Based on 18 global climate models' simulations of the 20th century climate, a set of experiments within phase five of the Coupled Model Inter-comparison Project (CMIP5), the performances of simulating the present ...Based on 18 global climate models' simulations of the 20th century climate, a set of experiments within phase five of the Coupled Model Inter-comparison Project (CMIP5), the performances of simulating the present climate over China are assessed. Compared with observations, models can capture the dominant features of the geographic distributions of temperature and precipitation during 1961-2005. For the temporal changes of temperature, models appear to have a good performance on reproducing the warming tendency but show limited skills for precipitation. For the regional mean temperature and precipitation over the whole of China, most models underestimate the actual temperature and overestimate precipitation. Concerning the standard deviations of simulations by the 18 models, they are larger for temperature in the western part of China, while the standard deviations are larger for precipitation in the South.展开更多
Climate change in the 21st century over China is simulated using the Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model version 3 (RegCM3). The model is one-way nested within the gl...Climate change in the 21st century over China is simulated using the Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model version 3 (RegCM3). The model is one-way nested within the global model CCSR/NIES/FRCGC MIROC3.2_hires (Center for Climate System Research/National Institute for Environmental Studies/Frontier Research Center for Global Change/Model for Interdisciplinary Research on Climate). A 150-year (1951-2100) transient simulation is conducted at 25 km grid spacing, under the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) A1B scenario. Simulations of present climate conditions in China by RegCM3 are compared against observations to assess model performance. Results show that RegCM3 reproduces the observed spatial structure of surface air temperature and precipitation well. Changes in mean temperature and precipitation in December-January-February (DJF) and June-July-August (JJA) during the middle and end of the 21st century are analyzed. Significant future warming is simulated by RegCM3. This warming becomes greater with time, and increased warming is simulated at high latitude and high altitude (Tibetan Plateau) areas. In the middle of the 21st century in DJF, a general increase of precipitation is found in most areas, except over the Tibetan Plateau. Precipitation changes in JJA show an increase over northwest China and a decrease over the Tibetan Plateau. There is a mixture of positive and negative changes in eastern China. The change pattern at the end of the century is generally consistent with that in mid century, except in some small areas, and the magnitude of change is usually larger. In addition, the simulation is compared with a previous simulation of the RegCM3 driven by a different global model, to address uncertainties of the projected climate change in China.展开更多
This paper describes a dynamical downscaling simulation over China using the nested model system,which consists of the modified Weather Research and Forecasting Model(WRF)nested with the NCAR Community Atmosphere Mode...This paper describes a dynamical downscaling simulation over China using the nested model system,which consists of the modified Weather Research and Forecasting Model(WRF)nested with the NCAR Community Atmosphere Model(CAM).Results show that dynamical downscaling is of great value in improving the model simulation of regional climatic characteristics.WRF simulates regional detailed temperature features better than CAM.With the spatial correlation coefficient between the observation and the simulation increasing from 0.54 for CAM to 0.79 for WRF,the improvement in precipitation simulation is more perceptible with WRF.Furthermore,the WRF simulation corrects the spatial bias of the precipitation in the CAM simulation.展开更多
To compare differences among the Medieval Warm Period (MWP), Little Ice Age (LIA), and 20th century global warming (20CW), six sets of transient and equilibrium simulations were generated using the climate system mode...To compare differences among the Medieval Warm Period (MWP), Little Ice Age (LIA), and 20th century global warming (20CW), six sets of transient and equilibrium simulations were generated using the climate system model FGOALS_gl. This model was developed by the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences. The results indicate that MWP warming is evident on a global scale, except for at mid-latitudes of the North Pacific. However, the magnitude of the warming is weaker than that in the 20th century. The warming in the high latitudes of the Northern Hemisphere is stronger than that in the Southern Hemisphere. The LIA cooling is also evident on a global scale, with a strong cooling over the high Eurasian continent, while the cooling center is over the Arctic domain. Both the MWP and the 20CW experiments exhibit the strongest warming anomalies