气侯变化对东部季风区赣江和官厅流域径流的影响

选取中国东部季风区南方赣江流域和北方官厅流域,基于逐日气象和水文观测数据率定和验证了HBV水文模型,并以国际耦合模式比较计划第五阶段（CMIP5）中输出要素最多的5个全球气候模式在3种典型浓度路径（RCP2.6、RCP4.5和RCP8.5）下的预估结果驱动HBV模型,预估了气候变化对21世纪两个流域径流的影响。结果表明：(1) 1961—2017年,赣江和官厅流域年平均气温均呈显著上升趋势,升温速率分别为0.17℃/(10 a)和0.28℃/(10 a);同期,赣江流域降水显著增加,官厅流域降水微弱下降。不同RCP情景下,21世纪两个流域均将持续变暖、降水有所增加,北方官厅流域的气温和降水增幅均大于南方赣江流域。(2) 21世纪,官厅流域年、季径流增幅远大于赣江流域。官厅流域年径流在近期（2020—2039年）、中期（2050—2069年）、末期（2080—2099年）均呈增加趋势,RCP8.5情景下增幅最大、RCP4.5最小。赣江流域在RCP4.5下,近期、中期年径流相对基准期略有减少,但在整个21世纪径流呈上升趋势;RCP2.6和RCP8.5下,21世纪中期以后径流增幅下降。(3) 21世纪,东部季风区北部的官厅流域发生洪涝、南方赣江流域发生干旱的可能性增大,不同RCP情景预估得到相同的结论。     

CMIP5模式对21世纪全球和中国年平均地表气温变化和2℃升温阈值的预估

基于参加国际耦合模式比较计划第5阶段（CMIP5）的29个全球气候模式开展的历史气候模拟和3种典型浓度路径（RCP2.6、RCP4.5、 RCP8.5）下21世纪气候预估的结果,分析了单个模式和多模式集合平均（MME）的21世纪全球与中国年平均地表气温（ASAT）变化特征及2℃升温阈值的出现时间。多模式集合平均的结果显示：全球和中国年平均地表气温均将继续升高,21世纪末的升温幅度随着辐射强迫的增大而增大。RCP2.6情景下,年平均地表气温增幅先升高后降低,全球（中国）年平均地表气温在2056年（2049年）达到升温峰值,21世纪末升温1.74℃（2.12℃）;RCP4.5情景下,年平均地表气温在21世纪前半叶逐渐升高,之后升温趋势减缓,21世纪后期趋于平稳,21世纪末全球（中国）年平均地表气温增幅为2.60℃（3.39℃）;RCP8.5情景下,21世纪年平均地表气温快速升高,21世纪末全球（中国）年平均地表气温增幅为4.75℃（6.55℃）。全球平均的年平均地表气温增幅,在RCP2.6情景下没有超过2℃,RCP4.5和RCP8.5情景下分别在2047和2038年达到2℃。RCP2.6、RCP4.5和RCP8.5情景下中国年平均地表气温增幅连续5 a不低于2℃的时间分别在2032、2033和2027年,明显早于全球平均。任一典型浓度路径情景下,达到2℃升温的时间,北半球同纬度地区早于南半球,同半球高纬度地区早于低纬度地区,同纬度地区陆地早于海洋。3种不同典型浓度路径情景下21世纪全球和中国年平均地表气温将继续升高这一结果是可信的,RCP4.5和RCP8.5情景下全球和中国年平均地表气温增幅超过2℃的结果模式之间有较高的一致性。多模式预估的全球和中国年平均地表气温升幅和不同幅度升温的出现时间均存在一定的不确定性,预估结果的不确定性随预估时间的延长而增大;相同情景下,中国年平均地表气温预估的不确定性大于全球。     

东北地区气候变化CMIP5模式预估

利用CMIP5的多模式集合资料,从时间变化和空间分布两方面分析了不同情景下(RCP2.6、RCP4.5、RCP8.5)中国东北地区未来100年的气候变化。结果显示:3种排放情景下,21世纪东北地区气温和降水呈显著增长趋势,中期和末期增幅较明显,冬季增幅高于其他季节,RCP8.5情景下气温增暖最为显著,RCP4.5次之,RCP2.6最小,随着年代的推移,气温和降水年较差逐渐减小;空间分布显示:3种排放情景下各个时期的增温分布形式基本一致,由南向北逐渐增大,辽宁南部增温幅度最小,最显著地区位于黑龙江大兴安岭;不同情景下气温变化率的分布形势略有不同,但均呈显著增温趋势;3种排放情景下降水距平百分率均为增加趋势,呈由东向西逐渐增大的经向分布特征;不同情景下的降水变化率分布形势相似,呈南大北小特征,辽宁地区增长最为明显,黑龙江西部地区增长相对较小。     

