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40 a来,长江流域大部分地区年平均温度呈现上升趋势,20世纪90年代增温幅度最大; 在季节变化上,除了夏季,其他季节都呈升高趋势;全流域夏季降水量显著增加,尤其表现在20世纪90年代,这主要由于长江流域大部分地区夏季暴雨日数显著增加的结果;夏季径流量和年最大洪峰流量在长江中下游地区均呈现显著增加趋势。长江流域夏季降水量的增加,尤其是暴雨日数的增多必然会增加长江流域中下游地区的洪水风险。20世纪90年代以来,长江洪水的频繁发生是对气候变暖的响应。 相似文献
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气候变化的归因与预估模拟研究 总被引：14，自引：2，他引：12
本文总结了近五年来中国科学院大气物理研究所在气候变暖的归因模拟与预估研究上的主要进展。研究表明,利用海温、太阳辐射和温室气体等实际强迫因子驱动大气环流模式,能够较为合理地模拟全球平均地表气温在20世纪的演变,但是难以模拟出包括北大西洋涛动／北极涛动和南极涛动在内的高纬度环流的长期变化趋势。利用温室气体和硫酸盐气溶胶等“历史资料”驱动气候系统模式,能够较好地模拟出20世纪后期的全球增暖,但如果要再现20世纪前期(1940年代)的变暖,还需同时考虑太阳辐射等自然外强迫因子。20世纪中国气温演变的耦合模式模拟技巧,较之全球平均情况要低;中国气候在1920年代的变暖机理目前尚不清楚。对于近50年中国东部地区“南冷北暖”、“南涝北旱”的气候变化,基于大气环流模式特别是区域气候模式的数值试验表明,夏季硫酸盐气溶胶的负辐射效应超过了温室气体的增暖效应,从而对变冷产生贡献。但现有的数值模拟证据,不足以说明气溶胶增加对“南涝北旱”型降水异常有贡献。20世纪中期以来,青藏高原主体存在明显增温趋势,温室气体浓度的增加对这种增暖有显著贡献。多模式集合预估的未来气候变化表明,21世纪全球平均温度将继续增暖,增温幅度因不同排放情景而异;中国大陆年均表面气温的增暖与全球同步,但增幅在东北、西部和华中地区较大,冬季升温幅度高于夏季、日最低温度升幅要强于日最高温度;全球增暖有可能对我国中东部植被的地理分布产生影响。伴随温室气体增加所导致的夏季平均温度升高,极端温度事件增多;在更暖的气候背景下,中国大部分地区总降水将增多,极端降水强度加大且更频繁发生,极端降水占总降水的比例也将增大。全球增暖有可能令大洋热盐环流减弱,但是减弱的幅度因模式而异。全球增暖可能不是导致北太平洋副热带－热带经圈环流自20世纪70年代以来变弱的原因。文章同时指出了模式预估结果中存在的不确定性。 相似文献
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长江源区近44年气候变化的若干统计分析 总被引：11，自引：1，他引：10
利用长江源区5个气象站44年的气温、降水量资料以及其中2个探空站500hPa露点资料,分析了该地区气候变化趋势、突变等情况。结果表明：近44年来长江源区气温普遍升高,冬季升温幅度较大,夏季增温趋势明显,进入21世纪后,长江源区春季平均气温在降低,夏、秋季平均气温增高较趋缓,而冬季增温加剧的趋势十分明显;年、夏季降水量变化呈微弱减少趋势,而冬、春和秋季降水量呈现出增加趋势,其中春季增幅较大,冬季增湿趋势明显;长江源区年平均气温在20世纪60年代末70年代初就显现出波动回升的趋势,在1986年前后发生了由冷到暖的突变,冬、春季降水量均在20世纪70年代和80年代出现了由少向多的突变。长江源区气候在波动性变暖变干过程中,自1986年起出现了气候转向暖湿的信号,其主要原因在于全球变暖并由此引起的海洋蒸发和陆地蒸散加强,地气水分循环加快,空中水汽输送加强。 相似文献
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利用中国科学院大气物理研究所LASG研发的全球海洋-大气-陆面系统模式(GOALS 4.0),引入了大气中真实的温室气体浓度变化,对华北地区的气候变化进行了模拟研究。为了检验GOALS 4.0模式对于未来30年华北地区气候变化趋势模拟结果的可信度,分析评估了GOALS 4.0模式对当代气候变化的模拟能力。模拟结果基本再现了20世纪60—70年代末的全球和北半球温度偏低以及80年代开始的增温现象,也较好地模拟了华北地区近50年来的两个重要气候冷(1950—1976年)、暖(1977—2000年)时期,模拟结果与实际观测相关为0.34(达到了0.05信度),华北地区的冬季温度变化幅度介于中国大陆东、西部之间。模式对华北地区夏季降水在20世纪80年代前后经历的丰枯时期转变模拟也比较理想。在此基础上,根据IPCC提供的大气温室气体未来排放情景,进一步模拟预估了华北地区未来30年的气候变化趋势。结果发现,在未来的30年中,中国大陆冬季温度将会呈现出不断上升趋势,华北是中国大陆增温最显著、增温幅度最大的地区,到2030年华北地区冬季的增温幅度相对多年平均(1961—1990年)上升2.5℃左右。未来30年的夏季,由于华北地区处于明显的水汽辐合区,偏南气流较强,大气中的可降水量增加,使得中国大陆的降水格局也会发生相应变化,呈现出南少北多的分布型态,华北地区夏季降水会明显增多,南方地区降水则有所减少。 相似文献
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利用系统聚类分析和相关分析方法,根据1953—2005年内蒙古东部产粮区48个气象站的气象资料,进行了气候相似区划分;并得出各区在热量、水分的时间变化上具有较高的区域一致性。据此,以区域内各站点的温度、降水和日照时数的平均值作为区域热水光时间序列,分析了各气候要素变化特征及其对农业可能产生的影响。结果表明:各区域温度呈上升趋势,增温速率(平均增温为0.3—0.4℃/10 a)高于中国平均增温速率(0.22℃/10 a),增温幅度呈从西向东递增的趋势,平均最低气温增幅最大,平均最高气温增温幅度与海拔呈正相关,尤以1988年以后变暖趋势最为明显;降水量基本呈减少趋势,年代际波动较大;20世纪90年代至今,内蒙古东部产粮区生长季降水明显减少,气温迅速升高,暖干化趋势表现明显,温差减小和日照时数减少,水热匹配格局发生改变,粮食产量出现减少趋势的可能性较大。 相似文献
