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1.
By prescribing sea surface temperature anomalies(SSTAs)over eastern equatorial Pacific inJanuary—March,the lag influence of ENSO(El Nino and La Nina)on monsoon over East Asiahas been studied.The results suggest that,due to the excitation of atmospheric low-frequencyoscillation by the SSTA,ENSO has significant lag influence on the monsoon over East Asia.During the summer after E1 Nino,the subtropical high over western Pacific is intensified andshows the northward and westward displacement,meanwhile,the rainfall over East China isbelow normal,especially in North China:during the winter after E1 Nino,both the Asian troughand the winter monsoon over East Asia are strengthened.During the summer after La Nina,theanomalous subtropical high prevails over the lower reaches of Yangtze(Changjiang)River,therainfall between Yangtze and Huaihe Rivers is below normal:during the winter after La Nina,both the Asian trough and the winter monsoon over East Asia are weaker.Compared with LaNina,the effect of El Nino is stronger,but it is not always opposite to the one of La Nina. 相似文献
2.
FEATURES AND COMPARISONS OF THE QUASI-BIENNIAL VARIATIONS IN THE ASIA-PACIFIC MONSOON SUBSYSTEMS 总被引：1，自引：0，他引：1
The National Centers for Environmental Prediction (NCEP) reanalysis data, Climate
Diagnostics Center Merged Analysis of Precipitation (CMAP) results, and NOAA Extended Reconstructed
Sea Surface Temperature (SST), have been utilized in this paper to study the quasi-biennial variations in
Asia-Pacific monsoon subsystems and associated SST anomalies (SSTA) and wind anomalies. Four
monsoon indices are computed from NCEP/ National Center for Atmospheric Research (NCAR) reanalysis
to represent the South Asian monsoon (SAM), South China Sea summer monsoon (SCSSM), Western
North Pacific monsoon (WNPM) and East Asian monsoon (EAM), respectively. The quasi-biennial periods
are very significant in Asia-Pacific monsoons (as discovered by power spectrum analysis), and for SAM
and EAM---with moderate effects by El Ni?o-Southern Oscillation (ENSO)---the quasi-biennial periods are
the most important factor. For SCSSM and WNPM (once again due to the effects of ENSO), the
quasi-biennial periods are of secondary durations. There are obvious interdecadal variations in the
quasi-biennial modes of the Asia-Pacific monsoon, so in the negative phase the biennial modes will not be
significant or outstanding. The wind anomalies and SSTA associated with the biennial modes are very
different in the SAM, WNPM and EAM regions. Since the WNPM and SCSSM are very similar in the
biennial modes, they can be combined into one subsystem, called SCS/WNPM. 相似文献
3.
利用1979—2017年美国国家海洋和大气管理局(NOAA)重建海温逐月资料(ERSST V5)、气候预报中心(CPC)的Ni?o3.4指数、NCEP/NCAR再分析风场资料以及CMAP降水资料,将1979—2017年Ni?o3.4指数超过2 ℃的El Ni?o事件,定义为超强El Ni?o事件。根据超强El Ni?o事件的定义,从近40年(1979—2017年)选取出三个超强El Ni?o事件(1982—1983年、1997—1998年和2015—2016年)。首先运用海温距平资料,分析超强El Ni?o事件的多样性特征,然后根据这三个超强El Ni?o事件发生年与次年的夏季降水距平,讨论东亚夏季风降水对超强El Ni?o事件多样性的响应差异。研究表明,即使是同为超强的El Ni?o事件,由于其不同的分布特征,东亚夏季风降水的响应场表现出明显的不同。在此基础上,从环流异常、850 hPa风场异常以及副高的变化等方面讨论了这两者之间的联系。 相似文献
4.
亚澳季风异常与ENSO准四年变化的联系分析 总被引：2，自引：0，他引：2
分析了赤道地区纬向风的年际变化特征，以及亚澳季风与ENSO在各个位相的联系。结果表明：赤道纬向风变化与中东太平洋海温变化在准四年周期上是强烈耦合的；在El Eino期间东亚冬季风弱，夏季风强，而南亚夏季风弱，反之，在La Nina期间东亚冬季风强，夏季风弱，而南亚夏季风强；东亚地区的异常北风有利于西太平洋西风异常爆发，使得东太平洋海温升高，但只有随后在中东太平洋出现持续性西风异常，El Nino才能发展，其中来自太平洋中部的异常北风（并不是来自东亚大陆地区）和南太平洋中部的异常南风的辐合对中东太平洋出现持续性西风异常起重要的作用，尤其是澳大利亚东北部的季风异常的影响更为显。 相似文献
5.
