共查询到19条相似文献，搜索用时 125 毫秒
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北半球冬季海平面气压场的气候基本态与气候变率特征及其影响的初步研究 总被引：14，自引：1，他引：13
研究了近100多年冬季北半球海平面气压场的气候基本态、气候变率的特征及时间演变规律。指出北半球冬季海平面气压基本态的标准差的高值区在北太平洋的阿留申低压区、冰岛低压区的西北部及西伯利亚高压区。基本态的第一特征向量表现为弱西伯利亚高压、强北大西洋高压的强纬向环流的特征;第二特征向量表现为弱阿留申低压及强北太平洋高压。研究还指出,阿留申低压区及冰岛低压区在基本态改变的同时,标准差也有长期变化,而且主要表现为近百年中变率线性增大。此外,北半球冬季气温及我国冬季气温的长期变化都与北半球冬季海平面的基本态变化有关。 相似文献
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王绍武 《气候变化研究进展》2010,6(3):233-234
<正>大气涛动的研究至今已有百年以上的历史。19世纪末,当人们开始绘制月平均海平面气压图时,就发现了"大气活动中心",即相对稳定的高压区或低压区。有些低压及高压终年存在,被称为永久性活动中心,如北大西洋上的冰岛低压和亚述尔高压、北太平洋上的阿留申 相似文献
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不同年代际背景下AO与冬季中国东北气温的关系 总被引：3，自引：1，他引：2
采用1951—2006年北极涛动指数序列、NCEP/NCAR再分析资料和我国160站气温资料,利用滑动相关分析研究了不同年代际背景下北极涛动与冬季中国东北气温年际异常关系的变化情况。结果表明,两者的关系在20世纪60年代中后期显著增强,在80年代中后期减弱。不同年代际背景下,与AO相关联的中高纬度大气环流异常发生的明显改变是AO与东北冬季气温关系发生年代际变化的原因。强相关年代,西伯利亚高压与阿留申低压均明显减弱,东亚冬季风偏弱,对流层中下层异常东南风控制东北地区,对流层中层东亚大槽明显减弱,环流的经向性减弱,使该地区冬季气温偏高;相关较弱的年代则以上表现不明显。 相似文献
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华南初夏干旱及多雨年份的季风环流特征 总被引：2，自引：0，他引：2
本文根据1961—1980年我国华南5月降水量资料,划分5月的旱或涝。并挑选1963、1966(干旱)1973、1975(涝)四年作为典型年,从天气气候角度分析了初夏季风环流结构与华南5月旱涝关系。华南地区旱5月和涝5月在夏季风来临早迟、持续期长短、强度强弱等方面都有明显差异。华南5月出现旱或涝,不仅在同期全球环流,而且在前期环流,特别是北半球中高纬度几个活动中心也有明显的差异。1月以阿留申低压及冰岛低压,4月以太平洋高压及大西洋高压差别比较明显。华南5月降水量的多少与前期3月低纬气压指标值有较好关系,涝 相似文献
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20世纪两次全球增暖事件的比较 总被引：12，自引：1，他引：11
20世纪20年代和70年代全球出现了两次突变增暖,本文分析比较了这两次全球增暖的起源地,空间分布特点,影响范围,以及北半球增温和降温最大地区的气温变化与其相对应的大气环流变化的联系等.发现,第一次全球增暖始于北半球新地岛西北、冰岛及以北的极地地区,主要增暖区在北大西洋、格陵兰岛、冰岛和北半球中、高纬大陆地区,主要增暖季节是夏季.第二次全球增暖最早可能始于南半球南印度洋海盆及南极大陆地区,增暖中心有明显向北半球方向移动的倾向并广泛影响到全球热带、副热带海洋,没有明显的区域和季节增暖差异;北半球第二次增暖比南半球约晚10年,主要增温区在东亚大陆和北美西部,主要增暖季节在冬季.分析还发现,20世纪北半球增暖最强的东亚大陆、北美西北部和降温显著的冰岛、格陵兰岛、北大西洋以及中北太平洋等地的气温变化与其相应的大气环流系统的异常变化关系密切. 相似文献
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利用1980~2014年CRU TS3.24月平均气温数据和NCEP/NCAR再分析资料,分析了中国东北暖季（5~9月）气温的时空变化特征及其相应的大气环流状况。结果表明:中国东北暖季气温主要表现为全区一致型和南北反位相型两个模态,二者总解释方差高达86%。全区一致型具有明显的年代际变化特征,并在1990年代中期发生了显著的年代际突变,而南北反位相型具有明显的年际和年代际变化特征。全区一致型增暖对应着中国东北地区上空500 hPa位势高度的正异常和850 hPa的反气旋环流异常。当500 hPa位势高度南北反相时,对应于中国东北暖季气温的南北反位相型。进一步分析表明中国东北暖季气温的全区一致型及其1990年代中期的年代际突变与日本海及黑潮延伸区的海温异常及太平洋年代际振荡和大西洋多年代际振荡指数紧密相关。菲律宾以东的西太平洋、北太平洋中部、我国东南沿海、靠近北美东北部的北大西洋等海域的海温异常对中国东北暖季气温全区一致型的出现具有一定的预测作用。而南北反位相变化型与黑潮延伸区的海温异常关系显著,与大尺度指数的相关普遍不明显。在1990年代中期突变前,南北反位相型受到ENSO事件的影响,之后影响不显著。 相似文献
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北半球冬季环流异常与ENSO的非线性关系 总被引：1，自引：0，他引：1
运用非线性典型相关分析（nonlinear canonical correlation analysis,简称NLCCA）方法,对热带太平洋海表温度异常（SSTA）场与北半球冬季海平面气压异常场（SLPA）进行非线性分析,以反映ENSO与北半球冬季环流异常之间的非线性关系。NLCCA的结果表明：从极冷到极暖期,北半球冬季SLPA场对ENSO的投影在各主成分所分别构成的平面或空间中分别形成一条直线和一条抛物线,说明北半球冬季环流异常与ENSO的相关包含线性和具有二次特征的非线性两部分。无论ENSO的冷、暖事件都能导致冰岛低压减弱,且西伯利亚高压、北美高压和北太平洋高压随SSTA的变化不对称,进一步证明了ENSO对北半球冬季环流异常的非线性影响,其中冰岛低压对于ENSO响应的非线性特征最强,而阿留中低压与ENSO则主要是线性相关。 相似文献
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冬春季格陵兰海冰变化与初夏中国气温/降水关系的初步分析 总被引：3，自引：5，他引：3