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利用系统聚类分析和相关分析方法,根据1953--2005年内蒙古东部产粮区48个气象站的气象资料．进行了气候相似区划分;并得出各区在热量、水分的时间变化上具有较高的区域一致性。据此,以区域内各站点的温度、降水和日照时数的平均值作为区域热水光时间序列,分析了各气候要素变化特征及其对农业可能产生的影响。结果表明：各区域温度呈上升趋势,增温速率（平均增温为0．3-0．4℃／10a）高于中国平均增温速率（0．22℃／10a）,增温幅度呈从西向东递增的趋势,平均最低气温增幅最大,平均最高气温增温幅度与海拔呈正相关,尤以1988年以后变暖趋势最为明显;降水量基本呈减少趋势,年代际波动较大;20世纪90年代至今,内蒙古东部产粮区生长季降水明显减少,气温迅速升高,暖千化趋势表现明显,温差减小和日照时数减少,水热匹配格局发生改变,粮食产量出现减少趋势的可能性较大。 相似文献
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天津滨海区50年局地气候变化特征 总被引：18，自引：1，他引：18
利用1951～2000年天津滨海新区的气象资料，分析了50年来气温、降水、日照的变化特征，结果显示天津滨海新区年、冬季、夏季气温均呈上升趋势，20世纪50～80年代冬季增温强于夏季，90年代则夏季升温最为明显；降水总体趋势下降，90年代降到50年来的最小值；年平均日照时数也呈总体下降趋势，90年代下降最为显著。表明天津滨海新区气候正在趋向变暖，特别是近10年来气温急剧升高，降水量锐减、日照时数明显减少，使得高温、干旱、少日照成为天津滨海新区气候的突出问题。 相似文献
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东北和华北东部气温异常特征及其成因的初步分析 总被引：11，自引：14，他引：11
采用REOF，SVD分析方法，首先指出东北和华北东部气温异常是全国气温异常的第一主分量，进而分析其异常特征及成因。结果表明：全区年、季气温均呈上升趋势，其中冬季增温最大，极端低温较极端高温升高明显。近百年来，全区增温幅度明显高于20世纪全球平均增暖水平。冬季，对流层中、低层上，当纬向西风偏强时，东北和华北东部易高温；而当经向风强盛时，易低温。夏季，气温异常与东北冷涡活动有关；1980年代以来气温显著变暖与对流层中、低层气压场的年代际突变有关。冬夏季气温与东亚冬夏季风、Nino3区海温的关系并不显著，但在1990年代以前，东北夏季低温与El Nino的对应关系较好。 相似文献
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江西贵溪市近50年气候特征分析 总被引：2，自引：2，他引：2
利用1953—2002年贵溪市国家一级站的气象资料,分析了近50 a贵溪市气温、降水、日照的变化特征。分析结果表明,贵溪市年、冬季气温呈上升趋势,而夏季气温呈下降趋势,20世纪90年代冬季增温最为明显;年降水总体呈略上升趋势,90年代降水量异常偏多;年日照时数总体呈下降趋势。分析结果还表明,贵溪市气候正在趋向变暖,特别是近10 a来气温升高明显。 相似文献
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利用全国175个测站1960—1999年间的日平均气温资料,分别选取1960—1989年(气候态A)、1970—1999年(气候态B)作为气候背景,采用蒙特卡洛显著性检验法检验了这两个气候态背景下我国冬夏两季季节平均气温的差异显著性。并在此基础上利用气候百分位法分别分析了在这两个气候态背景下2000—2010年间我国冬夏两季的极端气温特征。分析结果表明,相对于夏季,冬季气候态A、B背景下季节平均气温的差异更为显著。冬夏两季,我国大部分地区极端低温事件的发生频率相对较低,而极端高温事件的发生频率相对较高。由于气候态B包含了全球变暖特征最为显著的20a,故在气候态B背景下,冬夏两季极端低(高)温事件的发生频率要高(低)于气候态A,这与全球变暖的趋势相吻合。 相似文献
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Factors favorable to frequent extreme precipitation in the upper Yangtze River Valley 总被引：1，自引：0，他引：1
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
