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1.
华北夏季旱涝与同期500 hPa高度异常 总被引：4，自引：2，他引：2
采用中国气象局整编的月降水量、500hPa月平均高度场资料,利用相关、合成和奇异值分解等方法分析了华北夏季旱涝的时空分布特征及其环流异常特征,得到了500hPa高度场与同期降水的主要耦合模态。结果表明：华北旱涝年,北半球环流从高纬到低纬都存在显著的异常,其中显著区域有4个：北非到西亚的低纬地区、青藏高原地区、乌拉尔山东北部及加拿大东部。环流的异常变化与华北夏季降水的异常变化趋势较一致。亚洲地区由高纬到低纬,涝年环流异常表现为“ - ”分布;旱年为“- -”分布。 相似文献
2.
西北东部夏季干湿演变及环流特征 总被引：2，自引：1，他引：2
选取中国西北东部1960--2004年33个台站夏季（6—8月）逐日降水资料和北半球NECP／NCAR500hPa高度场再分析资料，首先统计了中国西北东部逐年夏季总降水量和无雨日数，并根据它们呈显著负相关的特点，定义了无雨日数一降水均一化干湿指数，然后对干湿指数场进行了EOF分解，探讨了西北东部夏季干湿异常的演变特征，同时对干湿异常年份进行了500hPa高度距平场合成分析。结果发现：一致性异常特征是西北东部夏季干湿指数的最主要的空间异常模态；西北东部近45年来的变干趋势是明显的；新疆脊偏弱、东亚大槽偏浅是西北东部夏季湿年同期500hPa高度场特征，而新疆脊偏强、东亚大槽偏深是干年同期500hPa高度场特征；乌拉尔山脊线偏西、东亚大槽偏浅是湿年前期12月高度场特征；乌拉尔山脊线偏东、东亚大槽偏深是干年前期12月高度场特征。冬季12月500hPa高度场环流特征是预测下年夏季干湿特征不容忽视的指标。 相似文献
3.
Global hydroclimatic changes from 1950 to 2018 are analyzed using updated data of land precipitation, streamflow, and an improved form of the Palmer Drought Severity Index. The historical changes are then compared with climate model-simulated response to external forcing to determine how much of the recent change is forced response. It is found that precipitation has increased from 1950 to 2018 over mid-high latitude Eurasia, most North America, Southeast South America, and Northwest Australia, while it has decreased over most Africa, eastern Australia, the Mediterranean region, the Middle East, and parts of East Asia, central South America, and the Pacific coasts of Canada. Streamflow records largely confirm these precipitation changes. The wetting trend over Northwest Australia and Southeast South America is most pronounced in austral summer while the drying over Africa and wetting trend over mid-high latitude Eurasia are seen in all seasons. Coupled with the drying caused by rising surface temperatures, these precipitation changes have greatly increased the risk of drought over Africa, southern Europe, East Asia, eastern Australia, Northwest Canada, and southern Brazil. Global land precipitation and continental freshwater discharge show large interannual and inter-decadal variations, with negative anomalies during El Niño and following major volcanic eruptions in 1963, 1982, and 1991; whereas their decadal variations are correlated with the Interdecadal Pacific Oscillation (IPO) with IPO’s warm phase associated with low land precipitation and continental discharge. The IPO and Atlantic multidecadal variability also dominate multidecadal variations in land aridity, accounting for 90 % of the multidecadal variance. CMIP5 multi-model ensemble mean shows decreased precipitation and runoff and increased risk of drought during 1950–2018 over Southwest North America, Central America, northern and central South America (including the Amazon), southern and West Africa, the Mediterranean region, and Southeast Asia; while the northern mid-high latitudes, Southeast South America, and Northwest Australia see increased precipitation and runoff. The consistent spatial patterns between the observed changes and the model-simulated response suggest that many of the observed drying and wetting trends since 1950 may have resulted at least partly from historical external forcing. However, the drying over Southeast Asia and wetting over Northwest Australia are absent in the 21st century projections.
相似文献4.