通过对海温资料和500hPa位势高度、垂直速度、850 hPa的水平风分量资料的分析,探讨ENSO的各不同阶段西太平洋副高和东亚季风的变化特征.结果表明:赤道东太平洋海温与西太平洋副高有密切的关系.Nino 1+2区海温有明显的10年际变化,与西太平洋副高的1O年际变化非常吻合;前期Nino 1+2区为冷、暖水期时西太平洋副高的强度和位置有明显差异,前期为暖水期时夏季西太平洋副高较强,范围向西和向南伸展,冷水期反之,西太平洋副高较弱,位置偏东偏北.西太平洋副高的变化进一步影响东亚季风和我国的降水.这种影响在Nino 1+2区海温变化后4～6个月最明显.因此,前期Nino 1+2区海温的变化可以为东亚季风和我国降水的长期预报提供依据. 相似文献
6.
The time series of sea surface temperature (SST), sea level pressure (SLP), zonal wind (U) and total cloudiness (CA), for the period of 1950-1979, over a 8o×8o grid-point latitudinal belt between 32oS and 32oN are made from COADS (Comprehensive Ocean-Atmosphere Data Set). The time harmonic analysis and power spectra analysis show that there exist quasi-biennial oscillation (QBO), three and half years oscillation (SO), five and half years oscillation (FYO) and eleven years oscillation (EYO) in these time series. The main propagation characteristics of these interannual low-frequency oscillations are as follows:(1) The variance analysis of SST shows that there is an active region of QBO and SO (with maximum variance), coming from the southwestern part of the subtropical Pacific, stretching eastward up to the west coast of South America, and then northward to the eastern equatorial Pacific. The QBO and SO disturbances of SST follow the same route and cause the anomaly of SST (El Nino and period of cold water) in the eastern equatorial Pacific.(2) Either the QBO or SO of SST can cause El Nino events, although it is easier when they are situated in the same phase of warm water at the eastern equatorial Pacific. The FYO of SST seems to be a standing oscillation. It plays an important role on the formation of strong El Nino events or strong cold water events.(3) The QBO and SO of U propagate eastward along the equator. The origin of QBO and SO may at least be traced as far as the western Indian Ocean. While they propagate along the equator, it strengthens two times at 90oE and the western Pacific, respectively. Like SST, the FYO of U is somehow a standing oscillation.(4) The Oscillations of U have a good coupling relationship with those of SST, while they propagate. When the QBO and SO of SST move to the east side of the eastern equatorial Pacific, it is the time for the QBO and SO of U to enter into the east part of the western Pacific.It is clear that, when we do research work on the formation of El Nino events, our consideration would not be confined to the tropics, it should cover the subtropical region in the southern Pacific. The features of the circulation and other oceanic states in this area are very important to the El Nino events. 相似文献
7.
ENSO与亚洲中低纬若干海气因子的遥相关及与华南降水的关系 总被引：1，自引：0，他引：1
本文在统计近一百年左右华南八站降水与ENSO关系基础上,分别探讨了春末夏初亚洲中纬冷空气活动,南海高压及副高脊、盂加拉湾北部低系统和中南半岛季风与ENSO的遥相关,以及它们对华南3—6月降水的影响;台风活动,南海SST与ENSO遥相关及其对华南7—11月降水的影响。指出,El Nino年春夏东亚中纬冷空气活动偏弱,南海高度场偏低,孟加拉湾北部低系统和中南半岛西南季风较活跃。使El Nino年3—6月华南内陆降水偏少而沿海偏多。在ElNino年,南海SSTA有一个由负转正的过程,它使华南沿海在秋台偏少情况下,秋冬有时还有较大的降水甚至带来洪涝。 相似文献
8.
本文分析了1971—80年发生在南美洲西海岸的EI Nino现象及其对东亚夏季风环流的影响。结果表明,1972和1976年为强的EI Nino年,而1971和1974年为显著的反EI Nino年。还指出,1—6月份南美西海岸的海温与7月份我国东部大部分地区夏季风呈负相关.在EI Nino年,主要环流的特征为:(1)西太平洋副热带高压脊线偏北,强度偏弱.(2)澳大利亚高压位置偏南。(3)赤道缓冲脊强大.ITCZ东伸到太平洋中部。南半球的信风在105°E附近越过赤道之后,于10°N折向东去,流入西太平洋.(4)印度次大陆季风中断.孟湾西南季风直接影响我国东部地区的分量极其有限,在反EI Nino年,上述各系统特征完全相反.我们认为,EI Nino现象的发生,引起夏季风环流系统的变动,最终影响到我国夏季风的强度,这是二者之间遥相关的一种可能过程. 相似文献
9.
