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1.
100hPa极涡、南亚高压的变化及大气环流分布特征 总被引:8,自引:0,他引:8
利用NCEP/NCAR高度场资料进行计算,对冬、夏极涡与南亚高压面积进行Morlet小波变换,并对100 hPa高度场进行EOF分解和长期趋势分析.结果表明:极涡、南亚高压具有相似的演变特征,这种相似特征在前期冬季极涡与南亚高压之间表现更为明显,体现了准5年尺度和准20年尺度的周期变化,在变化的位相上则相反.EOF分析表明,前期冬季高纬度地区与中低纬度地区的环流变化呈相反趋势,且第一模态的时间系数与前期冬季极涡的趋势一致,第一模态在一定程度上反映了前期冬季大气环流分布.夏季第一模态全场为负值,体现了夏季100 hPa整体异常性;第二模态反映了副热带中低纬度大气环流与高纬度大气环流变化相反.从其长期变化趋势来看,冬季高纬度地区的高度场呈负趋势变化,副热带地区呈正趋势变化,夏季除我国华北部分地区为负趋势变化外,均为正趋势变化.极涡、南亚高压的这种年代际变化与100 hPa高度场的长期线性趋势变化有关. 相似文献
2.
根据热带印度洋和热带太平洋(22.5 S~22.5 N,42.5 E~77.5 W )1951~1995年逐月5 ×5 的海面温度距平资料,首先进行了海面温度距平的平均功率谱分析,获取赤道印度洋和赤道太平洋海面平均温度距平存在准12年和准4年的周期变化;然后,利用多维时间序列的交叉谱分析,进一步分别分析了赤道印度洋和赤道太平洋各格点上海面温度距平在准12年和准4年演变周期各格点之间的演变位相及演变落后时间,获得一些有意义的结论。 相似文献
3.
1991年江淮梅雨与副热带高压的低频振荡 总被引:47,自引:4,他引:43
利用NCEP/NCAR再分析资料和观测的台站降水资料研究了1991年梅雨期间江淮洪涝区降水的季节内振荡及其环流特征,着重考察了不同层次副热带高压的低频变化与降水的关系。小波分析表明1991年江淮梅雨期间降水低频振荡的主周期是15~35 d。在低空,15~35 d振荡以异常反气旋(气旋)的形式在中国东南沿海地区交替出现,调控着西太平洋副热带高压进入(退出)南海。低空的这种低频环流型与高空的偶极型涡旋对相耦合,偶极型涡旋对使得南亚高压东伸(西退),形成有利(不利)江淮流域降水的环流形势。江淮流域降水的低频振荡与500hPa北太平洋副热带高压的低频变化及其传播密切相关。当北太平洋西部的位势高度偏高、中部位势高度偏低时,江淮流域降水偏多;反之偏少。这种低频振荡可能起源于北太平洋中部夏威夷群岛附近,然后沿着副热带高压脊线附近向西传播到中国东南沿海。 相似文献
4.
An intercomparison of summertime (JJA)subtropical geopotential heights from the ERA-40 and NCEP/NCAR reanalysis is specifically conducted over East Eurasia and the western North Pacific. The NCEP/NCAR is obviously lower than the ERA-40 in the mid-to-lower troposphere in most regions of East Eurasia before the mid-1970s, but becomes higher than the ERA-40 after the mid-1970s and thus demonstrates stronger increased trends during the period of 1958-2001. Both reanalyses are lower than the observations in most regions of China. The NCEP/NCAR especially shows tremendously systematic lower values before the mid-1960s and displays abrupt changes before the 1970s. Several indices of the western North Pacific subtropical high (WNPSH), calculated from both reanalyzed summer geopotential heights, also reveal that the variation trend of the NCEP/NCAR is stronger than that of the ERA-40 in the mid-to-lower troposphere from 1958 to 2001. Through singular value decomposition (SVD) analysis, the summer geopotential heights at 500 hPa from the ERA-40 are better than the NCEP/NCAR counterparts at interacting with the precipitation over the East Asian monsoon region. The results indicate that the NCEP/NCAR in the mid-and-lower troposphere may overestimate interdecadal changes and should be used cautiously to study the relationship between the WNPSH and precipitation ove ther East Asia Monsoon region before the mid-1970s. 相似文献
5.
