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1.
基于两种潜在蒸散发算法的SPEI对中国干湿变化的分析   总被引：12，自引：0，他引：12  
刘珂  姜大膀 《大气科学》2015,39(1):23-36
利用美国普林斯顿大学高分辨率的全球陆面同化数据集和美国国家环境预测中心的辐射再分析数据,根据Thornthwaite和Penman-Monteith公式分别计算了1948～2008年中国区域潜在蒸散发量;而后,使用降水和两套潜在蒸散发数据分别计算得到标准化降水蒸散发指数SPEI(Standardized Precipitation Evapotranspiration Index),并以此研究了1949～2008年中国区域干湿变化时空特征以及两种SPEI结果之间的差异;最后,给出了两种SPEI在中国的适用区域。结果表明:两种SPEI均显示中国地区整体上存在变干趋势,季节上以春季的变干趋势最为显著;空间上表现为以长江为界的南涝北旱,显著变干的区域有内蒙古中部、华北、东北以及四川东部地区,显著变湿的地区主要位于新疆北部和西部。同时,各种不同等级干旱也呈增加趋势,其中以中等干旱增加最为显著。1990年代中后期以来是中等和极端干旱发生最多的时期,空间上与SPEI显著减小的区域相对应。两种SPEI在 冬、春季差异最大,这主要是由于期间两种潜在蒸散发的计算结果之间存在很大差异。在Penman-Monteith公式中,由于空气动力项对冬、春季北方潜在蒸散发的贡献显著增加,基于该公式的SPEI相对而言能更合理地描述干湿变化特征。  相似文献   

2.
This study investigates the statistical linkage between summer rainfall in China and the preceding spring Eurasian snow water equivalent (SWE), using the datasets of summer rainfall observations from 513 stations, satellite-observed snow water equivalent, and atmospheric circulation variables in the NCEP/NCAR re-analysis during the period from 1979 to 2004. The first two coupled modes are identified by using the singular value decomposition (SVD) method. The leading SVD mode of the spring SWE variability shows a coherent negative anomaly in most of Eurasia with the opposite anomaly in some small areas of the Tibetan Plateau and East Asia. The mode displays strong interannual variability, superposed on an interdecadal variation that occurred in the late 1980s, with persistent negative phases in 1979--1987 and frequent positive phases afterwards. When the leading mode is in its positive phase, it corresponds to less SWE in spring throughout most of Eurasia. Meanwhile, excessive SWE in some small areas of the Tibetan Plateau and East Asia, summer rainfall in South and Southeast China tends to be increased, whereas it would be decreased in the up-reaches of the Yellow River. In recent two decades, the decreased spring SWE in Eurasia may be one of reasons for severe droughts in North and Northeast China and much more significant rainfall events in South and Southeast China. The second SVD mode of the spring SWE variability shows opposite spatial variations in western and eastern Eurasia, while most of the Tibetan Plateau and East Asia are in phase. This mode significantly correlates with the succeeding summer rainfall in North and Northeast China, that is, less spring SWE in western Eurasia and excessive SWE in eastern Eurasia and the Tibetan Plateau tend to be associated with decreased summer rainfall in North and Northeast China.  相似文献   

3.
Characteristics of anomalous precipitation events during the past five centuries in North China (NC) and the middle-lower Yangtze River Valley (MLYRV) were investigated using the data network of dryness/wetness index (DWI) over eastern China. The high occurrence frequency of anomalous precipitation events mainly occurred at periods of high solar forcing, active volcanic eruption, and large anthropogenic forcing (the twentieth century). Coherence and dipole were the two dominant modes in spatial patterns of anomalous precipitation events. Coherent floods dominated the eighteenth and nineteenth centuries, whereas coherent droughts occurred frequently in the seventeenth and twentieth centuries. The dipole patterns of anomalous precipitation events were the most frequent in the twentieth century. NC experienced more floods in the cold periods than warm periods. Both NC and the MLYRV experienced far fewer droughts and more floods in the warm eighteenth century when natural climate forcing dominated, and more droughts in the twentieth century when anthropogenic forcing dominated. Coherent drought was the only spatial pattern of precipitation significantly associated with explosive low-latitude volcanic eruptions. The increased coherent droughts and dipole patterns in the twentieth century support the findings of previous modeling studies that the tropospheric aerosols and human-induced land cover changes play important roles in the changes of summer rainfall over eastern China. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. This paper is a contribution to the AMIP-CMIP Diagnostic Sub-project on General Circulation Model Simulation of the East Asian Climate, coordinated by W.-C. Wang.  相似文献   