in the middle troposphere around 200-300 hPa, but the cooling center of the LIA experiment is seen in the polar surface of the Northern Hemisphere. A comparison of model simulation against the reconstruction indicates that model's performance in simulating the surface air temperature changes during the warm periods is better than that during the cold periods. The consistencies between model and reconstruction in lower latitudes are better than those in high latitudes. Comparison of the inter-annual variability mode of East Asian summer monsoon (EASM) rainfall during the MWP, LIA and 20CW reveals a similar rainfall anomalies pattern. However, the time spectra of the principal component during the three typical periods of the last millennium are different, and the quasi-biannual oscillation is more evident during the two warm periods. At a centennial time scale, the external mode of the EASM variability driven by the changes of effective solar radiation is determined by the changes of large scale land-sea thermal contrast. The rainfall anomalies over the east of 1展开更多
Ozone pollution over the Pearl River Delta (PRD) in October 2004 has been simulated using the regional air quality models Models-3/CMAQ and CAMx. The results from both models were evaluated and compared with the obser...Ozone pollution over the Pearl River Delta (PRD) in October 2004 has been simulated using the regional air quality models Models-3/CMAQ and CAMx. The results from both models were evaluated and compared with the observed concentrations from 12 monitoring stations. By integrated process rate analysis, the influences of different physical and chemical processes were quantified, and the causes of the deviations between the two models were investigated. Both CMAQ and CAMx repro- duced the magnitudes and variations of ozone at most stations over the PRD. The correlation coefficients (R) between the sim- ulated results and monitoring data were 0.73 for CMAQ and 0.74 for CAMx. The normalized mean bias (NMB) for CMAQ and CAMx over the 12 sites was ?8.5% and 8.8% on average, respectively. The normalized mean error (NME) for CMAQ and CAMx was 36.7% and 37.9%, respectively. The correlation between the results of two models was very high (R = 0.92), and their simulated ozone spatial distributions exhibited common features. But the values obtained using CMAQ simulation were about 17% lower than those obtained using CAMx on average. The results of simulations using the two models were not identical in certain regions, or for different types of monitoring stations. The differences in dry deposition, reaction parameters and vertical transport near the Pearl River Estuary can account for the discrepancies in the results obtained using the two models. In the upwind areas, the discrepancy in the boundary concentration of the finest nest was the main cause of the higher values obtained using CAMx compared with those obtained using CMAQ. There is a need for CAMx to provide more choices of dry deposition algo- rithms. Improvement of the calculation methods for photolysis rates would also improve the ozone simulation of CMAQ.展开更多
There is a scientific debate on the relationship between ancient winter and summer monsoons in East Asia.Some scholars think that East Asian winter and summer monsoons are anti-correlated,and others think not.For this...There is a scientific debate on the relationship between ancient winter and summer monsoons in East Asia.Some scholars think that East Asian winter and summer monsoons are anti-correlated,and others think not.For this reason,this study is motivated to assess their linkage from the paleoclimate simulation perspective,through analyzing the Last Glacial Maximum(LGM) and mid-Holocene(MH) climate simulated by CCSM3 model.Compared to the present climate,the Aleutian low is found to be deepened and the East Asian winter monsoon(EAWM) is stronger during the LGM winter.The Pacific high in summer is noticed to be weakened and the East Asian summer monsoon(EASM) is weaker at the LGM.During the MH,the Aleutian low and the Asian high in winter are intensified,and the Asian low and the Pacific high in summer are enhanced,indicating that the EAWM and EASM are both stronger than today.Therefore,the EAWM is not always negatively correlated to the EASM.Their relationship may be different at different geological stages.It can be obtained at least from the numerical simulation results that the EAWM and the EASM is negatively correlated during the cooling period,while positively correlated during the warming period.展开更多