DISTRIBUTION OF LOW FREQUENCY WAVES IN NORTH PACIFIC AND INTRASEASONAL ABNORMALITY OF THE WESTERN PACIFIC SUBTROPICAL HIGH 总被引:4,自引:0,他引:4
By using ECMWF (2.5°×2.5°) grid data, analyzing correlation for the summer (June-August) of 1980 (the West Pacific Subtropical High (WPSH) anomalously more to the south), 1988 (the WPSH anomalously more to the north), 1981 (normal) in the west Pacific area, distribution characteristics of the low frequency waves are discussed. The relationship between distribution of the low frequency waves and intraseasonal abnormality of the west subtropical high is also analyzed. There is some discussions:(1)If the WPSH acts anomalously in summer, there is a distinct zonal wave series in the subtropical zone of the north Pacific.(2) One of the important characteristics of the WPSH abnormality is that there are low frequency geopotential high centres from east Pacific and northeast Asia, being combined in the west Pacific area.For different circulation, the combination areas are different, which define the WSPH anomalously more to the north or south. 相似文献
6.
Intercomparison of the Summertime Subtropical High
from the ERA-40 and NCEP/NCAR Reanalysis over
East Eurasia and the western North Pacific 总被引:2,自引:1,他引:1
An intercomparison of summertime (JJA) subtropical geopotential heights from the ERA-40 and NCEP/NCAR
reanalysis is specifically conducted over East Eurasia and the western North Pacific. The NCEP/NCAR is obviously
lower than the ERA-40 in the mid-to-lower troposphere in most regions of East Eurasia before the mid-1970s, but
becomes higher than the ERA-40 after the mid-1970s and thus demonstrates stronger increased trends during the
period of 1958--2001. Both reanalyses are lower than the observations in most regions of China. The NCEP/NCAR
especially shows tremendously systematic lower values before the mid-1960s and displays abrupt changes before
the 1970s. Several indices of the western North Pacific subtropical high (WNPSH), calculated from both reanalyzed
summer geopotential heights, also reveal that the variation trend of the NCEP/NCAR is stronger than that of the
ERA-40 in the mid-to-lower troposphere from 1958 to 2001. Through singular value decomposition (SVD) analysis,
the summer geopotential heights at 500 hPa from the ERA-40 are better than the NCEP/NCAR counterparts at
interacting with the precipitation over the East Asian monsoon region. The results indicate that the NCEP/NCAR
in the mid-and-lower troposphere may overestimate interdecadal changes and should be used cautiously to study
the relationship between the WNPSH and precipitation ove ther East Asia Monsoon region before the mid-1970s. 相似文献
7.
采用NCEP/NCAR再分析逐日资料和SCSMEX等资料,根据全型垂直涡度倾向方程,研究了1998年6月西太平洋副高位置变动与大气热源的关系。结果表明,副热带地区的非绝热加热对副高位置变化有很重要的作用。与气候平均状况相比,1998年6月副高北侧的非绝热加热垂直变化较常年偏强,而南侧较常年偏弱。这种异常的非均匀加热状况导致我国华南、江南、长江中下游地区呈现异常气旋性涡度制造,而中南半岛大部和南海地区为异常反气旋性涡度制造,使得1998年6月副高位置异常偏南。 相似文献
8.