4.
与华北地区春季降水量异常关联的大气环流异常   总被引：13，自引：1，他引：12  
华北地区的春旱极大地影响着农作物的播种和生长.因此,尽管华北地区的春季1降水量没有夏季降水量那么多,但它的变化规律及其原因也是一个非常值得研究的问题.在本文中,我们指出,相对平均值而言,华北地区春季降水量的年际变化相当大.早年降水量的变化幅度相对较小,而降水多的年份之间降水量却有相当大的变化.进而,我们分析了在年际变化时间尺度上,与华北地区春季降水异常相关联的大尺度大气环流异常.发现在华北春季降水多时,东亚地区上空在整个对流层中存在一反气旋式环流异常,即与季节演变特征相符,而在热带地区存在与季节演变相反的环流异常.东亚地区上空这种反气旋式环流使得东亚大槽偏东、偏弱,并使得在我国东部地区出现南风异常,这种南风异常一直达到华北地区,为华北地区的降水提供有利条件.此外,反气旋式异常随高度向西斜,也为扰动的发展提供了有利的环流背景.本文对对流层高层经向风的分析结果表明,与华北春季降水密切相关的东亚地区反气旋式环流异常和南北风异常与出现在北半球中纬地区的波列有关系,但关于该波列产生的原因却有待进一步的研究.    相似文献   

5.
The northern fringe of the Asian summer monsoon region (NASM) in China refers to the most northwestern extent of the Asian summer monsoon. Understanding the characteristics and underlying mechanisms of drought variability at long and short time-scales in the NASM region is of great importance, because present and future water shortages are of great concern. Here, we used newly developed and existing tree-ring, historical documentary and instrumental data available for the region to identify spatial and temporal patterns, and possible mechanisms of drought variability, over the past two millennia. We found that drought variations were roughly consistent in the western (the Qilian Mountains and Hexi Corridor) and eastern (the Great Bend of the Yellow River, referred to as GBYR) parts of the NASM on decadal to centennial timescales. We also identified the spatial extent of typical multi-decadal GBYR drought events based on historical dryness/wetness data and the Monsoon Asia Drought Atlas. It was found that the two periods of drought, in AD 1625–1644 and 1975–1999, exhibited similar patterns: specifically, a wet west and a dry east in the NASM. Spatial characteristics of wetness and dryness were also broadly similar over these two periods, such that when drought occurred in the Karakoram Mountains, western Tianshan Mountains, the Pamirs, Mongolia, most of East Asia, the eastern Himalayas and Southeast Asia, a wet climate dominated in most parts of the Indian subcontinent. We suggest that the warm temperature anomalies in the tropical Pacific might have been mainly responsible for the recent 1975–1999 drought. Possible causes of the drought of 1625–1644 were the combined effects of the weakened Asian summer monsoon and an associated southward shift of the Pacific Intertropical Convergence Zone. These changes occurred due to a combination of Tibetan Plateau cooling together with more general Northern Hemisphere cooling, rather than being solely due to changes in the sea surface temperature of the tropical Pacific. Our results provide a benchmark for comparing and validating paleo-simulations from general circulation model of the variability of the Asian summer monsoon at decadal to centennial timescales.  相似文献   