未来东北地区农业气候资源的时空演变特征

研究采用NorESM1-M模式输出的气候情景资料驱动农业生态区模型,分析了21世纪中期在RCP 2.6和RCP8.5典型浓度路径下的东北区域气候资源变化。研究表明:在RCP2.6、RCP8.5两种气候变化情景下,东北区域年平均气温呈现升高趋势,≥10℃积温所反映的热量条件得到显著改善,以黑龙江省和辽中南积温的增加最为明显;受气温升高影响,2050s参考作物蒸散普遍增加。区域内降水总量略有增加,东北西部干旱地区状况略有改善,东部地区更加湿润;趋于暖湿的气候促使作物生长季延长,到21世纪中期,全区最长增加12.4天。     

21世纪青藏高原可能的气候变化

利用1980～1999年CRU温度和降水资料,结合柯本气候分类,模拟了20世纪末期青藏高原气候分布,模拟结果与FAO结果吻合较好.基于A1B情景下的高分辨率动力降尺度资料,分析了21世纪中期、末期青藏高原温度和降水变化趋势.在此基础上,模拟了21世纪青藏高原可能的气候带分布,分析其可能变化趋势.分析结果显示,21世纪青藏高原的气候类型向着更暖湿的方向发展,月平均温度和月累积降水量都有增加的趋势,并且在21世纪中期达到了最大值.     

未来气候变化情景下长江上游年径流量变化趋势研究

依据政府间气候变化委员会(IPCC)第五次评估报告(AR5)未来不同排放情景(RCPs)下的多模式(CMIP5)气温和降水预估结果,构建基于气温和降水的未来径流量预估模型,并以宜昌站为例分析了不同模式不同排放情景下未来80年(2020～2099年)长江上游年径流量的变化趋势。多模式集合平均预估结果表明:在99%的置信水平下,未来80年长江上游年径流量在RCP2.6排放情景下呈不显著增加趋势,在RCP4.5排放情景下呈不显著减小趋势,而在RCP8.5排放情景下则呈显著减小趋势;在RCP2.6、RCP4.5和RCP8.5排放情景下未来80年长江上游年径流量预估均值相对于1961～2000年分别减少6.42%、10.99%和13.25%;同时,未来80年长江上游年径流量变化具有一定的年代际特征,在RCP2.6和RCP4.5排放情景下21世纪初期偏多、中期偏少而后期变化并不明显,在RCP8.5排放情景下则是21世纪中期以前偏多而中期以后明显偏少。本研究方法可为未来气候变化情景预估分析提供技术参考,本研究成果可供气候变化背景下长江上游乃至长江流域水资源开发利用及对策分析提供决策依据。      

“一带一路”区域未来气候变化预估

利用耦合模式比较计划第5阶段(CMIP5)提供的18个全球气候模式的模拟结果,预估了3种典型浓度路径(RCP2.6、RCP4.5、RCP8.5)下“一带一路”地区平均气候和极端气候的未来变化趋势。结果表明:在温室气体持续排放情景下,“一带一路”地区年平均气温在未来将会持续上升,升温幅度随温室气体浓度的增加而加大。在高温室气体排放情景(RCP8.5)下,到21世纪末期,平均气温将普遍升高5℃以上,其中北亚地区升幅最大,南亚和东南亚地区升幅最小。对于降水的变化,预估该区域大部分地区的年降水量将增加,其中西亚和北亚增加最为明显,而且在21世纪中期,RCP2.6情景下的增幅要比RCP4.5和RCP8.5情景下的偏大,而在21世纪后期,RCP8.5情景下降水的增幅比RCP2.6和RCP4.5情景下的偏大。未来极端温度也将呈升高的趋势,增温幅度高纬度地区大于低纬度地区、高排放情景大于低排放情景。而且在高纬度区域,极端低温的增暖幅度要大于极端高温的增幅。连续干旱日数在北亚和东亚总体呈现减少趋势,而在其他地区则呈增加趋势。极端强降水在“一带一路”区域总体上将增强,增强最明显的地区位于南亚、东南亚和东亚。     

