were performed to investigate the impact of the SCSTF on the Pacific LLWBC.These model experiments show that if the SCS is blocked,seasonal variability of the Kuroshio and Mindanao Current becomes stronger,and the meridional migration of the North Equatorial Current(NEC) bifurcation latitude is enhanced.Both in seasonal and interannual time scales,stronger Luzon Strait transport(LST) induces a stronger Kuroshio transport combined with a southward shift of the NEC bifurcation,which is unfavorable for a further increase of the LST;a weaker LST induces a weaker Kuroshio transport and a northward shifting NEC bifurcation,which is also unfavorable for the continuous decrease of the LST. 相似文献
13.
The present study investigates the influence of South China Sea (SCS) SST
and ENSO on winter (January--February--March; JFM) rainfall over South China
and its dynamic processes by using station observations for the period
1951--2003, Met Office Hadley Center SST data for the period 1900--2008, and
ERA-40 reanalysis data for the period 1958--2002. It is found that JFM
rainfall over South China has a significant correlation with Nino-3 and
SCS SST. Analyses show that in El Nino or positive SCS SST anomaly
years, southwesterly anomalies at 700 hPa dominate over the South China Sea,
which in turn transports more moisture into South China and favors increased
rainfall. A partial regression analysis indicates that the independent ENSO
influence on winter rainfall occurs mainly over South China,
whereas SCS SST has a larger independent influence on winter rainfall in
northern part of South China. The temperature over South China shows an obvious decrease at
300 hPa and an increase near the surface, with the former induced by
Nino-3 and the latter SCS SST anomalies. This enhances the convective
instability and weakens the potential vorticity (PV), which explains the
strengthening of ascending motion and the increase of JFM rainfall over
South China. 相似文献
14.
This study investigates the structure and propagation of intraseasonal sea surface temperature(SST) variability in the South China Sea(SCS) on the 30–60-day timescale during boreal summer(May–September). TRMM-based SST, GODAS oceanic reanalysis and ERA-Interim atmospheric reanalysis datasets from 1998 to 2013 are used to examine quantitatively the atmospheric thermodynamic and oceanic dynamic mechanisms responsible for its formation. Power spectra show that the 30–60-day SST variability is predominant, accounting for 60% of the variance of the 10–90-day variability over most of the SCS. Composite analyses demonstrate that the 30–60-day SST variability is characterized by the alternate occurrence of basin-wide positive and negative SST anomalies in the SCS, with positive(negative) SST anomalies accompanied by anomalous northeasterlies(southwesterlies). The transition and expansion of SST anomalies are driven by the monsoonal trough–ridge seesaw pattern that migrates northward from the equator to the northern SCS. Quantitative diagnosis of the composite mixed-layer heat budgets shows that, within a strong 30–60-day cycle, the atmospheric thermal forcing is indeed a dominant factor, with the mixed-layer net heat flux(MNHF) contributing around 60% of the total SST tendency, while vertical entrainment contributes more than 30%. However, the entrainment-induced SST tendency is sometimes as large as the MNHF-induced component, implying that ocean processes are sometimes as important as surface fluxes in generating the30–60-day SST variability in the SCS. 相似文献
15.
Influence of sea surface temperature on the intraseasonal variability of the South China Sea summer monsoon 总被引：6，自引：4，他引：2
The objective of this study is to examine, based on recently available high resolution satellite and observational data, the evolution and role of sea surface temperature (SST) in influencing the intraseasonal variability of the South China Sea (SCS) summer monsoon (SM). The study focuses on the 30–60?day timescale when the northward propagating anomalies are dominant over the SCS. Composite analysis of the SST maximum events during SCS SM shows that increased SST anomalies over the SCS are significantly influenced by the downward shortwave radiation flux anomalies, with the suppressed surface latent heat flux anomalies supplementing to it. A thermal damping of the positive SST anomalies induces positive upward heat fluxes, which then destabilize the lower atmosphere between 1,000 and 700?hPa. The positive SST anomalies lead the positive precipitation anomalies over the SCS by 10?days, with a significant correlation (r?=?0.44) between the SST-precipitation anomalies. The new findings here indicate an ocean-to-atmosphere effect over the SCS, where underlying SST anomalies tend to form a favorable condition for convective activity and sustain enhanced precipitation during the SCS SM. It is also argued, based on our observations, that the negative sea level pressure anomalies induced by the positive SST anomalies play a role in enhancing the northward propagation of the intraseasonal anomalies over the SCS. 相似文献
16.