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
10.
l.Intr0ductionThoughseasonalvariationoftheatmosphericgeneralcirculationismainlycausedbythatofthesolarradiation,itsdistributionsareinhomogeneousovertheglobe,forinstance,itismoresignificantinmonsoonregionthaninanyotherregions.Inatraditionalsense,mon-soonsummarisesalldrasticseasonalvariationsinthetropicsandsubtropics(e.g.,IndiaandEastAsia).Besidestheclassicmonsoonregions,thereexistsomeotherregionsovertheglobe,wheretheseasonalvariationisclearorevendrastic.Inordertodescribequantitativelysea-sonal… 相似文献
11.
INTERANNUAL LOW-FREQUENCY OSCILLATIONS OF MERIDIONAL WINDS OVER THE EQUATORIAL INDIAN-PACIFIC OCEANS 
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下载免费PDF全文 Based on analysis of the meridional winds over oceanic areas and SST for 1950-1979 extracted from the data sets of COADS, the long-term variability of the meridional winds over the equatorial Indian-Pacific oceans and its relationship to the onset and development of El Nino events have been studied. The major results are as follows:(1) There is a great similarity between ITCZ over the Pacific and SST in the seasonal trend, with ITCZ and high SST found in the Southern Hemisphere in winter and in the Northern Hemisphere in summer.During El Nino years, unusual meridional winds were often observed, with significant convergence of meridional winds occurring over near-equatorial regions.(2) For the near-equatorial meridional winds, there are three types of interannual LFO:QBO, SO, FYO. QBO plays an important role in the unusual behavior of meridional winds for El Nino years, while SO is very important for both El Nino and cold water years. These two oscillations may fit well to the observed variation in the meridional wind. FYO may enhance the variation of meridional winds.(3) Interannual LFO of meridional winds originates in the Indian Ocean-Maritime Continent and coastal area of East Pacific. Unusual activities of winter monsoon in both hemispheres and trade winds off the coastal area of East Pacific are believed to be their major cause.(4) Monsoon-trade interaction shows up in the significant amplification of the disturbances of meridional winds while they propagate eastward from monsoon area to trade wind area. 相似文献
12.
Sun-Seon Lee Ye-Won Seo Kyung-Ja Ha Jong-Ghap Jhun 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(2):171-182
The western North Pacific subtropical high (WNPSH) is a crucial component of the East Asian summer monsoon (EASM) system and significantly influences the precipitation in East Asia. In this study, distinguished role of WNPSH on the EASM and Indian Ocean monsoon (IOM) are investigated. Based on the boreal summer mean field of 850-hPa geopotential height and its interannual variability, the WNPSH index (WNPSHI) is defined by the areaaveraged geopotential height over the region [110°–150°E, 15°–30°N]. The WNPSHI is significantly related to the precipitation over the East Asian monsoon (EAM) region [105°–150°E, 30°–40°N] and IOM region [70°–105°E, 5°–15°N]. Rainfalls over these two regions have good correlation with WNPSH developments and the geopotential height fields at 850 hPa related to the EAM precipitation and IOM precipitation have remarkably different teleconnection patterns in boreal summer. These features exhibit that EAM and IOM precipitations have different type of development processes associated with different type of WNPSH each other. Focusing on the relationships among the EAM precipitation, IOM precipitation, and the WNPSH variabilities, we assume that WNPSH and EAM precipitation are usually fluctuated simultaneously through the sea surface temperature (SST)-subtropical ridge-monsoon rainfall feedback, whereas the IOM precipitation varies through the different process. To clarify the relationships among WNPSH, EAM, and IOM, two cases are selected. The first one is the case that all of WNPSH, EAM, and IOM are in phase (WE(+)I(+)), and the second one is the case that WNPSH and EAM are in phase and WNPSH/EAM and IOM is out of phase (WE(+)I(?)). These two cases are connected to the thermal forcing associated with SST anomalies over the eastern Pacific and Indian Ocean. This different thermal forcing induces the change in circulation fields, and then anomalous circulation fields influence the moisture convergence over Asian monsoon regions interactively. Therefore, the monsoon rainfall may be changed according to the thermal conditions over the tropics. 相似文献
13.
