全球气候模式BCC-CSM2-MR(Beijing Climate Center-Climate System Model version 2-Medium Resolution)由国家(北京)气候中心自主研发并参与了第六阶段国际耦合模式比较计划,该模式在BCC-CSM1.1m版本基础上对大气辐射传输、深对流过程...全球气候模式BCC-CSM2-MR(Beijing Climate Center-Climate System Model version 2-Medium Resolution)由国家(北京)气候中心自主研发并参与了第六阶段国际耦合模式比较计划,该模式在BCC-CSM1.1m版本基础上对大气辐射传输、深对流过程及重力波等方面进行了优化,因此,该模式对东亚地区降水和气温模拟能力的改进亟需进一步评估。本文主要基于不同格点观测数据集与中国区域站点观测数据,系统对比分析BCC-CSM2-MR、BCC-CSM1.1m两个模式版本对东亚地区季节平均降水(气温)和日极端降水(气温)的模拟能力。结果表明:(1)相比BCC-CSM1.1m,BCC-CSM2-MR改进了对东亚大部分区域季节平均降水的模拟能力,尤其是青藏高原地区夏季平均降水,明显提高了对中国东南地区、朝鲜半岛及日本降水月际变化的模拟性能;(2)BCC-CSM2-MR对东亚地区季节平均气温模拟能力改进不明显,且对东亚大部分区域气温月际变化的模拟误差大于BCC-CSM1.1m;(3)对日极端降水(气温),BCC-CSM2-MR的模拟能力优于BCC-CSM1.1m,明显提高了对中国东南地区日极端降水(气温)的模拟能力。总体而言,BCC-CSM2-MR在深对流过程参数方案中的改进有利于对东亚地区降水的模拟。展开更多
基于东安格里亚大学气候研究中心(Climatic Research Unit,CRU)资料及NCEP/DOE再分析数据集,评估了第六次国际耦合模式比较计划(Coupled Model Intercomparison Project Phase 6,CMIP6)中BCC-CSM2-MR气候模式对东亚冬季风(East Asian Wi...基于东安格里亚大学气候研究中心(Climatic Research Unit,CRU)资料及NCEP/DOE再分析数据集,评估了第六次国际耦合模式比较计划(Coupled Model Intercomparison Project Phase 6,CMIP6)中BCC-CSM2-MR气候模式对东亚冬季风(East Asian Winter Monsoom,EAWM)气候特征的模拟能力.结果表明:BCC-CSM2-MR模式能够合理再现西伯利亚高压、阿留申低压、850 hPa偏北风、500 hPa东亚大槽及200 hPa东亚西风急流等EAWM环流系统的气候态分布.其中,BCC-CSM2-MR模式对500 hPa高度场的模拟效果最好.BCC-CSM2-MR模式能够捕捉EAWM的年际变化及年代际减弱趋势,但是模式中EAWM的减弱趋势小于观测结果.模式能够模拟出EAWM异常对应的西伯利亚高压异常及阿留申低压异常,但是由于高低压异常中心位置与观测资料的差异,导致模式中EAWM异常对应的东亚低层北风异常相对观测结果偏弱,2 m气温负异常也较观测结果偏弱.展开更多
In this study,the performance of the Beijing Climate Center(BCC)Climate System Model version 1.1(BCCCSM1.1)(280-km resolution)and the BCC-CSM1.1 m(110-km resolution)in simulating extreme climate events over China in t...In this study,the performance of the Beijing Climate Center(BCC)Climate System Model version 1.1(BCCCSM1.1)(280-km resolution)and the BCC-CSM1.1 m(110-km resolution)in simulating extreme climate events over China in the last 40 years is compared.Both models capture the main spatial distribution features of heavy precipitation(R95T),the number of consecutive wet days(CWD),the annual count of days with precipitation≥1 mm(R1),the maximum consecutive 5-day precipitation(Rx5),and the numbers of frost days(FD)and summer days(SU).The BCC-CSM1.1 m has a better ability to simulate the detailed distribution of extreme climate events than the BCCCSM1.1,including R95T,CWD,R1,and the simple precipitation intensity index(SDII).However,the BCCCSM 1.1 m does not show an improvement in simulating the number of days with extreme precipitation(R90N),the number of consecutive dry days(CDD),the heat wave duration index(HWDI),the warm day frequency(TX90 P),and cold night frequency(TN10P).This indicates that the simulation of the R95T,CWD,R1,and SDII climate events is more sensitive to the resolution of the model.The improved BCC-CSM1.1 m is used to explore the projection of extreme climate change in China during the 21 st century under the RCP4.5(Representative Concentration Pathways)and RCP8.5 scenarios.The results show that extreme precipitation will increase dramatically over North and Southwest China in the late 21 st century.The CWD index will decrease on the Tibetan Plateau and in northeastern and central China and will increase in other parts of China;R1 will increase in northern China and decrease in southern China;Rx5 will increase dramatically in southern China;FD will decrease and SU will increase over China in the late 21 st century under both emission scenarios,with larger amplitudes in RCP8.5.展开更多
