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2009—2010年黔西南州特大干旱成因分析 总被引：1，自引：0，他引：1
2009年9月到2010年4月,黔西南州出现了特大干旱,是有气象资料记录以来最为严重的干旱灾害。该文利用黔西南8个县市台站的降水,NCEP/NCAR逐月再分析资料,分析从2009年9月到2010年4月持续干旱期间同期大气环流异常的特征。结果表明,持续干旱期间地面冷空气活动较常年偏东偏弱;西太平洋副热带高压脊线位置较常年偏西偏强;孟加拉湾的低值系统较常年偏弱,不活跃,使得暖湿气流不易北上;动力因子较常年同期偏弱,导致降水长时间持续偏少、气温持续偏高、蒸发量大,以上为黔西南州特大干旱发生的主要原因。 相似文献
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采用NCEP/NCAR再分析资料,分析了2008-2009年冬季河南干旱主要发生时段的大气环流状况及干旱缓解的大气环流背景,结果表明:干旱发展主要阶段,北极涛动处于正位相,欧亚中高纬度环流长时间维持阻塞形势,东亚冬季季风偏弱,印缅槽区被反气旋控制,西太平洋副高位置偏东,欧亚地区环流异常长时间维持导致河南发生干旱.2009年2月大气环流发生转变,北极涛动转为负位相,有利于高纬度冷空气南下,低纬度西太平洋副热带高压西进北抬向内地输送水汽,在冷空气与水汽条件配合下,河南2月份经历多次降水过程,旱情得以缓解. 相似文献
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用1961～2008年宁夏主要台站1月气温、降水量资料,NCEP/NCAR全球逐月2.5°×2.5°的高度场、风场资料和NCEP1973～2007年欧亚积雪等资料,分析了2008年1月宁夏持续连阴雪低温极端天气的主要成因。大气环流异常是导致2008年1月宁夏持续阴雪低温天气的主要原因;前期海温与欧亚积雪异常可能联合作用影响大气环流异常导致此次天气事件发生。欧亚积雪异常影响次年1月宁夏降水异常的可能机制是:积雪异常在积雪异常区激发波动,在30°～60°N通过波列的形式导致大气环流异常,从而影响宁夏1月降水异常。 相似文献
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利用ECMWF 1979～1993年2.5°×2.5°的网格点积雪深度资料、中国气象局整编的海平面气压、500 hPa高度场和NCEP再分析资料,探讨了欧亚冬季积雪异常对同期大气环流的影响.结果表明:(1) 欧亚中高纬冬季积雪面积与同期大气环流具有密切的联系:积雪面积为正(负)异常时,冬季500 hPa高度场对应正(负)欧亚-太平洋(简称EUP)遥相关型,东亚冬季风活动偏强(弱).(2)诊断结果表明,积雪异常与大气环流之间的密切联系在一定程度上反映了冬季积雪的异常分布可能对大气EUP遥相关型和东亚冬季风活动产生影响.(3)SVD分析得到的冬季积雪的异常分布与同期大气环流的耦合模态,证实了前面所得结果. 相似文献
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2006年夏季西南地区东部特大干旱及其大气环流异常 总被引：33，自引：1，他引：32
利用1959-2006年西南地区东部20个测站的逐日降水资料、NCEP/NCAR再分析资料以及国家气候中心提供的环流特征量资料,分析了2006年夏季西南地区东部特大干旱的时空分布及其同期大气环流的异常特征.结果表明,2006年夏季西南地Ⅸ东部少雨时段从6月中旬初开始一直持续到9月上旬中后期,达80多天,其中7月下旬中期到9月上旬中期降水尤其稀少.西南地区东部区域6、7、8月及整个夏季(6-8月)降水都偏少,降水指数显示2006年是西南地区东部1959年以来夏季降水最少的年份.2006年夏季西南地区特大干旱与大气环流异常有很大的关系,中高纬度环流及西太平洋副热带高压、西风带环流、南亚岛压、低层流场、水汽输送以及垂直运动等都持续异常.西太平洋副高异常偏北且偏西和副高异常偏弱且偏东时,两南地区东部都日,能出现严重干旱,2006年夏季属于副高控制性高温伏旱.西太平洋副高偏强偏北偏西,同时伴随南亚高压偏强偏东,西南地区东部在副高控制下,盛行下沉气流,同时也抑制了向该地的水汽输送,再加上西风带环流以及中高纬环流配置不利于冷空气南下,因而2006夏季西南地区东部少雨干旱.青藏高原热源偏弱,菲律宾附近地区对流非常活跃,是引起2006年夏季西太平洋副商偏强偏北偏西的重要原因. 相似文献
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2009年秋至2010年春我国西南地区严重干旱的成因分析 总被引：30，自引：10，他引：20