RCPs情景下贵州省气候变化预估分析

使用国际耦合模式比较计划第五阶段CMIP5的模式结果,在不同RCP情景下对贵州省未来气温、降水进行了预估。通过对气温、降水的模拟值和实测值的标准化均方根误差的评估得知,模式对贵州省气温的模拟能力较强,对降水的模拟能力相对较差。预估结果表明:未来在RCP8.5、RCP4.5和RCP2.6情景下贵州省气温均是明显的上升趋势,降水小幅度增加,增温(增湿)速率分别为0.5℃/10a(1.0%/10a)、0.2℃/10a(0.9%/10a)和0.1℃/10a(0.6%/10a),到了21世纪末期相对于基准期气温(降水)分别增加4.5℃(5.2%)、2.3℃(5.4%)和1.3℃(4.2%)。空间分布总体上增温幅度从西南向东北逐渐变大,而降水相对于基准期变化的区域性差异较大。总体来说,21世纪温室气体浓度越高,增温增湿速率越快。     

未来气候情景下中国东部极端降水和气温的危险性特征

基于BCC-CSM11模式降尺度预估结果,通过构建极端天气气候事件的危险性指数,考察和分析了中国东部极端降水和气温未来气候情景下可能的变化趋势和危险性分布格局。结果表明: 1）在中等排放情景（RCP4.5）下,近期（2021—2050年）极端降水和极端高温危险性呈现增强趋势,危险性指数增幅分别约为2%和10%,而极端低温危险性则呈减弱趋势,危险性指数降幅约为4%。21世纪末期（2070—2099年）,极端降水和气温危险性均基本保持现有水平,未有明显趋势。在高等排放情景（RCP8.5）下,极端降水和极端高温危险性将持续增强,至21世纪末危险性指数增幅分别约为5%和60%;极端低温危险性持续减弱,危险性指数降幅约为5%。2）在未来气候情景下,中国东部极端高温的危险性以全域持续增强为主要特征,特别是西南地区、长江以南地区和东南沿海危险性增强最为显著。至21世纪末,在高排放情景下的危险性指数增幅为30%—60%。极端降水危险性在黄河上游、长江上游和下游以及东北地区中南部等地区呈增强趋势,危险性指数增幅为3%—5%。极端低温危险性全域呈减弱趋势,至21世纪末期高等排放情景下的危险性指数最高降幅为7%—9%。     

8个CMIP5模式对中国极端气温的模拟和预估

利用8个耦合模式比较计划第五阶段（CMIP5）模式结果,采用加权平均方法进行多模式集合,并与NCEP再分析资料进行对比分析,评估了CMIP5模式对中国极端气温的模拟效果,在此基础上,对未来极端气温进行预估。CMIP5模式对中国8个极端气温指数和20年一遇最高（低）气温有模拟能力,所有极端气温指数模拟和观测结果的时间相关均达到0.10显著性水平,20年一遇最高、最低气温模拟和观测结果空间相关系数均超过0.98。在中等排放RCP4.5情景下,未来中国极暖（冷）日数增多（减少）,到21世纪中期热浪指数增加2.6倍,到21世纪末期寒潮指数减少71%,20年一遇最高（低）气温在中国地区均呈现升高趋势,局部升温幅度达到4℃。     

PREDICTION AND UNCERTAINTY OF CLIMATE CHANGE IN CHINA DURING 21ST CENTURY UNDER RCPS

Based on integrated simulations of 26 global climate models provided by the Coupled Model Intercomparison Project(CMIP), this study predicts changes in temperature and precipitation across China in the 21 st century under different representative concentration pathways(RCPs), and analyzes uncertainties of the predictions using Taylor diagrams. Results show that increases of average annual temperature in China using three RCPs(RCP2.6, RCP4.5,RCP8.5) are 1.87 ℃, 2.88 ℃ and 5.51 ℃, respectively. Increases in average annual precipitation are 0.124, 0.214, and 0.323 mm/day, respectively. The increased temperature and precipitation in the 21 st century are mainly contributed by the Tibetan Plateau and Northeast China. Uncertainty analysis shows that most CMIP5 models could predict temperature well, but had a relatively large deviation in predicting precipitation in China in the 21 st century. Deviation analysis shows that more than 80% of the area of China had stronger signals than noise for temperature prediction;however, the area proportion that had meaningful signals for precipitation prediction was less than 20%. Thus, the multi-model ensemble was more reliable in predicting temperature than precipitation because of large uncertainties of precipitation.     