Kuang Xueyuan Liu Jian Zhang Yaocun Huang Danqing Huang Ying 《Asia-Pacific Journal of Atmospheric Sciences》2011,47(5):485-495
Based on the simulation results derived from ECHO-G global coupled climate model, several East Asian winter monsoon (EAWM) indices are compared in order to choose the most suitable one for signaling the intensity of winter monsoon in the last millennium. The index I_shi, which is defined with normalized sea level pressure difference between sea and land in mid and low latitudes, is selected to describe the winter monsoon intensity variation owing to its better capability for reflecting the variation of winter monsoon subsystems, such as the continental high pressure, Aleutian low, East Asian major trough, westerly jet stream, and surface air temperature than the other indices examined. Wavelet analysis on index I_shi shows that the EAWM intensity is characterized by multi-timescale variation with inter-annual, decadal, inter-decadal and inter-centennial oscillations on the background of a slight descending trend. Correlation analysis between the EAWM index and sea surface temperature (SST) at various timescales reveals that the SST in mid-latitudes might provide the background of the EAWM strength changes above decadal timescales, and a negative-feedback process lasting for about two years is found between the EAWM intensity and the SST in the eastern equatorial Pacific. According to the correlation, the El Nino occurrence in the second-half of the year leads to weaker EAWM than normal in the following winter and the weakened EAWM corresponds to lower SST in eastern equatorial Pacific after about half a year, which will then strengthen the EAWM intensity in the next winter. It is a stable feedback process and its mechanism is discussed. 相似文献
14.
The interannual variability of East Asian Winter Monsoon and its relation to the summer monsoon 总被引：76，自引：1，他引：75
1.IntroductionOvertheEastAsiaregion,themostprominentsurfacefeatureofthewintermonsoonisstrongnortheasterliesalongtheeastflankoftheSiberianhighandthecoastofEastAsia.At500hPathereisabroadtroughcenteredaboutatthelongitudesofJapan.Thedominantfea-tureat2O0hPaistheEastAsianjetwithitsmaximumlocatedatjustsoutheastofJapan.Thisktisassociatedwithintensebaroclinicity,largeverticalwindshearandstrongadvectionofcoldair(StaffmembersofAcademiaSinica,l957,LauandChang,1987;BoyleandChen,1987;Chenetal.,1991… 相似文献
15.
本文基于华北夏季降水数据、NCEP/NCAR再分析环流数据,采用了相关、合成和环流异常回归重构等方法,分析了东亚副热带夏季风指数、华北大气动力上升指数与华北夏季降水的关系。主要结果如下:1)东亚副热带夏季风指数、华北大气动力上升指数与华北夏季降水有很好的对应关系。当两个指数偏强时,华北夏季降水会异常偏多;两个指数偏弱,华北夏季降水异常偏少;如果两个指数强弱不一致时,华北会出现区域性降水偏多情况,但全区整体降水量基本为正常值。2)华北夏季降水异常是东亚副热带夏季风和华北大气动力上升运动协同作用的结果。在东亚副热带夏季风指数、华北大气动力上升指数偏强年,夏季500 hPa层贝加尔湖槽会加深、西北太平洋副热带高压会偏北,华北处于“东高西低”的环流型控制下,西部低槽东移受阻,在华北维持较长时间的大气上升运动;850 hPa层印度夏季风、东亚副热带夏季风会偏强,这时热带印度洋西风水汽输送以及东亚副热带地区偏南风水汽输送或东南风水汽输送会加强,华北水汽来源充足。这种高、低空环流配置非常有利于造成华北夏季降水异常偏多。反之,华北夏季降水会异常偏少。3)前期4—5月,东亚副热带夏季风指数、华北大气动力上升指数偏强,可以作为华北夏季降水异常偏多的一个气候监测预测指标。 相似文献
16.