6.
近年来,在全球变暖的背景下,极端气候事件特别是极端降水事件,发生频率愈发上升。本文使用美国气候预测中心提供的逐日降水资料,统计分析了1979—2018年期间欧亚大陆各个子区域极端降水事件的时空变化特征。结果表明:1)从气候态的空间分布特征来看,南欧、南亚、东南亚、东亚地区为欧亚大陆全年总降水量高值区,同时也是极端强降水频发地区;而东亚地区青藏高原、中国中西部至蒙古一带,南亚地区印度次大陆以及中亚、西亚等地的部分地区则是连续性干旱事件的高频区,极端强降水事件发生频次较少;2)在21世纪初之后,东南亚、南亚、东亚、北亚、西亚和南欧这6个地区的全年总降水量发生年代际增加,且在研究时段呈显著增加趋势。在过去近40 a,南亚、东亚和中亚的RX1day(日最大降水量)、RX5day(连续5 d最大降水量)、中雨日数(R10mm)、大雨日数(R20mm)自20世纪90年代中期年代际增加,且呈长期增加趋势。南亚、北亚、东亚、中亚这4个地区的最大连续干旱日数在20世纪80年代初显著增加,但长期趋势并不显著。需要指出的是,自2014年起极端强降水事件在东南亚、南亚和东亚地区持续增多,而连续性干旱事件在北欧地区持续增多。  相似文献   

7.
亚洲夏季风的年际和年代际变化及其未来预测   总被引：31，自引：12，他引：19  
本文是对我们近五年在亚洲夏季风年代际与年际变率及其未来预测方面研究的一个综述.主要包括下列三个问题:(1)根据123年中国夏季降水资料和印度学者的分析,检测出亚洲夏季风具有明显的年代际尺度减弱,这种年代际变化使中国东部(包括东亚)和南亚夏季降水的格局在过去60年中发生了明显变化.在东亚,从1970年代后期开始,主要异常雨带有不断南移的趋势,结果造成了南涝北旱的降水分布,这主要受到60～80年年代际振荡的影响.青藏高原前冬和春季积雪的年代际减少与热带中东太平洋海表温度的年代际增加是东亚降水型改变的主要原因,这是通过减弱亚洲地区夏季海陆温差与夏季风强度而实现的.未来亚洲夏季风的预测表明,东亚夏季风和南亚夏季风对气候变暖有十分不同的响应.东亚夏季风在本世纪将增强,雨带北推,尤其在2040年代之后;而南亚夏季风环流将继续减弱.这种不同的变化是由于两者对高低层海陆热力差异的不同响应造成.(2)年际尺度的变率在亚洲夏季风区主要表现为2年与4～7年的振荡.本文着重分析了2年振荡(TBO)形成的过程、机理及其对东亚降水的影响.对TBO-海洋机理进行了具体的改进,说明了东亚夏季风降水深受TBO影响的原因,尤其是阐明了长江型(YRV) TBO和淮河型(HRV) TBO的特征及其形成的循环过程.(3)在总结亚洲夏季风时期遥相关型的基础上,本文提出了季节内和年际尺度的低空遥相关型:即西北太平洋季风的遥相关型与印度“南支”和“北支”遥相关型.它们基本上反映了沿低空夏季风强风速带Rossby波群速度传播的结果.据此可以根据西北太平洋和印度夏季风的变化分别预测中国梅雨和华北雨季来临和降水异常.最后研究还表明,在本世纪亚洲夏季风可能更显著地受到人类活动造成的全球变暖的影响,未来的亚洲夏季风活动是人类排放的CO2引起的全球变暖与自然变化(海洋和陆面过程(积雪))共同作用的结果.  相似文献   

8.
The reliability of CRU05 rainfall dataset produced by Climatic Research Unit, University of East Anglia is examined against 22 station observations in the northern China. While this dataset has high spatial resolution and long temporal coverage, comparison with station data suggests that it only has higher quality in the last 70 years in the western China. When using this dataset to analyze rainfall variability over the northern China, significant oscillations with periods of 3, 10, and 30 yr are found, with interannual and interdecadal oscillations being the major characteristics of drought and flood events in the region in the last 100 years. Using EOF and REOF analysis, 10 divisions with coherent rainfall variations have been identified, including (i) central Asia and north of Xinjiang, (ii) North China and east of Northwest China,(iii) north and middle of Mongolia, (iv) Hexi Corridor and west of Mongolia, (v)east of the Heilong River,(vi) north of Da Hinggan Mountains, (vii) north of Central Asia, (viii) south of Xinjiang and the Qinghai-Tibetan Plateau, (ix) south of Northeast China, and (x) north of Altay Mountains. Results suggest that the pronounced feature of drought in the arid and semi-arid areas of northern China is not isolated. Of course, it is consistent with rainfall variations in the arid areas of Mongolia and Central Asia. In addition,by analyzing prominent oscillations observed in the last several decades, the trends of rainfall variations over the region in the future 10-15 years are discussed.  相似文献   