Frequent winter snowstorms have recently caused large economic losses and attracted wide attention.These snowstorms have raised an important scientific question.Under scenarios of future global warming,will winter pre...Frequent winter snowstorms have recently caused large economic losses and attracted wide attention.These snowstorms have raised an important scientific question.Under scenarios of future global warming,will winter precipitation in China increase significantly and produce more snow in the north? Using Coupled Model Intercomparison Project phase 3 (CMIP 3) model projections under the Special Report on Emissions Scenario A1B scenario,we generated a possible future Arctic condition,the summer (September) "ice-free Arctic" condition.We then used corresponding monthly sea surface temperature (SST) values and a set of CO 2 concentrations to drive an atmospheric general circulation model (AGCM),for simulating East Asian climate change.The experimental results show that during the boreal winter (December-January-February;DJF),global surface air temperature would increase significantly under this scenario,producing substantial warming in Arctic regions and at high latitudes in Asia and North America.The Siberian High,Aleutian Low and East Asian winter monsoon would all weaken.However,because of increased transport of water vapor to China from the north,winter precipitation would increase from south to north.In addition,the significant increase in winter temperature might cause fewer cold surges.展开更多
Based on simulations of 18 CMIP5 models under three RCP scenarios, this article investigates changes in mean temperature and precipitation and their extremes over Asia in the context of global warming targets of 1.5-4...Based on simulations of 18 CMIP5 models under three RCP scenarios, this article investigates changes in mean temperature and precipitation and their extremes over Asia in the context of global warming targets of 1.5-4 ℃, and further compares the differences between 1.5 ℃ and 2 ℃ targets. Results show that relative to the pre-industrial era, the mean temperature over Asia increases by 2.3 ℃, 3.0 ℃, 4.6 ℃, and 6.0 ℃ at warming targets of 1.5 ℃, 2 ℃, 3 ℃, and 4 ℃, respectively, with stronger warming in high latitudes than in low latitudes. The corresponding enhancement in mean precipitation over the entire Asian region is 4.4%, 5.8%, 10.2%, and 13.0%, with significant regional differences. In addition, an increase in warm extremes, a decrease in cold extremes, and a strengthening in the variability of amounts of extreme precipitation are projected. Under the 1.5 ℃ target, compared with the climate under the 2 ℃ target, the mean temperature will be lower by 0.5-1 ℃ over Asia; the mean precipitation will be less by 5%-20% over most of Asia, but will be greater by about 10%-15% over West Asia and western South Asia; extreme high temperatures will be uniformly cooler throughout the Asian region, and the warming in extreme low temperatures will decrease significantly in high latitudes of Asia; extreme precipitation will be weaker over most of Asia but will be stronger over West Asia and western South Asia. Under the 1.5 ℃ and 2 ℃ warming targets, the probability of very hot weather （anomalies greater than 1σ, σ is standard deviation）, extremely hot weather （anomalies greater than 3or）, and extremely heavy precipitation （anomalies greater than 3σ） occurring will increase by at least once, 10%, and 10%, respectively, compared to the reference period （1861-1900）.展开更多
Four sets of climate change simulations at grid spacing of 50 km were conducted over East Asia with two regional climate models driven at the lateral bounda- ries by two global models for the period 1981-2050. The loc...Four sets of climate change simulations at grid spacing of 50 km were conducted over East Asia with two regional climate models driven at the lateral bounda- ries by two global models for the period 1981-2050. The locus of the study was on the ensemble projection of cli- mate change in the mid-21st century （2031-50） over China. Validation of each simulation and the ensemble average showed good performances of the models overall, as well as advantages of the ensemble in reproducing present day （1981 2000） December-February （DJF）, June-August （JJA）, and annual （ANN） mean temperature and precipitation. Significant wanning was projected for the mid-21st century, with larger values of temperature increase found in the northern part of China and in the cold seasons. The ensemble average changes of precipitation in DJF, JJA, and ANN were determined, and the uncertainties of the projected changes analyzed based on the consistencies of the simulations. It was concluded that the largest uncertainties in precipitation projection are in eastern China during the summer season （monsoon pre-cipitation）.展开更多
Land cover is one of the most basic input elements of land surface and climate models. Currently, the direct and indirect effects of land cover data on climate and climate change are receiving increasing attentions. I...Land cover is one of the most basic input elements of land surface and climate models. Currently, the direct and indirect effects of land cover data on climate and climate change are receiving increasing attentions. In this study, a high resolution(30 m) global land cover dataset(Globe Land30) produced by Chinese scientists was, for the first time, used in the Beijing Climate Center Climate System Model(BCC_CSM) to assess the influences of land cover dataset on land surface and climate simulations. A two-step strategy was designed to use the Globe Land30 data in the model. First, the Globe Land30 data were merged with other satellite remote sensing and climate datasets to regenerate plant functional