东亚季风指数的定义及其与中国气候的关系 总被引：44，自引：6，他引：38
利用NCEP/NCAR 850 hPa月平均风场再分析资料,在客观地选定定义地区范围的基础上;定义了一组新的东亚季风指数:西南季风面积和强度指数,东南季风面积和强度指数,偏北季风面积和强度指数.研究了各季风指数的相互关系、季节变化和年际变异.这6个东亚季风指数突出反映了东亚西南季风、东南季风及偏北季风3支季风气流强度和范围变化的特征.分析表明,它们相互之间既有一定联系,又有独立性.各季风指数存在明显的季节变化和年际变化.另外,分析了各季风指数与中国夏季降水和冬季气温的联系,以考察其解释我国气候异常分布的能力.结果表明,这些指数与我国夏季降水和冬季气温有很好的关系,并各自对应有一定的降水和气温分布.特别是西南季风与东南季风影响我国夏季降水的地区有很大差异.因此,我们指出,研究东亚夏季风时,区别西南季风与东南季风是很有必要的,用单一指数不足以表征它们不同的变化. 相似文献
17.
In this paper, the relation between Asian summer monsoon circulation and sea surface temperature anomalies over equatorial central-eastern Pacific is investigated by using a global spectral model. This model has nine layers in the vertical and the model variables are represented in the horizontal as truncated expansions of the surface spherical harmonics with rhomboidal truncation at wave number 15. The model involves comparatively complete physical pro-cesses and parameterizations with mountains.Using the above model, two experimental schemes are designed, namely control case and anomalous sea surface temperature case. The above two schemes are respectively integrated for forty days and the simulated results are ob-tained from the last 30-day averaged simulations.The simulations show that positive SST anomalies over equatorial central-eastern Pacific weakens Indian mon-soon circulation, decreases precipitation in Indian sub-continent whereas it intensifies East Asian monsoon circula-tion and increases precipitation in East Asian area. All these results reflect the characteristics of Asian summer mon-soon during the El Nino period. In this paper, SST anomalies over equatorial central-eastern Pacific have a direct in-fluence on the intensity and position of subtropical high via the wave train over Northern Hemisphere, which is simi-lar to that suggested by Nitta (1987) and the wave train over Southern Hemisphere has an influence on the intensity of Mascarene high and Australia high resulting in affecting cross equatorial flow. As a result, atmospheric interior heat sources and sinks are redistributed because of the change of cross equatorial flow. And the response of atmos-phere to the new heat source and sink has a significant influence on Asian summer monsoon. 相似文献
18.
ＴｈｅＩｎｆｌｕｅｎｃｅｏｆＴｉｂｅｔａｎＰｌａｔｅａｕｏｎｔｈｅＩｎｔｅｒａｎｎｕａｌＶａｒｉａｂｉｌｉｔｙｏｆＡｓｉａｎＭｏｎｓｏｏｎ①ＷｕＡｉｍｉｎｇ（吴爱明）ａｎｄＮｉＹｕｎｑｉ（倪允琪）ＤｅｐａｒｔｍｅｎｔｏｆＡｔｍｏｓｐｈｅｒｉｃＳｃｉｅ... 相似文献
19.
ENSO 循环各阶段东亚夏季风特征的诊断研究 总被引：2，自引：6，他引：2
利用NCEP／NCAR再分析资料和NCAR海温资料及中国测站地温资料，对ENSO循环不同阶段东亚夏季风强弱变化进行了分析．并从此期间的海陆热力差异和季风低压变化来探讨海温异常对东亚夏季风的影响，结果表明：东亚夏季风指数有明显的年际变化和年代际变化，且与赤道东太平洋SST有较好的负相关关系，其中又以与三个月前的海温变化关系最好．在Ninol 2区为冷、暖水之后的三个月中，冷水期对应的东亚夏季风指数大于暖水期对应的东亚夏季风指数，东亚夏季风比暖水期强。赤道东太平洋SST变化期间亚洲大陆的地面温度和地面气压也有明显变化，这是引起ENSO不同阶段东亚夏季风变化的主要原因。 相似文献
20.
孟加拉湾深对流加热对东亚季风环流系统的影响 总被引：8，自引：2，他引：8
利用40年逐日NCEP/NCAR再分析资料、ReynoldsSST资料和R42L9GOALS模式,研究孟加拉湾深对流加热对东亚副热带季风环流系统的影响及其与ENSO的关系。结果表明:孟加拉湾东岸季风于26候开始爆发,其深对流加热的旋转经验正交函数(REOF)分析表明,其激发的东传Rossby波在中高纬度地区具有相当正压结构。数值试验证实孟加拉湾降水增多,其东侧南海到长江以南区域降水明显减少。分析发现季风环流强度指数极小值和Walker环流强度指数极大值的出现对SSTA转折均具超前性,因此,季风环流的变化对预报ElNino减弱或LaNina结束及SSTA变化趋势具有一定的指示意义。 相似文献