9.
Northern Hemisphere circulations differ considerably between individual El Niño-Southern Oscillation events due to internal atmospheric variability and variation in the zonal location of sea surface temperature forcing over the tropical Pacific Ocean. This study examines the similarities between recent Northern Hemisphere droughts associated with La Niña events and anomalously warm tropical west Pacific sea surface temperatures during 1988–1989, 1998–2000, 2007–2008 and 2010–2011 in terms of the hemispheric-scale circulations and the regional forcing of precipitation over North America and Asia during the cold season of November through April. The continental precipitation reductions associated with recent central Pacific La Niña events were most severe over North America, eastern Africa, the Middle East and southwest Asia. High pressure dominated the entire Northern Hemisphere mid-latitudes and weakened and displaced storm tracks northward over North America into central Canada. Regionally over North America and Asia, the position of anomalous circulations within the zonal band of mid-latitude high pressure varied between each La Niña event. Over the northwestern and southeastern United States and southern Asia, the interactions of anomalous circulations resulted in consistent regional temperature advection, which was subsequently balanced by similar precipitation-modifying vertical motions. Over the central and northeastern United States, the spatial variation of anomalous circulations resulted in modest inter-seasonal temperature advection variations, which were balanced by varying vertical motion and precipitation patterns. Over the Middle East and eastern Africa, the divergence of moisture and the advection of dry air due to anomalous circulations enhanced each of the droughts.  相似文献   

10.
Northeast China(NEC) is China’s national grain production base, and the local precipitation is vital for agriculture during the springtime. Therefore, understanding the dynamic origins of the NEC spring rainfall(NECSR) variability is of socioeconomic importance. This study reveals an interdecadal change in the atmospheric teleconnections associated with the NECSR during a recent 60-year period(1961–2020). Before the mid-1980s, NECSR had been related to a Rossby wave train that is coupled with ex...  相似文献   

11.
Droughts in the East Asian region (105–150°E, 20–50°N) are quantified using the effective drought index (EDI) over a period of 43 years, from 1962 to 2004, and the East Asian region was classified into six subregions on the basis of similarity in drought climate: (D1) South China; (D2) lower region of the Yangtze River, South Korea, and Central/South Japan; (D3) Central China and North Korea; (D4) Northwest China and middle region of the Yangtze River; (D5) North China; and (D6) Northeast China and North Japan. The EDI time series was then summarized for the different drought subregions and a drought map was created that shows the spatiotemporal characteristics of regional drought occurrence in East Asia. The map shows that in subregions, D1, D2, D3, D4, D5, and D6, there were 50 (11.63 per decade), 36 (8.37 per decade), 30 (6.98 per decade), 28 (6.51 per decade), 29 (6.74 per decade), and 33 (7.67 per decade) drought occurrences, respectively. The most common characteristic of droughts in the subregions is that short-term droughts (<200 days) which mainly occur in spring and summer, whereas long-term droughts (≥200 days) mainly occur in autumn and winter. D1 shows the highest frequency of short-term droughts. Short-term droughts occur more frequently than long-term droughts in D2 and D3, but D4 and D6 showed a higher frequency of long-term droughts than short-term droughts. D5 showed a similar frequency of short- and long-term droughts. Drought onset dates are evenly distributed throughout the year for D1, D2, and D3, but distributed mostly in spring and summer in D4, D5, and D6. All the differences are linked to variations in the precipitation cycle of each subregion. In terms of annual variations in drought occurrence, D2 showed weakening droughts (the annual lowest EDI shows a positive trend), whereas the other subregions showed intensifying droughts (the annual lowest EDI shows a negative trend). The greatest intensifying trend was observed in D5, followed by D3, D6, D4, and D1.  相似文献   

12.
近500年的厄尔尼诺事件   总被引：32，自引：2，他引：32  
王绍武 《气象》1989,15(4):15-20
根据南美洪水、澳大利亚干旱、印度尼西亚干旱、登陆我国台风次数、东亚冷夏,用我国旱涝恢复的南方涛动指数,用北美树木年轮恢复的南方涛动指数,用北美树木年轮恢复的南方涛动指数等资料初步确定了1470年以来的厄尔尼诺事件。  相似文献   