Steric sea level change in twentieth century historical climate simulation and IPCC-RCP8.5 scenario projection: A comparison of two versions of FGOALS model

To reveal the steric sea level change in 20th century historical climate simulations and future climate change projections under the IPCC’s Representative Concentration Pathway 8.5 (RCP8.5) scenario, the results of two versions of LASG/IAP’s Flexible Global Ocean-Atmosphere-Land System model (FGOALS) are analyzed. Both models reasonably reproduce the mean dynamic sea level features, with a spatial pattern correlation coefficient of 0.97 with the observation. Characteristics of steric sea level changes in the 20th century historical climate simulations and RCP8.5 scenario projections are investigated. The results show that, in the 20th century, negative trends covered most parts of the global ocean. Under the RCP8.5 scenario, global-averaged steric sea level exhibits a pronounced rising trend throughout the 21st century and the general rising trend appears in most parts of the global ocean. The magnitude of the changes in the 21st century is much larger than that in the 20th century. By the year 2100, the global-averaged steric sea level anomaly is 18 cm and 10 cm relative to the year 1850 in the second spectral version of FGOALS (FGOALS-s2) and the second grid-point version of FGOALS (FGOALS-g2), respectively. The separate contribution of the thermosteric and halosteric components from various ocean layers is further evaluated. In the 20th century, the steric sea level changes in FGOALS-s2 (FGOALS-g2) are largely attributed to the thermosteric (halosteric) component relative to the pre-industrial control run. In contrast, in the 21st century, the thermosteric component, mainly from the upper 1000 m, dominates the steric sea level change in both models under the RCP8.5 scenario. In addition, the steric sea level change in the marginal sea of China is attributed to the thermosteric component.     

Climate change in the 21st century simulated by HadGEM2-AO under representative concentration pathways

We present climate responses of Representative Concentration Pathways (RCPs) using the coupled climate model HadGEM2-AO for the Coupled Model Intercomparison Project phase 5 (CMIP5). The RCPs are selected as standard scenarios for the IPCC Fifth Assessment Report and these scenarios include time paths for emissions and concentrations of greenhouse gas and aerosols and land-use/land cover. The global average warming and precipitation increases for the last 20 years of the 21st century relative to the period 1986-2005 are +1.1°C/+2.1% for RCP2.6, +2.4°C/+4.0% for RCP4.5, +2.5°C/+3.3% for RCP6.0 and +4.1°C/+4.6% for RCP8.5, respectively. The climate response on RCP 2.6 scenario meets the UN Copenhagen Accord to limit global warming within two degrees at the end of 21st century, the mitigation effect is about 3°C between RCP2.6 and RCP8.5. The projected precipitation changes over the 21st century are expected to increase in tropical regions and at high latitudes, and decrease in subtropical regions associated with projected poleward expansions of the Hadley cell. Total soil moisture change is projected to decrease in northern hemisphere high latitudes and increase in central Africa and Asia whereas near-surface soil moisture tends to decrease in most areas according to the warming and evaporation increase. The trend and magnitude of future climate extremes are also projected to increase in proportion to radiative forcing of RCPs. For RCP 8.5, at the end of the summer season the Arctic is projected to be free of sea ice.     

CMIP5 simulated change in the intensity of the Hadley and Walker circulations from the perspective of velocity potential

Based on the simulations of 31 global models in CMIP5, the performance of the models in simulating the Hadley and Walker circulations is evaluated. In addition, their change in intensity by the end of the 21 st century(2080–2099) under the RCP4.5 and RCP8.5 scenarios, relative to 1986–2005, is analyzed from the perspective of 200 h Pa velocity potential.Validation shows good performance of the individual CMIP5 models and the multi-model ensemble mean(MME) in reproducing the meridional(zonal) structure and magnitude of Hadley(Walker) circulation. The MME can also capture the observed strengthening tendency of the winter Hadley circulation and weakening tendency of the Walker circulation. Such secular trends can be simulated by 39% and 74% of the models, respectively. The MME projection indicates that the winter Hadley circulation and the Walker circulation will weaken under both scenarios by the end of the 21 st century. The weakening amplitude is larger under RCP8.5 than RCP4.5, due to stronger external forcing. The majority of the CMIP5 models show the same projection as the MME. However, for the summer Hadley circulation, the MME shows little change under RCP4.5 and large intermodel spread is apparent. Around half of the models project an increase, and the other half project a decrease. Under the RCP8.5 scenario, the MME and 65% of the models project a weakening of the summer southern Hadley circulation.     