type(PFT) data fitted for the BCC_CSM. Second, the up-scaling based on an area-weighted approach was used to aggregate the fine-resolution Globe Land30 land cover type and area percentage with the coarser model grid resolutions globally. The Globe Land30-based and the BCC_CSM-based land cover data had generally consistent spatial distribution features, but there were some differences between them. The simulation results of the different land cover type dataset change experiments showed that effects of the new PFT data were larger than those of the new glaciers and water bodies(lakes and wetlands). The maximum value was attained when dataset of all land cover types were changed. The positive bias of precipitation in the mid-high latitude of the northern hemisphere and the negative bias in the Amazon, as well as the negative bias of air temperature in part of the southern hemisphere, were reduced when the Globe Land30-based data were used in the BCC_CSM atmosphere model. The results suggest that the Globe Land30 data are suitable for use in the BCC_CSM component models and can improve the performance of the land and atmosphere simulations.展开更多
基金supported by the National Natural Science Foundation of China(2009CB421407 and 2010CB950501)
文摘Based on 18 global climate models' simulations of the 20th century climate, a set of experiments within phase five of the Coupled Model Inter-comparison Project (CMIP5), the performances of simulating the present climate over China are assessed. Compared with observations, models can capture the dominant features of the geographic distributions of temperature and precipitation during 1961-2005. For the temporal changes of temperature, models appear to have a good performance on reproducing the warming tendency but show limited skills for precipitation. For the regional mean temperature and precipitation over the whole of China, most models underestimate the actual temperature and overestimate precipitation. Concerning the standard deviations of simulations by the 18 models, they are larger for temperature in the western part of China, while the standard deviations are larger for precipitation in the South.
基金the National Basic Research Program of China (2009CB421407)China-UK-Swiss Adapting to Climate Change in China Project (ACCC)the Special Research Program for Public-welfare Forestry (200804001)
文摘Climate change in the 21st century over China is simulated using the Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model version 3 (RegCM3). The model is one-way nested within the global model CCSR/NIES/FRCGC MIROC3.2_hires (Center for Climate System Research/National Institute for Environmental Studies/Frontier Research Center for Global Change/Model for Interdisciplinary Research on Climate). A 150-year (1951-2100) transient simulation is conducted at 25 km grid spacing, under the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) A1B scenario. Simulations of present climate conditions in China by RegCM3 are compared against observations to assess model performance. Results show that RegCM3 reproduces the observed spatial structure of surface air temperature and precipitation well. Changes in mean temperature and precipitation in December-January-February (DJF) and June-July-August (JJA) during the middle and end of the 21st century are analyzed. Significant future warming is simulated by RegCM3. This warming becomes greater with time, and increased warming is simulated at high latitude and high altitude (Tibetan Plateau) areas. In the middle of the 21st century in DJF, a general increase of precipitation is found in most areas, except over the Tibetan Plateau. Precipitation changes in JJA show an increase over northwest China and a decrease over the Tibetan Plateau. There is a mixture of positive and negative changes in eastern China. The change pattern at the end of the century is generally consistent with that in mid century, except in some small areas, and the magnitude of change is usually larger. In addition, the simulation is compared with a previous simulation of the RegCM3 driven by a different global model, to address uncertainties of the projected climate change in China.
基金supported by the Special Fund for Public Welfare Industry (meteorology) (Grant No. GYHY200906018)the National Basic Research Program of China (973 Program) (Grant No. 2009CB421406)the National Natural Science Foundation of China (Grant Nos. 40875048 and 40821092)
文摘This paper describes a dynamical downscaling simulation over China using the nested model system,which consists of the modified Weather Research and Forecasting Model(WRF)nested with the NCAR Community Atmosphere Model(CAM).Results show that dynamical downscaling is of great value in improving the model simulation of regional climatic characteristics.WRF simulates regional detailed temperature features better than CAM.With the spatial correlation coefficient between the observation and the simulation increasing from 0.54 for CAM to 0.79 for WRF,the improvement in precipitation simulation is more perceptible with WRF.Furthermore,the WRF simulation corrects the spatial bias of the precipitation in the CAM simulation.