西北太平洋与南海热带气旋活动季节变化的差异及可能原因 总被引：1，自引：0，他引：1
利用1945~2011年美国联合台风预警中心(JTWC)西北太平洋热带气旋资料,研究了南海(5°N~25°N,110°E~120°E)与西北太平洋(5°N~25°N,120°E~180°)热带气旋生成位置、生成频数、强度和持续时间的季节变化差异及其成因。从热带气旋路径穿越经度带频数的角度,探讨了ENSO对气旋活动年际变化的影响。结果表明,南海热带气旋活动显著地受季风调控。在南海冬季风作用下,1~4月热带气旋生成于10°N以南且频数较少、强度较弱,这主要是低层气旋式相对涡度和弱东风切变区偏南造成的。相反,受夏季风影响,6~9月是热带气旋生成最多、最频繁的季节,大都生成于南海北部17°N附近。在5月(10月)的季节转换期,生成位置大幅度北进(南撤)且生成频数显著增加(减少),取决于风速垂直切变及中层的相对湿度的急剧转变。11、12月两海域热带气旋生成于10°N以南主要归因于其上空中层大气相对湿度较北部偏大。在西北太平洋,热带气旋生成的季节变化没有南海显著,只在7月有一次明显的变化,7~10月是热带气旋活动的"盛期"。在强度上,西北太平洋大部分区域全年均为弱东风切变,因此热带气旋以台风为主且持续时间长;但南海多为热带风暴。ENSO事件使得不同季节热带气旋生成区域和气旋路径地理位置发生显著变化。在El Nio事件期间,穿越南海所在经度带路径频数为负距平,而西北太平洋经度带为正距平;在La Nia事件期间,情况相反。 相似文献
17.
利用1951～2005年华南地区3月份的降水资料、NOAA海温资料、Ni?o3.4指数和NCEP再分析资料,分析了华南3月份降水异常与同期环流场、全球海温场的关系,从环流和海温的角度揭示了华南3月份降水异常的可能原因。结果表明,当华南3月份降水偏多(少)时,在对流层中低层,北太平洋海区存在气旋(反气旋)性环流异常,西太平洋及南海海面上存在反气旋(气旋)性环流异常,这样的环流异常有利(不利)于东南暖湿气流与北方东部异常冷空气在华南地区形成水汽辐合,导致降水显著增多(减少)。进一步的分析表明,ENSO和北印度洋及南海附近海温是影响华南3月份降水异常的重要外强迫因子,ENSO对华南3月降水异常的影响是通过影响春季西太平洋副热带高压和低层风场异常实现的,而北印度洋及南海附近海温对华南3月降水异常的影响则是通过垂直环流场异常和低层风场以及西太平洋副热带高压异常来实现的。 相似文献
18.
The present study evaluates the precipitation variability over the South China Sea (SCS) and its relationship to tropical Indo-Pacific SST anomalies during spring-to-summer transition (April-May-June, AMJ) simulated by 23 Intergovernmental Panel on Climate Change Coupled Model Intercomparison Project Phase 5 coupled models. Most of the models have the capacity to capture the AMJ precipitation variability in the SCS. The precipitation and SST anomaly (SSTA) distribution in the SCS, tropical Pacific Ocean (TPO), and tropical Indian Ocean (TIO) domains is evaluated based on the pattern correlation coefficients between model simulations and observations. The analysis leads to several points of note. First, the performance of the SCS precipitation anomaly pattern in AMJ is model dependent. Second, the SSTA pattern in the TPO and TIO is important for capturing the AMJ SCS precipitation variability. Third, a realistic simulation of the western equatorial Pacific (WEP) and local SST impacts is necessary for reproducing the AMJ SCS precipitation variability in some models. Fourth, the overly strong WEP SST impacts may disrupt the relationship between the SCS precipitation and the TPO-TIO SST. Further work remains to be conducted to unravel the specific reasons for the discrepancies between models and observations in various aspects. 相似文献
19.
Interannual and Interdecadal Variations in Heat Content of the Upper Ocean of the South China Sea 总被引：2，自引：0，他引：2
The vertically averaged temperature (TAV) from surface to 100 m depth of the South China Sea for the period 1959-1988 is analyzed. The results indicate that there is a significant long-term variability from interannual to interdecadal scales in the heat content in the upper ocean. The heat content of the upper ocean of the South China Sea increases evidently in the El Nino year. TAV anomaly in the ocean was negative from the end of 1950’s to early l970’s, and then changed to positive. The changes of TAV of the ocean are closely related to ENSO events, the Asian winter monsoon and the tropical atmospheric circulation anomalies. 相似文献
20.
Implication of the South China Sea Throughflow for the Interannual Variability of the Regional Upper-Ocean Heat Content 总被引：2，自引：0，他引：2
In this study the interannual variability of the upper-ocean heat content in the South China Sea (SCS) was revisited using simple ocean data assimilation (SODA) combined with objective analyzed data sets that included the horizontal and vertical structures.The results confirmed that the upper-ocean heat content in the SCS is lower than normal during the mature phase of El Nin o events,and two super El Nin o events,1982/1983 and 1997/1998 were also included.The variability of the heat content was consistent with the variability of the dynamic height anomalies.The SCS throughflow (SCSTF) plays an important role in regulating the interannual variability of the heat content,especially during the mature phase of El Nin o events. 相似文献