RegCM4对华北区域21世纪气候变化预估研究

利用国家气候中心完成的RegCM4区域气候模式在RCP4.5和RCP8.5两种排放路径下的气候变化动力降尺度试验结果,在检验模式对基准期(1986—2005年)气温和降水模拟能力基础上,进行华北区域21世纪气候变化预估分析。结果表明：RegCM4对华北区域基准期气温和降水的模拟能力较好。未来21世纪,两种情景下华北区域气温、降水、持续干期(consecutive dry days, CDD)和强降水量(R95p)变化逐渐增大,但变化幅度在高排放的RCP8.5情景下更为显著,其中近期(2021—2035年)、中期(2046—2065年)、远期(2080—2098年)RCP8.5情景下年平均气温分别升高1.77、3.44、5.82℃,年平均降水分别增加8.1%、14%、19.3%,CDD分别减少3、3、12 d, R95p分别增加30.8%、41.9%、69.8%。空间上,未来21世纪华北区域内年、冬季、夏季平均气温将一致升高,夏季升温幅度最大;年、冬季、夏季平均降水整体以增加为主,冬季降水增加幅度最大;CDD以减少为主,但近期和中期在山西和京津冀有所增加,而R95p以增加为主,表明21世...     

CMIP5模式对中国地区气温模拟能力评估与预估

利用第五次国际耦合模式比较计划（CMIP5）中29个气候模式的气温模拟结果,评估了各模式对中国地区年平均气温的模拟能力,对未来不同典型浓度路径（RCPs）下中国地区气温的可能变化给出了预估。结果表明：各模式能较好地模拟过去100多年中国地区增温趋势和年平均气温的空间分布,从模式间标准差来看,各模式对中国中部、南部气温模拟具有较高的一致性。利用相对均方根误差分析了各模式的模拟能力,对于多时间尺度（月、年）气温的气候平均态,有7个模式表现良好,高于中等水平,5个模式的模拟能力低于中等水平,模式集合平均值的模拟效果优于大多数单个模式。根据29个模式的评估结果,使用模拟性能相对较好的模式分析了未来不同排放情景下中国地区气温变化,21世纪前期,不同排放情景之间的预估结果差别较小,21世纪中期各情景之间的差别逐渐增大,到21世纪后期,3种排放情景的升温差别明显增大。     

基于CMIP5模式的中国地区未来洪涝灾害风险变化预估

利用22个CMIP5全球气候模式模拟结果,结合社会经济以及地形高度数据,分析了RCP8.5温室气体排放情景下21世纪近期（2016-2035年）、中期（2046-2065年）和后期（2080-2099年）中国洪涝致灾危险性、承灾体易损性以及洪涝灾害风险。结果表明,洪涝灾害危险等级较高的地区集中在中国的东南部,洪涝承灾体易损度高值区位于中国的东部地区。在RCP8.5情景下,未来我国洪涝灾害高风险区主要出现在四川东部、华东的大部分地区、华北的京津冀地区、陕西和山西的部分地区以及东南沿海部分地区。东北地区的各大省会城市面临洪涝灾害的风险也很高。与基准期（1986-2005年）相比,21世纪后期,虽然发生洪涝灾害的区域变化不大,但高风险区域有所增加。鉴于模式较粗的分辨率以及确定权重系数的方法学等问题,洪涝灾害风险的预估还存在较大的不确定性。     

Assessment of CMIP5 global model simulations and climate change projections for the 21 st century using a modified Thornthwaite climate classification

A modified Thornthwaite Climate Classification is applied to a 32-member ensemble of CMIP5 GCMs in order to 1) evaluate model performance in the historical climate and 2) assess projected climate change at the end of the 21 ^{s t} century following two greenhouse gas representative concentration pathways (RCP4.5 and RCP8.5). This classification scheme differs from the well-known Köppen approach as it uses potential evapotranspiration for thermal conditions, a moisture index for moisture conditions, and has even intervals between climate classes. The multi-model ensemble (MME) reproduces the main spatial features of the global climate reasonably well, however, in many regions the climate types are too moist. Extreme climate types, such as those found in polar and desert regions, as well as the cool- and cold-wet types of eastern North America and the warm and cool-moist types found in the southern U.S., eastern South America, central Africa and Europe are reproduced best by the MME. In contrast, the cold-dry and cold-semiarid climate types characterizing much of the high northern latitudes and the warm-wet type found in parts of Indonesia and southeast Asia are poorly represented by the MME. Regionally, most models exhibit the same sign in moisture and thermal biases, varying only in magnitude. Substantial changes in climate types are projected in both the RCP4.5 and RCP8.5 scenarios. Area coverage of torrid climate types expands by 11 % and 19 % in the RCP4.5 and RCP8.5 projections, respectively. Furthermore, a large portion of these areas in the tropics will experience thermal conditions which exceed the range of historical values and fall into a novel super torrid climate class. The greatest growth in moisture types in climate zones is among those with dry climates (moisture index values < 0) with increased areas of more than 8 % projected by the RCP8.5 MME.