基金the National Natural Science Foundation of China (40890054)
文摘To compare differences among the Medieval Warm Period (MWP), Little Ice Age (LIA), and 20th century global warming (20CW), six sets of transient and equilibrium simulations were generated using the climate system model FGOALS_gl. This model was developed by the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences. The results indicate that MWP warming is evident on a global scale, except for at mid-latitudes of the North Pacific. However, the magnitude of the warming is weaker than that in the 20th century. The warming in the high latitudes of the Northern Hemisphere is stronger than that in the Southern Hemisphere. The LIA cooling is also evident on a global scale, with a strong cooling over the high Eurasian continent, while the cooling center is over the Arctic domain. Both the MWP and the 20CW experiments exhibit the strongest warming anomalies in the middle troposphere around 200-300 hPa, but the cooling center of the LIA experiment is seen in the polar surface of the Northern Hemisphere. A comparison of model simulation against the reconstruction indicates that model's performance in simulating the surface air temperature changes during the warm periods is better than that during the cold periods. The consistencies between model and reconstruction in lower latitudes are better than those in high latitudes. Comparison of the inter-annual variability mode of East Asian summer monsoon (EASM) rainfall during the MWP, LIA and 20CW reveals a similar rainfall anomalies pattern. However, the time spectra of the principal component during the three typical periods of the last millennium are different, and the quasi-biannual oscillation is more evident during the two warm periods. At a centennial time scale, the external mode of the EASM variability driven by the changes of effective solar radiation is determined by the changes of large scale land-sea thermal contrast. The rainfall anomalies over the east of 1
基金supported by theNational High Technology Research and Development Program of China (2006AA06A306 & 2006AA06A308)a special fund of the State Key Joint Laboratory of Environmental Simulation and Pollution Controlthe European Commission Framework Program 7 Project CityZen (212095)
文摘Ozone pollution over the Pearl River Delta (PRD) in October 2004 has been simulated using the regional air quality models Models-3/CMAQ and CAMx. The results from both models were evaluated and compared with the observed concentrations from 12 monitoring stations. By integrated process rate analysis, the influences of different physical and chemical processes were quantified, and the causes of the deviations between the two models were investigated. Both CMAQ and CAMx repro- duced the magnitudes and variations of ozone at most stations over the PRD. The correlation coefficients (R) between the sim- ulated results and monitoring data were 0.73 for CMAQ and 0.74 for CAMx. The normalized mean bias (NMB) for CMAQ and CAMx over the 12 sites was ?8.5% and 8.8% on average, respectively. The normalized mean error (NME) for CMAQ and CAMx was 36.7% and 37.9%, respectively. The correlation between the results of two models was very high (R = 0.92), and their simulated ozone spatial distributions exhibited common features. But the values obtained using CMAQ simulation were about 17% lower than those obtained using CAMx on average. The results of simulations using the two models were not identical in certain regions, or for different types of monitoring stations. The differences in dry deposition, reaction parameters and vertical transport near the Pearl River Estuary can account for the discrepancies in the results obtained using the two models. In the upwind areas, the discrepancy in the boundary concentration of the finest nest was the main cause of the higher values obtained using CAMx compared with those obtained using CMAQ. There is a need for CAMx to provide more choices of dry deposition algo- rithms. Improvement of the calculation methods for photolysis rates would also improve the ozone simulation of CMAQ.
基金Supported by the National Basic Research Program of China (Grant Nos. 2007CB 815901 and 2009CB421407)
文摘There is a scientific debate on the relationship between ancient winter and summer monsoons in East Asia.Some scholars think that East Asian winter and summer monsoons are anti-correlated,and others think not.For this reason,this study is motivated to assess their linkage from the paleoclimate simulation perspective,through analyzing the Last Glacial Maximum(LGM) and mid-Holocene(MH) climate simulated by CCSM3 model.Compared to the present climate,the Aleutian low is found to be deepened and the East Asian winter monsoon(EAWM) is stronger during the LGM winter.The Pacific high in summer is noticed to be weakened and the East Asian summer monsoon(EASM) is weaker at the LGM.During the MH,the Aleutian low and the Asian high in winter are intensified,and the Asian low and the Pacific high in summer are enhanced,indicating that the EAWM and EASM are both stronger than today.Therefore,the EAWM is not always negatively correlated to the EASM.Their relationship may be different at different geological stages.It can be obtained at least from the numerical simulation results that the EAWM and the EASM is negatively correlated during the cooling period,while positively correlated during the warming period.