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We isolate the contribution of warming, other large-scale changes and soil moisture decline and feedbacks in driving future projected changes in daily precipitation across Europe. Our confidence in each of these mechanisms differs, so this analysis then allows us to determine an overall confidence (or reliability) in the projected changes. In winter, increases in extreme precipitation over Europe as a whole are judged to be reliable, dominated by increased atmospheric moisture with warming. At scales less than about 2,000 km changing circulation patterns could enhance or offset this increase. Additionally, over the Scandinavian mountains warming-induced circulation changes do offset the effect of increased moisture and the overall change is unreliable. In summer, increases in extreme precipitation over northern Scandinavia and decreases over the Mediterranean are reliable in the absence of considerable circulation change. Over central Europe, an increase in the proportion of summer rainfall falling as extreme events is reliable. 相似文献
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利用喜马拉雅山脉中段南、北两侧6个气象站1971-2007年逐月气温、降水资料,分析了该地区气候变化趋势、异常及突变特征。结果表明：喜马拉雅山脉中段南、北两侧年、季平均气温均呈明显上升趋势,冬半年升温幅度大于夏半年。年及夏半年平均气温均为随年代升高趋势,而冬半年气温在20世纪80年代较70年代略偏低,90年代后又逐渐升高。21世纪前7 a升温最为显著,较20世纪70年代升高0.6～1.1℃。1997年该地区南侧年平均气温发生突变,突变后增温趋势更加明显。20世纪90年代末以来,异常偏暖年份出现的几率明显增加,且南侧多于北侧。喜马拉雅山脉中段北侧年及冬夏半年降水均呈增多趋势。南侧年和夏半年降水呈减少趋势,冬半年为增多趋势。降水异常出现在20世纪80、90年代,21世纪后降水出现异常的概率明显减少。近40 a,北侧气候具有暖湿化趋势;南侧冬半年与之类似,但夏半年及全年呈暖干化趋势。 相似文献
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AN ANALYSIS OF THE WINTER EXTREME PRECIPITATION EVENTS ON THE BACKGROUND OF CLIMATE WARMING IN SOUTHERN CHINA 总被引：2，自引：1，他引：1
Based on daily precipitation and monthly temperature data in southern China, the winter
extreme precipitation changes in southern China have been investigated by using the Mann-Kendall test
and the return values of Generalized Pareto Distribution. The results show that a winter climate
catastrophe in southern China occurred around 1991, and the intensity of winter extreme precipitation was
strengthened after climate warming. The anomalous circulation characteristics before and after the climate
warming was further analyzed by using the U.S. National Centers for Environmental Prediction/National
Center for Atmospheric Research reanalysis data. It is found that the tropical winter monsoon over East
Asia is negatively correlated with the precipitation in southeastern China. After climate warming the
meridionality of the circulations in middle and high latitudes increases, which is favorable for the
southward movement of the cold air from the north. In addition, the increase of the temperature over
southern China may lead to the decrease of the differential heating between the continent and the ocean.