我国西南地区从2009年秋季到2010年春季发生了严重干旱,这次干旱无论持续时间和发生区域或降水减少程度都是近50年来所罕见的,因而本文利用ERA-40再分析资料和海温资料从热带西太平洋和热带印度洋热力异常对热带西太平洋和南亚上空大气环流的影响来分析了这次西南地区干旱发生的成因。分析结果表明:从2009年秋到2010年春季,热带西太平洋和热带印度洋处于升温状态,它使得热带西太平洋上空产生反气旋异常环流,造成了西南气流异常在我国东南沿海加强,而华南和华中地区上空处于低槽控制,因而在高原东部为槽后西北气流和下沉气流所控制,造成了从孟加拉湾来的水汽很难到达云贵高原,从而引起了此区域降水长期偏少。并且,分析结果还表明了中高纬度地区的环流异常对此次严重干旱也有重要影响。由于从2009年冬季到2010年春季中高纬度准定常行星波传播的极地波导偏强,而低纬波导偏弱,这导致波的E-P通量在60°N附近对流层和平流层为辐合,而在35°N附近对流层中、上层为辐散,从而引起纬向平均西风在60°N附近对流层和平流层减弱,而在35°N附近对流层中、上层加强,造成了北极涛动(AO)为很大的负值。由于AO为负值,东亚冬季冷空气活动强且路径偏东,使得到达西南地区冷空气偏弱,从而引起西南地区持续性严重干旱的发生。 相似文献
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基于广义平衡反馈方法的2009/2010年中国冬季气温异常型的诊断 总被引：5，自引：2，他引：3
利用中国160个台站和NCEP再分析资料,引入综合分析气候反馈的统计方法——广义平衡反馈方法(GEFA),结合EOF、相关合成分析,探讨2009/2010年中国冬季气温异常型的成因。结果表明:2009/2010年中国冬季气温出现的东北冷西南暖分布型与同期海温异常及其相联系的大气环流异常有密切的关系。其中赤道中东太平洋海温异常的El Ni?o型和赤道大西洋海温异常“正-负-正”三极型模态对2009/2010年中国冬季气温东北冷西南暖分布型有显著的强迫作用。上述海温异常型影响了大气环流异常,中高纬度地面偏北气流将冷空气输送到华北东北地区,致使该地区冬季气温偏低,同时中纬度西风增强,极地冷空气被迫盘踞在高纬,不能影响到西南地区,导致西南地区较常年更暖。 相似文献
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The few systematic international comparisons of climate policy strength made so far have serious weaknesses, particularly those that assign arbitrary weightings to different policy instrument types in order to calculate an aggregate score for policy strength. This article avoids these problems by ranking the six biggest emitters by far – China, the US, the EU, India, Russia, and Japan – on a set of six key policy instruments that are individually potent and together representative of climate policy as a whole: carbon taxes, emissions trading, feed-in tariffs, renewable energy quotas, fossil fuel power plant bans, and vehicle emissions standards. The results cast strong doubt on any idea that there is a clear hierarchy on climate policy with Europe at the top: the EU does lead on a number of policies but so does Japan. China, the US, and India each lead on one area. Russia is inactive on all fronts. At the same time climate policy everywhere remains weak compared to what it could be.