13.
Extreme precipitation events in the upper Yangtze River Valley (YRV) have recently become an increasingly important focus in China because they often cause droughts and floods. Unfortunately, little is known about the climate processes responsible for these events. This paper investigates factors favorable to frequent extreme precipitation events in the upper YRV. Our results reveal that a weakened South China Sea summer monsoon trough, intensified Eurasian-Pacific blocking highs, an intensified South Asian High, a southward subtropical westerly jet and an intensified Western North Pacific Subtropical High (WNPSH) increase atmospheric instability and enhance the convergence of moisture over the upper YRV, which result in more extreme precipitation events. The snow depth over the eastern Tibetan Plateau (TP) in winter and sea surface temperature anomalies (SSTAs) over three key regions in summer are important external forcing factors in the atmospheric circulation anomalies. Deep snow on the Tibetan Plateau in winter can weaken the subsequent East Asian summer monsoon circulation above by increasing the soil moisture content in summer and weakening the land–sea thermal contrast over East Asia. The positive SSTA in the western North Pacific may affect southwestward extension of the WNPSH and the blocking high over northeastern Asia by arousing the East Asian-Pacific pattern. The positive SSTA in the North Atlantic can affect extreme precipitation event frequency in the upper YRV via a wave train pattern along the westerly jet between the North Atlantic and East Asia. A tripolar pattern from west to east over the Indian Ocean can strengthen moisture transport by enhancing Somali cross-equatorial flow.  相似文献   

14.
1959-2003年青海省干湿变化分析   总被引：1，自引：0，他引：1  
利用青海省1959-2003年气象资料,计算了修正的Palmer干旱指数,并对其进行了分析。结果表明：在青海省旱涝监测中,PDSI指数反映旱涝程度更为客观;青海省的干旱主要以轻旱为主;夏秋季年际干湿交替较冬春季频繁,变化振幅也较大;秋季青海省干旱化倾向最为严重,冬春季出现轻旱几率最大。另外,春季干旱总面积在减小;夏季轻旱面积增加,而中旱、重旱面积在减小;秋冬季重旱面积在增加。  相似文献   

15.
It is not clear how the frequency and amplitude of droughts have varied over the past 500 years in China, as the instrumental record is too short to identify centennial-scale trends. While the Monsoon Asia Drought Atlas (MADA) provides some insights into past drought patterns, its accuracy in eastern China remains uncertain. A comparison of the MADA and Chinese historical documents indicates that the MADA alone cannot effectively represent dryness and wetness in eastern China, so it is not appropriate to use the MADA in this region.  相似文献   

16.
基于1960—2019年中国东北地区108个台站逐日降水资料、JRA-55再分析资料和Hadley中心海温数据,分析了东北地区春季极端连续无雨日的年际变化特征及其与前冬北太平洋地区大气环流和海表温度的关系。研究表明,东北地区春季极端连续无雨日集中在3—4月。当3—4月极端连续无雨日偏多时,贝加尔湖地区存在异常高压,东北地区受偏北气流影响,局地水汽辐散。进一步分析发现,东北地区3—4月极端连续无雨日与前冬1—2月北太平洋地区偶极型海平面气压存在密切联系。该大气模态可以引起同期北太平洋海温呈现出马蹄形异常分布并持续到3—4月。在3—4月,海温异常可以通过改变北太平洋上空的经向温度梯度,引起东亚到北太平洋地区的西风变化,进而有利于贝加尔湖地区出现异常高压。另一方面,海温异常还会增强北半球中纬度的波列活动,东传的波列也可以增强贝加尔湖地区的高压。上述异常环流为东北地区极端连续无雨日的增加提供了有利背景条件。留一交叉验证结果显示,前冬1—2月北太平洋地区偶极型海平面气压可作为东北春季极端连续无雨日的潜在预测因子。  相似文献   