Consequently, the tropical winter monsoon over East Asia is weakened, which is favorable for the transport
of the warm and humid air to southeastern China and the formation of the anomalous convergence of the
moisture flux, resulting in large precipitation over southeastern China. As a result, the interaction between
the anomalous circulations in the middle and high latitudes and lower latitudes after the climate warming
plays a major role in the increase of the winter precipitation intensity over southeastern China. 相似文献
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We present an analysis of climate change over Europe as simulated by a regional climate model (RCM) nested within time-slice atmospheric general circulation model (AGCM) experiments. Changes in mean and interannual variability are discussed for the 30-year period of 2071–2100 with respect to the present day period of 1961–1990 under forcing from the A2 and B2 IPCC emission scenarios. In both scenarios, the European region undergoes substantial warming in all seasons, in the range of 1–5.5°C, with the warming being 1–2°C lower in the B2 than in the A2 scenario. The spatial patterns of warming are similar in the two scenarios, with a maximum over eastern Europe in winter and over western and southern Europe in summer. The precipitation changes in the two scenarios also show similar spatial patterns. In winter, precipitation increases over most of Europe (except for the southern Mediterranean regions) due to increased storm activity and higher atmospheric water vapor loadings. In summer, a decrease in precipitation is found over most of western and southern Europe in response to a blocking-like anticyclonic circulation over the northeastern Atlantic which deflects summer storms northward. The precipitation changes in the intermediate seasons (spring and fall) are less pronounced than in winter and summer. Overall, the intensity of daily precipitation events predominantly increases, often also in regions where the mean precipitation decreases. Conversely the number of wet days decreases (leading to longer dry periods) except in the winter over western and central Europe. Cloudiness, snow cover and soil water content show predominant decreases, in many cases also in regions where precipitation increases. Interannual variability of both temperature and precipitation increases substantially in the summer and shows only small changes in the other seasons. A number of statistically significant regional trends are found throughout the scenario simulations, especially for temperature and for the A2 scenario. The results from the forcing AGCM simulations and the nested RCM simulations are generally consistent with each other at the broad scale. However, significant differences in the simulated surface climate changes are found between the two models in the summer, when local physics processes are more important. In addition, substantial fine scale detail in the RCM-produced change signal is found in response to local topographical and coastline features. 相似文献
17.
Europe and in particular its southern part are expected to undergo serious climate changes during summer in response to anthropogenic forcing, with large surface warming and decrease in precipitation. Yet, serious uncertainties remain, especially over central and western Europe. Several mechanisms have been suggested to be important in that context but their relative importance and possible interplays are still not well understood. In this paper, the role of soil-atmosphere interactions, cloud-temperature interactions and land–sea warming contrast in summer European climate change and how they interact are analyzed. Models for which evapotranspiration is strongly limited by soil moisture in the present climate are found to tend to simulate larger future decrease in evapotranspiration. Models characterized by stronger present-day anti-correlation between cloud cover and temperature over land tend to simulate larger future decrease in cloud cover. Large model-to-model differences regarding land–sea warming contrast and its impacts are also found. Warming over land is expected to be larger than warming over sea, leading to a decrease in continental relative humidity and precipitation because of the discrepancy between the change in atmospheric moisture capacity over land and the change in specific humidity. Yet, it is not true for all the models over our domain of interest. Models in which evapotranspiration is not limited by soil moisture and with a weak present-day anti-correlation between cloud cover and temperature tend to simulate smaller land surface warming. In these models, change in specific humidity over land is therefore able to match the continental increase in moisture capacity, which leads to virtually no change in continental relative humidity and smaller precipitation change. Because of the physical links that exist between the response to anthropogenic forcing of important impact-related climate variables and the way some mechanisms are simulated in the context of present-day variability, this study suggests some potentially useful metrics to reduce summer European climate change uncertainties. 相似文献
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Water Resources of the South Asian Region in a Warmer Atmosphere 总被引：1，自引：0，他引：1
The global mean surface temperature may rise by about 0.3oC per decade during the next Few decades as a result of anthropogenic greenhouse gas emissions in the earth’s atmosphere. The data generated in the greenhouse warming simulations (Business-as-Usual scenario of IPCC) with the climate models developed at Max Planck Institute for Meteorology, Hamburg have been used to assess future plausible hydrological scenario for the South Asian region. The model results indicate enhanced surface warming (2.7oC for summer and 3.6oC for winter) over the land regions of South Asia during the next hundred years. While there is no significant change in the precipitation over most of the land regions during winter, substantial increase in precipitation is likely to occur during summer. As a result, an increase in soil moisture is likely over central India, Bangladesh and South China during summer but a statistically sig-nificant decline in soil moisture is expected over central China in winter. A moderate decrease in surface runoff may occur over large areas of central China during winter while the flood prone areas of NE-India. Bangladesh and South China are likely to have an increase in surface runoff during summer by the end of next century. 相似文献