Climate sensitivity represents the response of climate system to doubled CO2 concentration relative to the preindustrial level, which is one of the sources of uncertainty in climate projections. It is unclear how the ...Climate sensitivity represents the response of climate system to doubled CO2 concentration relative to the preindustrial level, which is one of the sources of uncertainty in climate projections. It is unclear how the climate sensitivity and feedbacks will change as a model system is upgraded from the Coupled Model Intercomparison Project Phase 5(CMIP5) to CMIP6. In this paper, we address this issue by comparing two versions of the Beijing Climate Center Climate System Model(BCC-CSM) participating in CMIP6 and CMIP5, i.e., BCC-CSM2-MR and BCC-CSM1.1 m,which have the same horizontal resolution but different physical parameterizations. The results show that the equilibrium climate sensitivity(ECS) of BCC-CSM slightly increases from CMIP5(2.94 K) to CMIP6(3.04 K). The small changes in the ECS result from compensation between decreased effective radiative forcing(ERF) and the increased net feedback. In contrast, the transient climate response(TCR) evidently decreases from 2.19 to 1.40 K, nearly the lower bound of the CMIP6 multimodel spread. The low TCR in BCC-CSM2-MR is mainly caused by the small ERF overly even though the ocean heat uptake(OHU) efficiency is substantially improved from that in BCC-CSM1.1 m.Cloud shortwave feedback(λSWCL) is found to be the major cause of the increased net feedback in BCC-CSM2-MR,mainly over the Southern Ocean. The strong positive λSWCL in BCC-CSM2-MR is coincidently related to the weakened sea ice-albedo feedback in the same region. This result is caused by reduced sea ice coverage simulated during the preindustrial cold season, which leads to reduced melting per 1-K global warming. As a result, in BCCCSM2-MR, reduced surface heat flux and strengthened static stability of the planetary boundary layer cause a decrease in low-level clouds and an increase in incident shortwave radiation. This study reveals the important compensation between λSWCL and sea ice-albedo feedback in the Southern Ocean.展开更多
We evaluated the ability of the Beijing Climate Center models on different horizontal resolutions(BCC-CSM1.1 on approximately 280-km resolution and BCC-CSM1.1 m on approximately 110-km resolution) in simulating the ne...We evaluated the ability of the Beijing Climate Center models on different horizontal resolutions(BCC-CSM1.1 on approximately 280-km resolution and BCC-CSM1.1 m on approximately 110-km resolution) in simulating the nearsurface wind speeds(NWS) in China during 1961–2005. The spatial distribution of the annual mean NWS over China is better captured by BCC-CSM1.1 m than by BCC-CSM1.1 due to the finer resolution. The weakened NWS over China during 1961–2005 cannot be reproduced by BCC-CSM1.1, whereas BCC-CSM1.1 m is able to simulate the decreasing trend of the autumn NWS in North China, although the magnitude is about 1/3 of the observed value.This is attributed to the better performance of this finer-resolution model in reproducing the increase in sea level pressure over Mongolia and North China over the past 45 years. The results suggest that increasing the horizontal resolution of the BCC-CSM model has improved its ability in reproducing the spatial distribution and long-term changes of NWS over China. Future projections by BCC-CSM1.1 m under different Representative Concentration Pathway(RCP) scenarios demonstrate that the autumn NWS in North China will decrease during the 21 st century under both the middle(RCP4.5) and high(RCP8.5) emission scenarios, with a higher decreasing rate under RCP8.5.展开更多