Policy relevance
This study enables climate policy strength, defined as the extent to which the statutory provisions of climate policies are likely to restrict GHG emissions if implemented as intended, to be assessed and compared more realistically across space and time. As such its availability for the six biggest emitters, which together account for over 70% of global CO2 emissions, should facilitate international negotiations (1) by giving participants a better idea of where major emitters stand relative to each other as far as climate policy stringency is concerned, and (2) by identifying areas of weakness that need action. 相似文献
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Stephen F. Wathen 《Climatic change》2011,108(1-2):333-356
This paper provides both a detailed history of environmental change in the Sierra Nevada over the past 1,800 years and evidence for climate teleconnections between the Sierra Nevada and Greenland during the late Holocene. A review of Greenland ice core data suggests that the magnitudes of abrupt changes in temperature and precipitation increased beginning c. 3,700 and 3,000 years ago, respectively. Precipitation increased abruptly 1,300 years ago. Comparing paleotemperature data from Cirque Peak, CA with paleoprecipitation data from Pyramid Lake, NV suggests that hot temperatures occurred at the beginnings of most severe droughts in the Sierra Nevada over the past 1,800 years. Severe fires and erosion also occurred at Coburn Lake, CA at the beginning of all severe droughts in the Sierra Nevada over the past 1,800 years. This suggests that abrupt climate change during the late Holocene caused vegetation and mountain slopes in some areas to be out of equilibrium with abruptly changed climates. Finally, the ending of drought conditions in Greenland coincided with the beginning of drought conditions in the Sierra Nevada over the past 1,800 years, perhaps as a result of the rapidly changed locations of the Earth??s major precipitation belts during abrupt climate change events. 相似文献
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Anthony H. McDaniel Chris A. Cantrell James A. Davidson Richard E. Shetter Jack G. Calvert 《Journal of Atmospheric Chemistry》1991,12(3):211-227
The infrared absorption cross-sections for eight commonly used halogenated methanes and ethanes have been measured as a function of temperature from 203 to 293 K. High resolution spectra (0.03 cm-1) have been used to derive integrated band strengths and peak cross-sections associated with the spectral features in the infrared region from 600 to 1500 cm-2. The values obtained in this study are compared to those from previous reports, and recommendations are made for uses in atmospheric sensing and radiative energy transfer models. The observed temperature dependence in the spectral features is also discussed. 相似文献
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Wind-driven, double-gyre, ocean circulation in a reduced-gravity, 2.5-layer, lattice boltzmann model
A coupled lattice Boltzmann （LB） model with second-order accuracy is applied to the reduced-gravity, shallow water, 2.5-layer model for wind-driven double-gyre ocean circulation. By introducing the secondorder integral approximation for the collision operator, the model becomes fully explicit. The Coriolis force and other external forces are included in the model with second-order accuracy, which is consistent with the discretization accuracy of the LB equation. The feature of the multiple equilibria solutions is found in the numerical experiments under different Reynolds numbers based on this LB scheme. With the Reynolds number increasing from 3000 to 4000, the solution of this model is destabilized from the anti-symmetric double-gyre solution to the subtropic gyre solution and then to the subpolar gyre solution. The transitions between these equilibria states are also found in some parameter ranges. The time-dependent variability of the circulation based on this LB simulation is also discussed for varying viscosity regimes. The flow of this model exhibits oscillations with different timescales varying from subannual to interannual. The corresponding statistical oscillation modes are obtained by spectral analysis. By analyzing the spatiotemporal structures of these modes, it is found that the subannual oscillation with a 9-month period originates from the barotropic Rossby basin mode, and the interarmual oscillations with periods ranging from 1.5 years to 4.6 years originate from the recirculation gyre modes, which include the barotropic and the baroclinic recirculation gyre modes. 相似文献
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B. Kochtubajda 《Atmospheric Research》1995,35(2-4)