采用英国Hadley中心GISST海冰面积资料，NCEP／NCAR再分析资料以及中国地面降水和气温资料，运用EOF分解，小波分析和合成分析等方法，初步探讨了格陵兰岛两侧附近冬春季海冰面积变化特征及其与初夏6月中国气温和降水的关系，结果表明，格陵兰岛东西两侧海冰面积呈显著反相变化，并且具有明显的年际和年代际周期性振荡，冬春季格陵兰－寻威海海冰与初夏6月中国长江以北气温（降水）正相关（反相关），与长江以南气温（降水）反相关（正相关），而对于戴维斯海峡－拉布拉多海海冰则具有相反的相关型，大尺度500hPa环流合成分析初步表明，冬春季格陵兰附近海冰面积变化伴随着北极极涡环流和北半球阻塞高压的持续异常，海冰变化可能是影响初夏中国气温和降水的因子之一。 相似文献
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春季格陵兰海冰变化及与北大西洋涛动和北极涛动的联系 总被引：1，自引：0，他引：1
采用长序列(1903—1994年)GISST海冰面积和海表温度(SST)资料、NCEP／NCAR再分析资料等，分析了春季格陵兰海冰面积年代际变化特征及其同北大西洋海气变化的关系。结果表明：春季格陵兰海冰面积变化的主要特征可由海冰变化的EOF第一主分量表示。春季海冰变化与前冬NAO／AO以及冬春1—4月份北大西洋墨西哥湾流区SST具有明显的反相变化趋势，且均具有准60a的周期变化特征。海洋向大气的热量输送(感热、潜热)受到海冰变化的显著影响(冰多输送少)。海冰作为大气的冷源，也明显影响地表净辐射的变化。进而，春季海冰变化可影响后期的大气环流变化：海冰面积偏大(偏小)，冰岛低压和阿留申低压偏弱(偏强)，夏季北非和亚洲大陆的SLP明显偏低(偏高)，两大陆夏季热低压加强(减弱)。 相似文献
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近20年全球冬、夏季海平面气压场和500 hPa高度场年代际变化特征分析 总被引：19，自引：14，他引：19
利用1958－1997年全球海平面气压场和500hPa高度场的月平均资料分析了70年代中后期年代际突变前后16a平均的冬、夏海平面气压场和500hPa高度场的变化特征。结果表明，发生在70年代中后期的年代际气候突变是全球性的；突变后与突变前相比，冬季海平面气压场上的阿留申低压增强并发生了东移，与之对应的冬季500hPa高度场上的东亚大槽减弱，同时也发生了明显的系统性东移；冬季，蒙古高压北部减弱，南部稍有增强；夏季，印度低压和东亚的季风低压均减弱；而副热带高压系统普遍增强。 相似文献
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Global climate change and variability and its influence on Alpine climate — concepts and observations 总被引：1，自引：0，他引：1
H. Wanner R. Rickli E. Salvisberg C. Schmutz M. Schüepp 《Theoretical and Applied Climatology》1997,58(3-4):221-243
Summary The paper discusses annual to decadal climate variability and change in the European Alps by utilizing the procedure of synoptic downscaling, i.e. it investigates the influence of global to continental scale synoptic structures and processes on the regional climate of the Alps. The European Alps lie to the southeast and under the right exit zone of the southwest-northeast oriented axis of the polar front jet over the North Atlantic ocean, in a transition zone between the Azores high and Icelandic low, between oceanic and continental and between Mediterranean and North Atlantic climates. Together with complex topographically induced phenomena like lee cyclogenesis, orographic precipitation, strong downslope winds and thermotopographical circulation systems, this transitional position makes climate studies in the Alps even more interesting. Only a minor correlation can be observed between global climate variability and Alpine climate. In contrast, the Alpine climate is strongly related to processes over the North Atlantic ocean and its sea ice system (e.g. it has a high correlation with the North Atlantic Oscillation and the dynamics and position of the Icelandic low), an area with a rather low climate prediction potential.Since the early 1970's (or just after the Great Salinity Anomaly in the North Atlantic Ocean) the intensification of the wintertime westerly jet over the North Atlantic area led to a noticeable northwest-southeast mass transport in the exit area of the jet over Central Europe, leading to pressure and temperature rises and an increase in the amount of precipitation. There is a question over whether this phenomenon is a consequence of natural climate variability or the beginning of an anthropogenic climate change.With 16 Figures 相似文献