17.
近百年东亚冬季气温及其大气环流变化型态   总被引：7，自引：2，他引：5  
范可  刘辉 《大气科学》2013,37(2):383-394
利用最新20世纪近百年再分析气象资料,研究近百年东亚冬季气温变化型及其相关的大气环流型态.结果表明近百年内东亚冬季气温主要有两种变化型:第一是东亚西南与东北相反气温变化型,表现在40°N以南及105°E以西地区(西南地区)气温变化与40°N以北及105°E以东地区(东北地区)变化相反;第二是40°N以南气温一致变化型.与第一种气温变化型耦合的大气模态是500hPa欧亚型遥相关、西伯利亚高压及北大西洋涛动.当欧亚型遥相关负位相,北大西洋涛动正位相及西伯利亚高压减弱时,有利于蒙古和我国105° E以东的区域增温而我国西南地区和青藏高原降温,反之亦然.第二种气温变化型耦合大气模态是500hPa西太平洋型遥相关,北太平洋涛动.当西太平洋型遥相关及北太平洋涛动处于正位相时(北太平洋北负南正),东亚40°N以南地区增温,东亚40°N以北地区降温.耦合的大气模态的型态差异,影响各阶段气温的年际变化.近一百年中,欧亚型遥相关和北大西洋涛动在1984～2010期间的型态最显著,是20世纪80年代东亚显著增暖的原因之一.研究还发现20世纪中期后东亚气温的年际变化与极地环流的变化联系紧密,表现在西伯利亚高压范围东扩并与极地环流联系,也是近百年气温趋势上升的一个原因.  相似文献   

18.
The carbon monoxide (CO) concentrations observed at Mt. Waliguan in China (WLG), Ulaan Uul in Mongolia (UUM), Tae-ahn Peninsula in Korea (TAP) and Ryori in Japan (RYO) were analysed between 1991 and 2008. The average annual concentration of CO, a toxic air pollutant, was the highest at TAP (235±44 ppb), followed by RYO (169±35 ppb), UUM (154±27 ppb) and WLG (138±24 ppb). These data obtained in East Asia were also compared with CO data from Mauna Loa, Hawaii. CO tends to be highest in spring and lowest in summer in East Asia, with the exception of WLG. TAP had the highest CO concentrations in all seasons compared with WLG, UUM and RYO, and displays a wide short-term variability in concentration. This is caused by large-scale air pollution owing to its downwind location, close to continental East Asia. CO concentrations observed at TAP were analysed as follows: according to the origin of the isentropic backward trajectory and its transport passage; as continental background airflows (CBG); regionally polluted continental airflows (RPC); oceanic background airflows (OBG); and partly perturbed oceanic airflows (PPO). The high concentrations of CO at TAP are because of the airflow originating from the East Asian continent, rather than the North Pacific. RPCs, which pass through eastern China, appear to have high CO concentrations in spring, autumn and winter. It is noteworthy that the overall trend at TAP does not show an increase despite the fact that energy use in China approximately doubled from 1991 to 2008. OBGs, however, are affected by North Pacific air masses with low CO concentrations in summer.  相似文献   

19.
Characteristics of the drought periods which occurred in North Africa,Middle East,Middle Asiaand Northwest China were studied based on the analysis of rainfall data from 1870—1990.It is foundthat the drought periods first started in North Africa and expanded eastward to Northwest Chinathrough Middle East and Middle Asia in about 27.5 years.And then a new teleconnection pattern of30—50 day low-frequency oscillation which is associated with the droughts over the Africa-Asia Con-tinent was discovered.Finally,a hypothesis is proposed based on the statistical results that the east-ward expansion of drought periods may be caused by the occurrence of giant earthquakes(Ms>6.0)which have a tendency to shift eastward from North Africa to Northwest China in about 27.75 years.  相似文献   

20.
Based on the past 200-year graded data of dryness/wetness in eastern China (24 stations), five phases to show the floods and droughts have been objectively divided by using the approach of cluster analysis of a sequential sample. The characteristics of flood/drought evolution have been described and explained. It is concluded that the floods or droughts occurred more often for the past two centuries, and the normal phase was seldom seen in eastern China. The transitions between floods and droughts are frequently of jumping feature. The extent and the frequency of serious drought or heavy flood in eastern China tended to expand and increase significantly in the last 50 years. Finally, by using the Walsh power spectrum, the periodicity of dryness/wetness graded series has been analysed. It is found that there exist the 2－9 year high-frequency fluctuations in eastern China.  相似文献   

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