本文运用月降水量、500hPa、100hPa月平均高度场和海平面气压场，在对50a华北夏季旱涝等级重新评定的基础上，分析了与华北夏季旱涝年对应的环流异常特征。结果表明华北旱涝年，对应整个北半球上各层都存在显著的环流异常变化。旱年500hPa环流异常使得极涡偏心，相应乌拉尔山和北美的气候槽偏强；中纬度位于华北的平均槽东移到朝鲜日本一带，而西部脊东移控制华北；低纬西太平洋副高偏东，印度低压槽偏弱。涝年则相反。在海平面气压场上，除了在与高层对应的显著异常区有相应变化外，在我国东部大陆大部及赤道中东太平洋上也有一显著的异常区，证实夏季风和KNSO与华北旱涝存在密切的联系。在100hPa高度场旱涝年环流差异主要表现为南亚高压南北界的位置变化。 相似文献
5.
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.
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6.
根据2008年1月我国南方发生的持续严重雨雪冰冻灾害、1998年长江流域的特大洪涝灾害和2009/2010年冬季云南的极端干旱灾害的分析结果,再次强调指出,对于一些小概率的极端天气气候事件的发生,大气环流系统的组合性异常起着极其重要的作用。对于2008年的严重雨雪冰冻灾害的发生,多个大气环流系统的组合性异常包括:乌拉尔山阻塞高压和贝加尔湖-巴尔喀什湖的横槽,这为不断有冷空气从西路向南爆发提供了条件;东亚和日本地区的高度正异常使得北方冷空气的势力不是很强,适于锋面在我国南岭及其以北地区较长时间停留,为持续降水确立了背景;西太平洋副高偏强和偏西也对冷空气的向南推进起了阻挡作用;印-缅槽的持续偏强和西太平洋副高的偏强共同使暖湿空气源源不断地输送到华南地区,有利持续降水的发生,为冰冻造成了条件。对于1998年夏季长江流域的特大洪涝的发生,多个环流系统的异常包括:夏季西南季风涌的活动,西太平洋副热带高压活动,北方冷空气活动和青藏高原对流系统东传的共同作用。对于2009/2010年冬季云南的极端干旱灾害的发生,多个环流系统的异常包括:对流层高层中东地区副热带西风急流减弱,影响Rossby波的活动,不利于青藏高原-孟加拉湾槽的建立;西太平洋副热带高压偏强、位置略为偏南,对低层水汽输入云南起到抑制作用;NAO的负异常所导致的遥相关波列异常,使得东亚北方冷空气活动偏东,不易到达云南地区,还使得南支槽偏弱,暖湿气流也不易到达云南地区。ENSO虽然对中国天气气候变化有相当重要的影响,但并非每次异常天气气候事件的发生都是它的直接影响。对于ENSO影响必须具体分析,才能决定它在异常事件、特别是极端天气气候事件中的确切作用。 相似文献
7.
全球陆地年降水量与ENSO关系的初步研究 总被引：12，自引：0，他引：12
用全球陆地月降水资料（PREC／L），研究了1948－2000年期间的ENSO事件与全球陆地年降水量的关系，对全盛分析的结果进行了蒙特卡洛模拟经验。结果表明，暖事件年全球陆地年降水量大范围地明显减小，显著的地区是：赤道西太平洋区，中国的华北，赤道中美洲区，孟加拉湾北部及尼泊尔，东澳大利亚区，印度西部及巴基斯坦南部，勒拿河以东地区，西欧及南极的威尔克斯等区域。在暖事件年，陆地年降水量增加地区不多，主要是南美的智利和阿根廷，东非索马里，肯尼亚和坦桑亚，中东的土耳其，伊拉克及伊朗，北非的利比亚和阿尔及利亚，西南非的纳米比亚及非洲南部的博茨瓦纳和津巴布韦。统计检验表明，暖事件年全球陆地年降水量减少的面积比降水量增加的面积要大，而且更为显著，将本文结果与早期的研究结果进行了比较，研究还指出，ENSO的年代际变化对上述地区降水的年代际变化影响不明显。但是80年代以后的暖事件对东澳大利亚干旱，中国的华北的干旱的影响比80年代前的影响更大。 相似文献
8.
利用1948—2011年NCEP/NCAR月平均再分析资料和1951—2010年我国160站降水量资料,研究了冬季亚洲—太平洋区域的大气遥相关及其与东亚冬季风和降水的关系。结果表明:冬季在亚洲—西太平洋与中、东太平洋中低纬度对流层上层扰动温度之间存在类似于夏季的亚洲—太平洋涛动 (APO) 现象,即当东亚中低纬度对流层中、上层偏暖时,中东太平洋中低纬度对流层中上层温度偏冷,反之亦然。冬季APO可以反映冬季亚洲—太平洋东西向热力差异强度变化,与夏季相比,冬季APO遥相关在亚洲的中心位置略偏南、偏东,且冬季APO与大气环流关系与夏季也有所不同;当冬季APO指数偏高时,对流层上层东亚大槽位置偏西,而东亚热带地区的高压向北伸展,导致我国南方对流层为深厚的异常反气旋系统所控制,此时南方地区对流层低层盛行异常的偏东北气流,并伴随水汽辐散和异常下沉运动,南方降水偏少;冬季APO指数与ENSO有紧密联系。 相似文献
9.