西太平洋副高的东西进退与东亚夏季风系统的相互影响与关联 总被引:2,自引:1,他引:1
利用1980-2010年NCEP/NCAR再分析资料和美国NOAA向外长波辐射(outgoing longwave radiation,OLR)资料,根据关键区500 hPa位势高度的变化定义了西太平洋副高东西位置指标,利用该指标围绕东亚夏季风系统开展分析,详细对比了夏季6月、7月副高东西向活动异常时,季风区相应的环流及对流活动差异.结果表明:副高东西位置的年际变化反映了亚洲夏季风的强弱变化,副高偏西(东)年,南海夏季风偏弱(强),副热带夏季风偏强(弱);副高的东西进退与东亚夏季风系统成员之间相互影响、相互制约;副高偏西年,南亚高压偏东、偏强,季风槽不发展、强度偏弱,西风带长波槽发展加深,南半球马斯克林高压和澳大利亚高压减弱,越赤道气流减弱,而副高偏东年情况则反之. 相似文献
9.
1993年北半球环流特征及其对我国天气气候的影响 总被引:4,自引:0,他引:4
1993年北半球主要环流特征表现为:500hPa副产持续加强西伸,位置偏南;亚洲中纬度春,夏经向环流发展,东亚太平洋遥相关型稳定;西藏高原500hPa位势高度持续偏高,印缅槽持续偏弱;100hPa位势高度场低纬持续偏高,中,高纬持续偏低,夏季南亚高压位置异常偏高。热带海洋出现明显异常,一次新的厄尔尼诺现象发生。热带海洋和北半球大气环流的异常对我国天气气候产生明显影响。 相似文献
10.
利用重建的1880-1950年500 hPa高度场资料和1951-2004年的NCEP/NCAR再分析资料,分析了年际尺度上东亚地区夏季大气环流变化特征。结果表明:夏季在东亚沿岸存在一个明显的自北向南的正-负-正环流模态,即鄂霍次克海阻塞高压与副热带高压存在一种同向变化、而它们之间区域的高度场为反向变化的遥相关关系;同时分析了这种大气环流模态与1880-2004年中国东部地区夏季降水的关系。在年际尺度上,正-负-正的环流模态与长江中下游地区和东北的降水有很好的正相关,当夏季的环流处在阻塞高压偏强,且副热带高压偏南偏强、日本及其以东地区上空高度场偏低时,中国长江中下游地区和东北降水偏多。 相似文献
11.
利用重建的1880-1950年500 hPa高度场资料和1951-2004年的NCEP/NCAR再分析资料,分析了年际尺度上东亚地区夏季大气环流变化特征。结果表明:夏季在东亚沿岸存在一个明显的自北向南的正-负-正环流模态,即鄂霍次克海阻塞高压与副热带高压存在一种同向变化、而它们之间区域的高度场为反向变化的遥相关关系;同时分析了这种大气环流模态与1880-2004年中国东部地区夏季降水的关系。在年际尺度上,正-负-正的环流模态与长江中下游地区和东北的降水有很好的正相关,当夏季的环流处在阻塞高压偏强,且副热带高压偏南偏强、日本及其以东地区上空高度场偏低时,中国长江中下游地区和东北降水偏多。 相似文献
12.
利用国家气候中心整编的中国160个测站的月降水资料,提取1951—2012年江淮流域26站6、7月份的梅雨量距平场资料进行EOF分析,将梅雨雨型分为北涝南旱型和南涝北旱型。利用NCAR/NCEP再分析资料对两种空间分布的典型年大气环流背景特征进行合成分析,结果表明:北涝南旱年,高纬度鄂霍次克海高压阻塞形势偏强,极涡偏弱,西太平洋副热带高压和南亚高压位置偏北,东亚副热带夏季风偏强,水汽辐合中心偏北;南涝北旱年情形基本相反,高纬度鄂霍次克海高压阻塞形势和极涡偏强,西太平洋副热带高压和200 hPa南亚高压位置偏南,东亚副热带夏季风偏弱,水汽辐合中心偏南。 相似文献
13.