Physical experiments designed to explore the potential of rain augmentation through airborne glaciogenic seeding on small, isolated non-precipitating cumuliform clouds near Red Deer, Alberta were carried out during the period 1982–1985. The microstructure of 90 cumulus congestus clouds have been documented through repeated in-situ sampling using a cloud physics instrumented aircraft platform. Observations from the inspection passes of 57 clouds seeded with either dry ice pellets or silver iodide pyrotechnics, and all the passes of 33 natural clouds are presented.Measurements of the cloud droplet concentration indicate that Alberta cumulus clouds are typically continental in nature, with an average droplet concentration of 535 cm−3 and an average droplet diameter of 10.6 μm. Alberta clouds have average liquid water contents of 0.57 g m−3, with a peak 1-sec value of 3.17 g m−3. The 1-km average liquid water contents are 0.83 g m−3, with a peak value of 2.81 g m−3. Cloud lifetimes vary between 11 and 20 minutes. Concentrations of naturally occurring ice crystals are found to be low. The average maximum 1-km ice concentration was 31−1, and the peak 1-km concentration was 73.11−1 in the natural cloud dataset. Evidence of precipitation-sized particles was detected in 21% (7 of 33) of the clouds, and precipitation below cloud base was detected in 6% (2 of 33) of the clouds.A comparison of the Alberta cloud characteristics to the cumulus clouds from different locations showed that there are some distinct differences between Alberta clouds and the clouds from the other regions. 相似文献
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利用气象业务中使用的L波段探空数据和毫米波云雷达观测资料,分析探空相对湿度在入云和出云时的变化规律,提出一种基于探空相对湿度阈值与梯度相结合的云区边界识别改进算法,并利用云雷达观测数据对算法识别结果进行验证.利用北京市南郊观象台2019年1—6月层状云样本验证分析,结果表明:改进算法相比相对湿度阈值法,对云区边界识别更... 相似文献
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利用常规观测资料和NCEP/NCAR(1°×1°)逐6 h再分析资料,对承德市2017年5月5—6日大风天气的环流形势和物理量进行分析,结果表明气旋的快速发展(气旋加深率0.84 B)导致锋生加强,引发气压和变压梯度加大是导致大风的直接原因。500 hPa高压脊东移迫使冷空气向南堆积,高空槽不断发展成为冷涡,温度平流为地面气旋的发展提供热力条件,高低层涡度平流的差异,也是地面气旋快速发展的重要原因;当1.5 PVU位涡面伸展至对流层低层时,局地位涡异常在气旋的发展过程中不可忽视;高空急流出口区发生质量调整,出口区左侧的辐散强度达10×10~(-5) s~(-1),使低层大气减压,有利于气旋发展。 相似文献
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利用常规观测资料和NCEP 1°×1°再分析资料,通过对发生在江苏的三次不同量级的区域性暴雪、大雪和中雪过程典型个例进行对比分析,发现降雪时,700hPa低空急流的位置和强度是影响降雪量级的主要因素之一;降雪区上空涡度的垂直分布遵循低层负涡度、中层正涡度和高层负涡度的配置,暴雪时正涡度强且正涡度区最为深厚,动力抬升作用强,中雪发生时正涡度区相对最为浅薄,不利于形成强辐合抬升,动力抬升作用弱。且暴雪和大雪发生时基本上整层都为垂直螺旋度正值区,中雪时没有出现明显的正值区;暴雪和大雪过程时中低层都具有明显的逆温层,中高层西南急流造成的对流层中层的爆发性增温是逆温层形成的关键,中雪发生时不一定有逆温层结;降雪强度与湿位涡分量绝对值存在一定的正相关关系。 相似文献
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Governance,complexity, and resilience 总被引：1，自引：0，他引：1
Andreas Duit Victor Galaz Katarina Eckerberg Jonas Ebbesson 《Global Environmental Change》2010,20(3):363-368
This special issue brings together prominent scholars to explore novel multilevel governance challenges posed by the behavior of dynamic and complex social-ecological systems. Here we expand and investigate the emerging notion of “resilience” as a perspective for understanding how societies can cope with, and develop from, disturbances and change. As the contributions to the special issue illustrate, resilience thinking in its current form contains substantial normative and conceptual difficulties for the analysis of social systems. However, a resilience approach to governance issues also shows a great deal of promise as it enables a more refined understanding of the dynamics of rapid, interlinked and multiscale change. This potential should not be underestimated as institutions and decision-makers try to deal with converging trends of global interconnectedness and increasing pressure on social-ecological systems. 相似文献
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D.T. Patterson J.K. Westbrook R.J.V. Joyce† P.D. Lingren J. Rogasik 《Climatic change》1999,43(4):711-727
The geographic distribution, vigor, virulence, and agricultural impact of weeds, insects, and plant pathogens will be affected by climatic changes accompanying the global "greenhouse effect." Weed/crop competitive interactions, particularly among species differing in photosynthetic pathway (C3 v C4), may be altered, with the C3 species favored by increasing CO2. Physiological and biochemical changes induced in host crop plants by rising CO2 may affect feeding patterns of pest insects. Compilation of climatic thresholds for phenological development of pest insects reveals the potential for shifts in pest behavior induced by global warming and other climatic change. Generation times may be reduced, enabling more rapid population increases to occur. Poleward migration may be accelerated during the crop season. The epidemiology of plant diseases also will be altered. Prediction of disease outbreaks will be more difficult in periods of rapidly changing climate and unstable weather. Environmental instability and increased incidence of extreme weather may reduce the effectiveness of pesticides on targeted pests or result in more injury to non-target organisms. Biological control may be affected either negatively or positively. Overall, the challenge to agriculture from pests probably will increase. 相似文献