Aerosols make a considerable contribution to the climate system through their radiative and cloud condensation nuclei effects, which underlines the need for understanding the origin of aerosols and their transport pathways. Seasonal distribution of mineral dust around the globe and its correlation with atmospheric circulation is investigated using satellite data, and meteorological data from ECMWF. The most important sources of dust are located in North Africa, the Middle East and Southwest Asia with an observed summer maximum, and East Asia with a spring peak. Maximum dust activity over North Africa and the Middle East in summer is attributed to dry convection associated with the summertime low-pressure system, while unstable weather and dry conditions are responsible for the spring peak in dust emission in East Asia. Intercontinental transport of mineral dust by atmospheric circulation has been observed, including trans-Atlantic transport of North African dust, trans-Pacific transport of Asian dust, and transport of dust from the Middle East across the Indian Ocean. The extent of African dust over the Atlantic Ocean and its latitudinal variation with season is related to the large-scale atmospheric circulation, including seasonal changes in the position of the intertropical convergence zone (ITCZ) and variation of wind patterns. North African aerosols extend over longer distances across the North Atlantic in summer because of greater dust emission, an intensified easterly low level jet (LLJ) and strengthening of the Azores-Bermuda anticyclonic circulation. Transport of East Asian aerosol is facilitated by the existence of a LLJ that extends from East Asia to the west coast of North America. 相似文献
10.
以西北地区东部的17个代表站1470—2008年的旱涝等级资料和1958—2015年5—9月气象站降水量数据为基础，建立了546年中国西北地区东部旱涝等级序列，采用经验正交函数分解、滑动t检验等统计方法，对其干湿演变规律进行分析，详细讨论了546年极端干旱事件及干旱持续性特征。结果表明:旱涝等级资料能够较好地反映西北地区东部干旱变化的时、空特征；在百年尺度上，20世纪发生旱、偏旱最为频繁，且高值区位于宁夏及陕北；干旱尺度因子的空间分布表明宁夏东部及陕北地区的干旱持续性相对较强，陇南及陕西南部地区的干旱持续性较差；空间范围较大且强度较大的重大干旱事件对干旱的持续发生起重要作用，历史上发生在1470—1500年和1910—1940年的两次西北地区东部百年甚至两百年一遇的极端干旱事件，对该地区干旱持续性的影响较为显著。 相似文献
11.
Spatial and Temporal Variations of Rainfall over Northern Asia in the Last 100 Years and Their Possible Changes in the Future 
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下载免费PDF全文 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
12.
The Response of Anomalous Vertically Integrated Moisture Flux Patterns Related to Drought and Flood in Southern China to Sea Surface Temperature Anomaly 下载免费PDF全文
下载免费PDF全文 With the extreme drought (flood) event in southern China from July to August in 2022 (1999) as the research object, based on the comprehensive diagnosis and composite analysis on the anomalous drought and flood years from July to August in 1961-2022, it is found that there are significant differences in the characteristics of the vertically integrated moisture flux (VIMF) anomaly circulation pattern and the VIMF convergence (VIMFC) anomaly in southern China in drought and flood years, and the VIMFC, a physical quantity, can be regarded as an indicative physical factor for the "strong signal" of drought and flood in southern China. Specifically, in drought years, the VIMF anomaly in southern China is an anticyclonic circulation pattern and the divergence characteristics of the VIMFC are prominent, while those are opposite in flood years. Based on the SST anomaly in the typical draught year of 2022 in southern China and the SST deviation distribution characteristics of abnormal draught and flood years from 1961 to 2022, five SST high impact areas (i.e., the North Pacific Ocean, Northwest Pacific Ocean, Southwest Pacific Ocean, Indian Ocean, and East Pacific Ocean) are selected via the correlation analysis of VIMFC and the global SST in the preceding months (May and June) and in the study period (July and August) in 1961-2022, and their contributions to drought and flood in southern China are quantified. Our study reveals not only the persistent anomalous variation of SST in the Pacific and the Indian Ocean but also its impact on the pattern of moisture transport. Furthermore, it can be discovered from the positive and negative phase fitting of SST that the SST composite flow field in high impact areas can exhibit two types of anomalous moisture transport structures that are opposite to each other, namely an anticyclonic (cyclonic) circulation pattern anomaly in southern China and the coastal areas of east China. These two types of opposite anomalous moisture transport structures can not only drive the formation of drought (flood) in southern China but also exert its influence on the persistent development of the extreme weather. 相似文献
13.