Based on the results of the complex climate model BCC-CSM,the Beijing Climate Center Simple Earth System Model(BCC-SESM)was developed for climate system simulations in Integrated Assessment Models(IAMs).The first vers...Based on the results of the complex climate model BCC-CSM,the Beijing Climate Center Simple Earth System Model(BCC-SESM)was developed for climate system simulations in Integrated Assessment Models(IAMs).The first version of the BCC-SESM model was based on a high-emissions scenario(ESMRCP8.5)and tends to overestimate the temperatures in low and medium emissions scenarios.To address this problem,this study uses three CO_(2)-concentration-driven simulations under different RCP scenarios of complex climate models to evaluate parameters sensitivity and their impacts on projection efficacy.The results show that the new version of the BCC-SESM(denoted as BCC-SESM1.1)model based on a medium-emissions scenario experiment(RCP4.5)is more suitable for temperature projections for various climate scenarios.It can well reproduce the original value of complex climate model.At the same time,it also has high predictive efficacies for medium(RCP4.5)and low(RCP2.6)emissions scenarios,although it tends to underestimate for high emissions scenario(RCP8.5).The sensitivity tests for different RCP scenarios shows that the BCC-SESM1.1 has higher efficacy in projections of future climate change than those model versions based on the other scenarios.The projection deviations for the global average temperature by the BCC-SESM1.1(<2%)are better than the previous BCC-SESM(<5%).In light of recent progress in climate policy,the BCC-SESM1.1 is hence more suitable for coupling with IAMs for the purposes of assessing climate outcomes.展开更多
利用IPCC AR5中BCC-CSM1.1(Beijing Climate Center Climate System Model version 1.1)的历史试验和4类典型排放路径情景下未来预估试验结果,在使用CRU(Climatic Research Unit)资料验证BCC-CSM1.1性能的基础上,采用趋势分析、滑动平...利用IPCC AR5中BCC-CSM1.1(Beijing Climate Center Climate System Model version 1.1)的历史试验和4类典型排放路径情景下未来预估试验结果,在使用CRU(Climatic Research Unit)资料验证BCC-CSM1.1性能的基础上,采用趋势分析、滑动平均以及经验正交函数(EOF)等方法,研究2011—2060年中亚地区年平均气温的时空演变特征。与CRU资料的对比分析发现BCC-CSM1.1能较好地模拟过去109 a(1901—2009年)中亚地区气温的显著上升趋势及气候态的空间分布特征。预估试验结果表明,中亚地区在未来50 a整体呈现变暖趋势,并且,随着温室气体排放浓度的升高,气温的升高趋势愈加明显,同时增温显著区域也明显增大。经验正交函数分解主要模态还是延续过去的分布特征:经验正交函数分解第1模态及其所对应的时问系数显示中亚地区年平均地面气温在未来50 a(2011—2060年)呈现出全场一致的升高趋势,升高强度随着温室气体排放浓度的增加而增强,进一步的分析表明,不同典型排放路径下预估的未来50 a中亚地区年平均地面气温的经验正交函数分解第1模态在中亚上空850 hPa等压面上均对应有一个反气旋(气旋)性异常环流,在这个异常环流控制下,中亚地区年平均地面气温变化表现为全场一致的特征。经验正交函数分解第2模态呈现出中亚地区地面气温变化南北反位相的基本特征,相应的时间系数主要表现为小幅度波动,变化趋势特征不明显。展开更多
This study provides a comprehensive evaluation of historical surface soil moisture simulation(1979-2012)over Eurasia at annual and seasonal time scales between two medium-resolution versions of the Beijing Climate Cen...This study provides a comprehensive evaluation of historical surface soil moisture simulation(1979-2012)over Eurasia at annual and seasonal time scales between two medium-resolution versions of the Beijing Climate Center Climate System Model(BCC-CSM)—one that is currently participating in phase 6 of the Coupled Model Intercomparison Project(CMIP6),i.e.,BCC-CSM2-MR,and the other,BCC-CSM1.1m,which participated in CMIP5.We show that BCC-CSM2-MR is more skillful in reproducing the climate mean states and standard deviations of soil moisture,with pattern correlations increased and biases reduced significantly.BCC-CSM2-MR performs better in capturing the first two primary patterns of soil moisture anomalies,where the period of the corresponding time series is closer to that of reference data.Comparisons show