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The study of low-frequency oscillations is an important part of climate variability research. In view of insufficient efforts spent on multidecadal and ENSO-scale changes of the climate, the present paper undertakes study of > 30 year slowly-varying means, called climate base state (CBS), of northern winter AAC's in the past 100 years and more, with the CBS variability and its temporal evolution investigated, indicating that Aleutian low and Icelandic low (North Pacific high and North American high) experience maximum (minimum) variation in the CBS. The CBS exhibits two modes for its variation. The positive (negative) phase of mode Ⅰ presents a weak (strong) NAO (North Atlantic Oscillation), a weaker (stronger) NPO (North Pacific Oscillation), a robust (feeble) Siberian high and a quite weak (vigorous) Aleutian low whilst the positive (negative) phase of mode Ⅱ reveals a feeble (strong) Aleutian low and a weak (robust) Siberian high. Also, the research shows that the recent CBS of northern circulations is in a remarkably negative phase of mode Ⅰ and a noticeably positive phase of mode Ⅱ, viz., in the background of slowly-varying circulations of an exceptionally weak Siberian high, an extremely vigorous Aleutian low and an intense NAO. The background field is likely to persist for a matter of 30 years such that northern winter temperature is expected to be in such a warm situation for a long period to follow. 相似文献
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Øyvind Byrkjedal Nils Gunnar Kvamstø Marius Meland Eystein Jansen 《Climate Dynamics》2006,26(5):473-487
Published reconstructions of last glacial maximum (LGM) sea surface temperatures and sea ice extent differ significantly.
We here test the sensitivity of simulated North Atlantic climates to two different reconstructions by using these reconstructions
as boundary conditions for model experiments. An atmospheric general circulation model has been used to perform two simulations
of the (LGM) and a modern-day control simulation. Standard (CLIMAP) reconstructions of sea ice and sea surface temperatures
have been used for the first simulation, and a set of new reconstructions in the Nordic Seas/Northern Atlantic have been used
for the second experiment. The new reconstruction is based on 158 core samples, and represents ice-free conditions during
summer in the Nordic Seas, with accordingly warmer sea surface temperatures and less extensive sea ice during winter as well.
The simulated glacial climate is globally 5.7 K colder than modern day, with the largest changes at mid and high latitudes.
Due to more intense Hadley circulation, the precipitation at lower latitudes has increased in the simulations of the LGM.