Drought events have become more frequent and intense over East Asia in recent decades, leading to hugesocioeconomic impacts. Although the droughts have been studied extensively by cases or for individual regions, theirleading variability and associated causes remain unclear. Based on the Standardized Precipitation Evapotranspiration Index(SPEI) and ERA5 reanalysis product from 1979 to 2020, this study evealuates the severity of spring droughts in East Asiaand investigates their variations and associated drivers. The results indicate that North China and Mongolia have ex perienced remarkable trends toward dryness during spring in recent decades, while southwestern China has witnessed anopposite trend toward wetness. The first Empirical Orthogonal Function mode of SPEI variability reveals a similarseesawing pattern, with more severe dryness in northwestern China, Mongolia, North China, South Korea, and Japan butincreased wetness in Southwestern China and southeast Asia. Further investigation reveals that the anomalously dry (wet)surface in North (Southwestern) China is significantly associated with anomalously high (low) temperature, less (more)precipitation, and reduced (increased) soil moisture during the previous winter and early spring, regulated by an anomalousanticyclone (cyclone) and thus reduced (increased) water vapor convergence. The spring dry-wet pattern in East Asia isalso linked to cold sea surface temperature anomalies in the central-eastern Pacific. The findings of this study haveimportant implications for improving the prediction of spring drought events in East Asia. 相似文献
14.
2001年全球重大气候事件概述 总被引：1，自引：0，他引：1
全球气候仍持续偏暖。亚洲大部出现异常冷冬，许多地区遇到数十年未见的风雪严寒；美国冬季也连续遭受暴风雪袭击。东亚、南亚、中亚有西亚发生了大范围的持久干旱，南亚、东南亚夏季暴雨频繁，造成严重洪涝灾害。欧洲、非洲及南美洲的许多国家和地区降水异常偏多，导致不同程度的洪水，俄罗斯西伯利亚地区发生百年不遇的大洪水。北大西洋飓风较常年显著偏多，西北太平洋台风也给沿海地区带来严重灾害。 相似文献
15.
Zengxin Zhang Qiang Zhang Xi Chen Jinchi Zhang Jianwei Zhou 《Theoretical and Applied Climatology》2011,104(3-4):337-347
Dryness and wetness variations in east China were analyzed using the standardized precipitation index (SPI) based on monthly precipitation data for 1961?C2005. A drying trend over North China was observed, which can be attributed to decreasing precipitation since the late 1970s. Moreover, NCAR/NCEP reanalysis dataset was used to investigate causes behind the drying trend in North China. The moisture flux on the regional boundaries of East China was calculated and a higher wavelet power spectrum for low-latitude boundaries (based on 20 and 25°N) occurred with significant periods in a 1-year band during 1961?C2005; however, since 1977, a significant 1-year period can no longer be detected on the northern boundary of South China (based on 35°N). The summer moisture flux during 1961?C1977, when compared to the same during 1978?C2005, has increased in East China. Good matches are found between moisture alterations and precipitation changes, and are also confirmed by the periods of moisture transport along different latitudes. The significant 1-year periods of moisture transport along the mid-latitude boundary (based on 35°N) have disappeared since 1977, which could be the causes behind the drought in North China. The disappearance of the significant 1-year band of moisture transport along the mid-latitude boundary (based on 35°N) in the late 1970s could be a result of the significantly decreased moisture transport in North China in summer. When southerly winds are weakened in East Asia, the southwesterly winds can only reach the south of the lower Yangtze River, which is the major cause behind the frequent summer droughts in North China in the recent years. 相似文献
16.
华北夏季降水与北半球环流及北太平洋海温关系的初步分析 总被引：10，自引：1，他引：10
在利用基于Z指数的判别方法确定华北地区严重旱涝年份的基础上，应用合成分析方法研究了严重旱涝年的环流形势并初步分析了华北夏季旱涝的成因。然后用相关分析研究方法找出了与华北地区夏季降水关系密切的海温关键区，即赤道中东太平洋地区和北太平洋中高纬地区。利用大气环流模式进行数值试验，进一步研究了两个区域海温影响华北降水的地理机制和相对重要性，得到了一些有意义的结果。最后初步探讨了影响华北夏季降水异常的可能物理机制。 相似文献
17.