that BCC-CSM2-MR performs at a high level among multiple models of CMIP6 in terms of centered pattern correlation and“amplitude of variation”(relative standard deviation).In general,the centered pattern correlation of BCC-CSM2-MR,ranging from 0.61 to 0.87,is higher than the multi-model mean of CMIP6,and the relative standard deviation is 0.75,which surmounts the overestimations in most of the CMIP6 models.Due to the vital role played by precipitation in land-atmosphere interaction,possible causes of the improvement of soil moisture simulation are further related to precipitation in BCC-CSM2-MR.The results indicate that a better description of the relationship between soil moisture and precipitation and a better reproduction of the climate mean precipitation by the model may result in the improved performance of soil moisture simulation.展开更多
文摘全球气候模式BCC-CSM2-MR(Beijing Climate Center-Climate System Model version 2-Medium Resolution)由国家(北京)气候中心自主研发并参与了第六阶段国际耦合模式比较计划,该模式在BCC-CSM1.1m版本基础上对大气辐射传输、深对流过程及重力波等方面进行了优化,因此,该模式对东亚地区降水和气温模拟能力的改进亟需进一步评估。本文主要基于不同格点观测数据集与中国区域站点观测数据,系统对比分析BCC-CSM2-MR、BCC-CSM1.1m两个模式版本对东亚地区季节平均降水(气温)和日极端降水(气温)的模拟能力。结果表明:(1)相比BCC-CSM1.1m,BCC-CSM2-MR改进了对东亚大部分区域季节平均降水的模拟能力,尤其是青藏高原地区夏季平均降水,明显提高了对中国东南地区、朝鲜半岛及日本降水月际变化的模拟性能;(2)BCC-CSM2-MR对东亚地区季节平均气温模拟能力改进不明显,且对东亚大部分区域气温月际变化的模拟误差大于BCC-CSM1.1m;(3)对日极端降水(气温),BCC-CSM2-MR的模拟能力优于BCC-CSM1.1m,明显提高了对中国东南地区日极端降水(气温)的模拟能力。总体而言,BCC-CSM2-MR在深对流过程参数方案中的改进有利于对东亚地区降水的模拟。
基金Supported by the National Key Research and Development Program of China(2016YFE0102404)National Natural Science Foundation of China(41875111)+1 种基金Forecasters’ Project of China Meteorological Administration(CMAYBY2018-062 and CMAYBY2019-096)Project for Construction of Chongqing Short-Term Climate Prediction Operational Platform
文摘In this study,the performance of the Beijing Climate Center(BCC)Climate System Model version 1.1(BCCCSM1.1)(280-km resolution)and the BCC-CSM1.1 m(110-km resolution)in simulating extreme climate events over China in the last 40 years is compared.Both models capture the main spatial distribution features of heavy precipitation(R95T),the number of consecutive wet days(CWD),the annual count of days with precipitation≥1 mm(R1),the maximum consecutive 5-day precipitation(Rx5),and the numbers of frost days(FD)and summer days(SU).The BCC-CSM1.1 m has a better ability to simulate the detailed distribution of extreme climate events than the BCCCSM1.1,including R95T,CWD,R1,and the simple precipitation intensity index(SDII).However,the BCCCSM 1.1 m does not show an improvement in simulating the number of days with extreme precipitation(R90N),the number of consecutive dry days(CDD),the heat wave duration index(HWDI),the warm day frequency(TX90 P),and cold night frequency(TN10P).This indicates that the simulation of the R95T,CWD,R1,and SDII climate events is more sensitive to the resolution of the model.The improved BCC-CSM1.1 m is used to explore the projection of extreme climate change in China during the 21 st century under the RCP4.5(Representative Concentration Pathways)and RCP8.5 scenarios.The results show that extreme precipitation will increase dramatically over North and Southwest China in the late 21 st century.The CWD index will decrease on the Tibetan Plateau and in northeastern and central China and will increase in other parts of China;R1 will increase in northern China and decrease in southern China;Rx5 will increase dramatically in southern China;FD will decrease and SU will increase over China in the late 21 st century under both emission scenarios,with larger amplitudes in RCP8.5.