Relative to the simulation with the standard CLIMAP reconstructions, reduction of the sea ice in the North Atlantic gives
positive local responses in temperature, precipitation and reduction of the sea level pressure. Only very weak signatures
of the wintertime Icelandic Low occur when the standard CLIMAP sea surface temperature reconstruction is used as the lower
boundary condition in LGM. With reduced sea ice conditions in the Nordic Seas, the Icelandic Low becomes more intense and
closer to its present structure. This indicates that thermal forcing is an important factor in determining the strength and
position of the Icelandic Low. The Arctic Oscillation is the most dominant large scale variability feature on the Northern
Hemisphere in modern day winter climate. In the simulation of the LGM with extensive sea ice this pattern is significantly
changed and represents no systematic large scale variability over the North Atlantic. Reduction of the North Atlantic sea
ice extent leads to stronger variability in monthly mean sea level pressure in winter. The synoptic variability appears at
a lower level in the simulation when standard reconstructions of the sea surface in the LGM are used. A closer inspection
of storm tracks in this model experiment shows that that the synoptic lows follow a narrow band along the ice edge during
winter. The trajectories of synoptic lows are not constrained to the sea ice edge to the same degree when the sea ice extent
is reduced. Seasonally open waters in the Nordic Seas in the new reconstruction apparently act as a moisture source, consistent
with the current understanding of the rapid growth of the Fennoscandian and Barents Ice Sheets, during the LGM. The signal
from the intensified thermal forcing in the North Atlantic in Boreal winter is carried zonally by upper tropospheric waves,
and thus generates non-local responses to the changed sea ice cover. 相似文献
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Several studies demonstrate that North Atlantic Oscillation influences variability of climate over Middle East. We use the centers of action approach for the study of winter rainfall variability over Middle East, taking into account variations in the components of the North Atlantic Oscillation, the Azores High and the Icelandic Low pressure systems. The results show there is a negative relation between the interannual variations of winter rainfall over Middle East and Azores High pressure. The east–west shifts of Indian Ocean high pressure has also impact on precipitation over Middle East, there being more precipitation when the Indian Ocean High shifts eastward versus when it is westward. We present a regression model for Middle East precipitation in which the Azores High pressure and the Indian Ocean High longitude are independent variables and it explains 40 % of the variance of precipitation during 1952–2002. Furthermore, the ongoing decrease in winter precipitation over the Middle East is attributed to the increasing pressure of the Azores High over the same period. 相似文献
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赵勇 《沙漠与绿洲气象(新疆气象)》2013,7(6):1-7
基于1961-2008年天山区域24站云量的逐日资料,使用相关和M原K检验等统计方法,分析中国天山区域云量的时空变化特征及其与降水的关系。结果表明：（1）春季、秋季和冬季,伊犁河谷以北总云量最多,夏季则在中天山和东天山的部分区域最多,低云量在夏季占总云量的比重最大;（2）区域平均总云量在春季和秋季呈减少趋势;低云量在各季节均呈增加趋势,尤其在冬季和夏季;（3）总云量的年代际变化不明显,而低云量自20世纪90年代至今,都处在高值期。（4）低云量在春季、夏季和秋季,均在20世纪90年代,而冬季在2000年左右发生了由少到多的气候突变;总云量未发生明显的气候突变。（5）总云量和低云量均和同期降水有较好的相关性。春季低云量和夏季降水,相关系数可达0.52。 相似文献
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The synoptic circulation over Saudi Arabia is complicated and frequently governed by the effect of large-scale pressure systems. In this work, we used NCEP–NCAR global data to illustrate the relationship between climatic variables and the main pressure systems that affect the weather and climate of Saudi Arabia, and also to investigate the influence of these pressure systems on surface air temperature(SAT) and rainfall over the region in the winter season. It was found that there are two primary patterns of pressure that influence the weather and climate of Saudi Arabia. The first occurs in cases of a strengthening Subtropical High(Sub H), a weakening Siberian High(Sib H), a deepening of the Icelandic Low(Ice L), or a weakening of the Sudanese Low(Sud L). During this pattern, the Sub H combines with the Sib H and an obvious increase of sea level pressure(SLP) occurs over southern European, the Mediterranean, North Africa, and the Middle East. This belt of high pressure prevents interaction between midlatitude and extratropical systems, which leads to a decrease in the SAT,relative humidity(RH) and rainfall over Saudi Arabia. The second pattern occurs in association with a weakening of the Sub H, a strengthening of the Sib H, a weakening of the Ice L, or a deepening of the Sud L. The pattern arising in this case leads to an interaction between two different air masses: the first(cold moist) air mass is associated with the Mediterranean depression travelling from west to east, while the second(warm moist) air mass is associated with the northward oscillation of the Sud L and its inverted V-shape trough. The interaction between these two air masses increases the SAT, RH and the probability of rainfall over Saudi Arabia, especially over the northwest and northeast regions. 相似文献