利用NCEP/NCAR提供的位势高度场、温度场资料和NOAA提供的OLR资料,应用EOF分析和相关分析等方法,分析南海区域(107.5°-120°E、12.5°-22.5°N)OLR的异常特征及其与2007年广东省高温天气的关系。结果表明,南海区域对100°-120°E、0°-35°N区域内OLR异常分布的主要时空型贡献最大,即该区域OLR的变率最大。OLR的分布基本可以反映出副热带高压的位置和强度,OLR值偏大、中心偏西,则副热带高压偏强、偏西。上空对流偏弱,下沉增温是造成2007年7月广东省长时间、大范围高温天气的主要原因之一。 相似文献
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1 INTRODUCTION An important constituent in the Asian summer monsoon system, the West Pacific subtropical high (simplified as the 揌igh) is closely related with the activity of summer monsoon via the changes in intraseasonal intensity and progression[1 - 8]. Zhang et al[5]. discuss the relationship between seasonal jumps and anomalous location of the Highs ridge and onset of low-latitude westerlies and tropical convection in summer, with the finding that the northward jump of the High is … 相似文献
16.
THE POSITION VARIATION OF THE WEST PACIFIC SUBTROPICAL HIGH
AND ITS POSSIBLE MECHANISM 总被引:2,自引:0,他引:2
Using NCEP/NCAR daily reanalysis data and SCSMEX data, an investigation is carried out of
the relationship between the position variation of the west Pacific subtropical high (WPSH) and the apparent
heating in June 1998 based on the complete vertical vorticity equation. It is found that the non-adiabatic heating
plays an important role in the position variation of WPSH. In comparison with climatic mean status, the vertical
change of non-adiabatic heating is stronger in the north side of WPSH in June 1998, but weaker in the south side
of WPSH. The anomalous non-uniform heating induces anomalous cyclonic vorticity in South China, areas to the
south of the Yangtze and its mid-lower valleys, but anomalous anticyclonic vorticity in the Indo-China Peninsula
and South China Sea areas lead to the more southward position of WPSH than the mean. 相似文献
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1997年北半球大气环流特征及其影响 总被引:1,自引:0,他引:1
1997年北半球主要环流特征为:500hPa西太平洋副热带高压盛夏由弱转强、西伸明显、脊线位置偏北;亚洲中纬度经、纬向环流交替出现,纬向环流盛行,春、秋季经向环流加强,冬、夏季冷空气异常偏弱;盛夏南海季风增强,印度季风偏弱;赤道辐合带偏弱。北半球100hPa中低纬度位势高度持续偏高,南亚高压东扩明显;热带海洋出现异常,一次新的厄尔尼诺事件发生,强度大、发展快。在ENSO和大气环流的共同影响下我国天 相似文献
20.
This study aims to explore the interdecadal variation of South Asian High (SAH) and its relationship with SST (Sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis data from 1948 to 2012, based on the NCAR CAM 3.0 general circulation model. The results show that: 1) the intensity of SAH represents a remarkable interdecadal variation characteristic, the intensity of SAH experienced from weak to strong at the late 1970s, and after the late 1970s , its strength is enhanced and the area is expanded in the east-west direction. The expansion degree is greater westward than eastward, while it is opposite in summer. 2) Corresponding to the interdecadal variation of SAH intensity, after the late 1970s, the divergent component of wind field has two ascending and three descending areas. Of the two ascending areas, one is located in the East Pacific, the other location varies with the season from the Indian Ocean in winter to the South China Sea and West Pacific in summer. Three descending areas are located in the north-central Africa, the East Asia and the Middle Pacific region respectively. 3) Corresponding to the interdecadal variation of SAH intensity, the rotational component of wind field at the lower level is an anomalous cyclone over the South China Sea and West Pacific in summer, while in winter, it is an anomalous cyclone over the Indian Ocean, and an anomalous anticyclone over the equatorial Middle Pacific. 4) Numerical simulations show that the interdecadal variation of SAH is closely related to the SST of the tropical and subtropical regions. The SST of Indian Ocean plays an important role in winter, while in summer, the SST of the South China Sea and West Pacific plays an important role, and the SST of the East Pacific also plays a certain role. 相似文献