基金Supported by the National Key Research and Development Program of China (2016YFA0602602 and 2017YFA0603503)National Natural Science Foundation of China (41605057)。
文摘Climate sensitivity represents the response of climate system to doubled CO2 concentration relative to the preindustrial level, which is one of the sources of uncertainty in climate projections. It is unclear how the climate sensitivity and feedbacks will change as a model system is upgraded from the Coupled Model Intercomparison Project Phase 5(CMIP5) to CMIP6. In this paper, we address this issue by comparing two versions of the Beijing Climate Center Climate System Model(BCC-CSM) participating in CMIP6 and CMIP5, i.e., BCC-CSM2-MR and BCC-CSM1.1 m,which have the same horizontal resolution but different physical parameterizations. The results show that the equilibrium climate sensitivity(ECS) of BCC-CSM slightly increases from CMIP5(2.94 K) to CMIP6(3.04 K). The small changes in the ECS result from compensation between decreased effective radiative forcing(ERF) and the increased net feedback. In contrast, the transient climate response(TCR) evidently decreases from 2.19 to 1.40 K, nearly the lower bound of the CMIP6 multimodel spread. The low TCR in BCC-CSM2-MR is mainly caused by the small ERF overly even though the ocean heat uptake(OHU) efficiency is substantially improved from that in BCC-CSM1.1 m.Cloud shortwave feedback(λSWCL) is found to be the major cause of the increased net feedback in BCC-CSM2-MR,mainly over the Southern Ocean. The strong positive λSWCL in BCC-CSM2-MR is coincidently related to the weakened sea ice-albedo feedback in the same region. This result is caused by reduced sea ice coverage simulated during the preindustrial cold season, which leads to reduced melting per 1-K global warming. As a result, in BCCCSM2-MR, reduced surface heat flux and strengthened static stability of the planetary boundary layer cause a decrease in low-level clouds and an increase in incident shortwave radiation. This study reveals the important compensation between λSWCL and sea ice-albedo feedback in the Southern Ocean.
基金Supported by the National Key Research and Development Program of China(2016YFE0102400 and 2016YFC0202100)
文摘We evaluated the ability of the Beijing Climate Center models on different horizontal resolutions(BCC-CSM1.1 on approximately 280-km resolution and BCC-CSM1.1 m on approximately 110-km resolution) in simulating the nearsurface wind speeds(NWS) in China during 1961–2005. The spatial distribution of the annual mean NWS over China is better captured by BCC-CSM1.1 m than by BCC-CSM1.1 due to the finer resolution. The weakened NWS over China during 1961–2005 cannot be reproduced by BCC-CSM1.1, whereas BCC-CSM1.1 m is able to simulate the decreasing trend of the autumn NWS in North China, although the magnitude is about 1/3 of the observed value.This is attributed to the better performance of this finer-resolution model in reproducing the increase in sea level pressure over Mongolia and North China over the past 45 years. The results suggest that increasing the horizontal resolution of the BCC-CSM model has improved its ability in reproducing the spatial distribution and long-term changes of NWS over China. Future projections by BCC-CSM1.1 m under different Representative Concentration Pathway(RCP) scenarios demonstrate that the autumn NWS in North China will decrease during the 21 st century under both the middle(RCP4.5) and high(RCP8.5) emission scenarios, with a higher decreasing rate under RCP8.5.
基金funded by National Natural Science Foundation of China(42175171)National Key R&D Program of China(2016YFA0602602)Public Welfare Meteo-rology Research Project(GYHY201506023).