2010年12月大气环流和天气分析 总被引：1，自引：0，他引：1
2010年12月环流特征如下:极涡强度偏弱,但在东亚向中纬度伸展,有利于冷空气积聚南下,北半球中高纬呈现4波型,副高位置偏东,南支槽活动略偏强.12月,全国平均降水量为18.0 mm,比常年同期偏多83.7%,而华北、黄淮中西部等地偏少8成以上,这些地区气象干旱发展.12月,全国平均气温为-3.8℃,比常年同期偏高0.... 相似文献
18.
利用1951～2011年中国台站观测的逐日降水、温度和美国NCEP/NCAR再分析月平均资料, 本文分析2010年秋、冬季(11月至次年2月)发生在华北地区持续性干旱的大气环流和海温异常特征, 并讨论了北极涛动(AO)和La Ni?a事件对此次干旱事件的影响。分析表明, 2010年发生在华北秋、冬季节的持续性干旱是叠加在降水减少气候趋势之上的一次极端干旱事件, 但本次极端干旱事件主要成因是受到同期较强的AO负位相和La Ni?a事件共同的影响。统计发现:AO的负位相有利于乌拉尔山阻塞高压维持和发展, 而贝加尔湖上空出现负位势高度异常, 导致东亚中高纬度经向环流加强和冷空气向南侵袭。AO负位相可导致贝加尔湖上空气压场偏低并影响冷空气的路径和强度, 进而间接地导致华北地区的干冷气候, 而同期La Ni?a的海温异常分布导致西北太平洋副热带高压偏弱偏南, 抑制了西太平洋水汽向华北地区输送, 从而直接导致该地区的干旱。由于2010年AO负指数和La Ni?a事件较历史干旱年份表现出较强和长时间持续性, 从而导致了锋面位置位于华北以南和华北本次的持续性干旱事件。 相似文献
19.
Anwesa Bhattacharya Rae Seol Park Young Cheol Kwon 《Asia-Pacific Journal of Atmospheric Sciences》2018,54(4):545-561
Over the North East Asia, extreme anomalous precipitation were observed in 2013 and 2014. During 2013 summer the precipitation was found to be higher (two standard deviation) than the climatological mean of the region; whereas during 2014, which was a borderline El Niño year, precipitation was found to be lower (one standard deviation). To understand the differences of these two anomalous years the Global/Regional Integrated Model system (GRIMs) has been used. The study found that low land-surface temperature and high sea-surface temperature over ocean caused a smaller land-sea contrast of surface temperature between East Asia and North West Pacific Ocean in 2014, which could have caused an eastward shift of mean monsoon circulation in that year compared to the circulation in 2013. Due to a change in the lower level circulation and wind field over East Asia the evaporation and moisture transport patterns became very different in those two years. In 2013, this study found high latent heat flux over Eastern China, which implies an increased surface evaporation over that region, and the moisture transported to the north by the mean monsoon circulation; whereas, there was no correlated transport of moisture to the North East Asia during 2014. The precipitable water over North East Asia has a stronger correlation with the latent heat flux over southern land region than that from Ocean region in the eastern side in both the years. A new approach is proposed to estimate the sub-grid scale hydrometeors from GRIMs, overestimated in the existing model. 相似文献
20.
利用我国地面606个气象观测台站1951—2006年的逐日降水量和平均气温资料, 使用《气象干旱等级》国家标准中推荐使用的综合气象干旱指数（IC）, 分析了近半个世纪以来全国及不同地区干旱变化情况。结果表明:总体而言, 全国干旱面积在近50年没有显著增加或减少的趋势, 但不同地区差异较大; 其中东北和华北地区干旱化趋势显著, 特别是20世纪90年代后期至21世纪初, 上述地区发生了连续数年的大范围严重干旱, 在近半个世纪中十分罕见; 东北、华北和西北地区东部的大部分地区在近50年中持续时间最长的干旱事件多发生在1980年以后的20多年中, 而且上述地区在近20多年来干旱发生得更加频繁。另外, 我国干旱化趋势最显著的地区与增暖幅度最大的地区有很大的一致性, 表明区域增暖在干旱变化中起着一定作用。 相似文献