文摘Based on the results of the complex climate model BCC-CSM,the Beijing Climate Center Simple Earth System Model(BCC-SESM)was developed for climate system simulations in Integrated Assessment Models(IAMs).The first version of the BCC-SESM model was based on a high-emissions scenario(ESMRCP8.5)and tends to overestimate the temperatures in low and medium emissions scenarios.To address this problem,this study uses three CO_(2)-concentration-driven simulations under different RCP scenarios of complex climate models to evaluate parameters sensitivity and their impacts on projection efficacy.The results show that the new version of the BCC-SESM(denoted as BCC-SESM1.1)model based on a medium-emissions scenario experiment(RCP4.5)is more suitable for temperature projections for various climate scenarios.It can well reproduce the original value of complex climate model.At the same time,it also has high predictive efficacies for medium(RCP4.5)and low(RCP2.6)emissions scenarios,although it tends to underestimate for high emissions scenario(RCP8.5).The sensitivity tests for different RCP scenarios shows that the BCC-SESM1.1 has higher efficacy in projections of future climate change than those model versions based on the other scenarios.The projection deviations for the global average temperature by the BCC-SESM1.1(<2%)are better than the previous BCC-SESM(<5%).In light of recent progress in climate policy,the BCC-SESM1.1 is hence more suitable for coupling with IAMs for the purposes of assessing climate outcomes.
文摘利用IPCC AR5中BCC-CSM1.1(Beijing Climate Center Climate System Model version 1.1)的历史试验和4类典型排放路径情景下未来预估试验结果,在使用CRU(Climatic Research Unit)资料验证BCC-CSM1.1性能的基础上,采用趋势分析、滑动平均以及经验正交函数(EOF)等方法,研究2011—2060年中亚地区年平均气温的时空演变特征。与CRU资料的对比分析发现BCC-CSM1.1能较好地模拟过去109 a(1901—2009年)中亚地区气温的显著上升趋势及气候态的空间分布特征。预估试验结果表明,中亚地区在未来50 a整体呈现变暖趋势,并且,随着温室气体排放浓度的升高,气温的升高趋势愈加明显,同时增温显著区域也明显增大。经验正交函数分解主要模态还是延续过去的分布特征:经验正交函数分解第1模态及其所对应的时问系数显示中亚地区年平均地面气温在未来50 a(2011—2060年)呈现出全场一致的升高趋势,升高强度随着温室气体排放浓度的增加而增强,进一步的分析表明,不同典型排放路径下预估的未来50 a中亚地区年平均地面气温的经验正交函数分解第1模态在中亚上空850 hPa等压面上均对应有一个反气旋(气旋)性异常环流,在这个异常环流控制下,中亚地区年平均地面气温变化表现为全场一致的特征。经验正交函数分解第2模态呈现出中亚地区地面气温变化南北反位相的基本特征,相应的时间系数主要表现为小幅度波动,变化趋势特征不明显。
基金supported by the National Key Research and Development Program of China(Grant Nos.2018YFC1506004 and 2016YFA0602602).
文摘This study provides a comprehensive evaluation of historical surface soil moisture simulation(1979-2012)over Eurasia at annual and seasonal time scales between two medium-resolution versions of the Beijing Climate Center Climate System Model(BCC-CSM)—one that is currently participating in phase 6 of the Coupled Model Intercomparison Project(CMIP6),i.e.,BCC-CSM2-MR,and the other,BCC-CSM1.1m,which participated in CMIP5.We show that BCC-CSM2-MR is more skillful in reproducing the climate mean states and standard deviations of soil moisture,with pattern correlations increased and biases reduced significantly.BCC-CSM2-MR performs better in capturing the first two primary patterns of soil moisture anomalies,where the period of the corresponding time series is closer to that of reference data.Comparisons show that BCC-CSM2-MR performs at a high level among multiple models of CMIP6 in terms of centered pattern correlation and“amplitude of variation”(relative standard deviation).In general,the centered pattern correlation of BCC-CSM2-MR,ranging from 0.61 to 0.87,is higher than the multi-model mean of CMIP6,and the relative standard deviation is 0.75,which surmounts the overestimations in most of the CMIP6 models.Due to the vital role played by precipitation in land-atmosphere interaction,possible causes of the improvement of soil moisture simulation are further related to precipitation in BCC-CSM2-MR.The results indicate that a better description of the relationship between soil moisture and precipitation and a better reproduction of the climate mean precipitation by the model may result in the improved performance of soil moisture simulation.