基金supported by the National Basic Research Program of China (2009CB421406)the National Natural Science Foundation of China (41130103)Norwegian Research Council Project "East-Asia DecCen"
文摘Frequent winter snowstorms have recently caused large economic losses and attracted wide attention.These snowstorms have raised an important scientific question.Under scenarios of future global warming,will winter precipitation in China increase significantly and produce more snow in the north? Using Coupled Model Intercomparison Project phase 3 (CMIP 3) model projections under the Special Report on Emissions Scenario A1B scenario,we generated a possible future Arctic condition,the summer (September) "ice-free Arctic" condition.We then used corresponding monthly sea surface temperature (SST) values and a set of CO 2 concentrations to drive an atmospheric general circulation model (AGCM),for simulating East Asian climate change.The experimental results show that during the boreal winter (December-January-February;DJF),global surface air temperature would increase significantly under this scenario,producing substantial warming in Arctic regions and at high latitudes in Asia and North America.The Siberian High,Aleutian Low and East Asian winter monsoon would all weaken.However,because of increased transport of water vapor to China from the north,winter precipitation would increase from south to north.In addition,the significant increase in winter temperature might cause fewer cold surges.
基金Acknowledgments This research was jointly supported by the National Key Research and Development Program of China （2016YFA0600701）, the National Natural Science Foundation of China （41675069）, and the Climate Change Specific Fund of China （CCSF201731）.
文摘Based on simulations of 18 CMIP5 models under three RCP scenarios, this article investigates changes in mean temperature and precipitation and their extremes over Asia in the context of global warming targets of 1.5-4 ℃, and further compares the differences between 1.5 ℃ and 2 ℃ targets. Results show that relative to the pre-industrial era, the mean temperature over Asia increases by 2.3 ℃, 3.0 ℃, 4.6 ℃, and 6.0 ℃ at warming targets of 1.5 ℃, 2 ℃, 3 ℃, and 4 ℃, respectively, with stronger warming in high latitudes than in low latitudes. The corresponding enhancement in mean precipitation over the entire Asian region is 4.4%, 5.8%, 10.2%, and 13.0%, with significant regional differences. In addition, an increase in warm extremes, a decrease in cold extremes, and a strengthening in the variability of amounts of extreme precipitation are projected. Under the 1.5 ℃ target, compared with the climate under the 2 ℃ target, the mean temperature will be lower by 0.5-1 ℃ over Asia; the mean precipitation will be less by 5%-20% over most of Asia, but will be greater by about 10%-15% over West Asia and western South Asia; extreme high temperatures will be uniformly cooler throughout the Asian region, and the warming in extreme low temperatures will decrease significantly in high latitudes of Asia; extreme precipitation will be weaker over most of Asia but will be stronger over West Asia and western South Asia. Under the 1.5 ℃ and 2 ℃ warming targets, the probability of very hot weather （anomalies greater than 1σ, σ is standard deviation）, extremely hot weather （anomalies greater than 3or）, and extremely heavy precipitation （anomalies greater than 3σ） occurring will increase by at least once, 10%, and 10%, respectively, compared to the reference period （1861-1900）.
基金supported by the R&D Special Fund for Public Welfare Industry (Meteorology) (Grant No. GYHY201306019)the National Natural Science Foundation of China (Grant No. 41375104)the China-UK-Swiss Adapting to Climate Change in China Project (ACCC)-Climate Science
文摘Four sets of climate change simulations at grid spacing of 50 km were conducted over East Asia with two regional climate models driven at the lateral bounda- ries by two global models for the period 1981-2050. The locus of the study was on the ensemble projection of cli- mate change in the mid-21st century （2031-50） over China. Validation of each simulation and the ensemble average showed good performances of the models overall, as well as advantages of the ensemble in reproducing present day （1981 2000） December-February （DJF）, June-August （JJA）, and annual （ANN） mean temperature and precipitation. Significant wanning was projected for the mid-21st century, with larger values of temperature increase found in the northern part of China and in the cold seasons. The ensemble average changes of precipitation in DJF, JJA, and ANN were determined, and the uncertainties of the projected changes analyzed based on the consistencies of the simulations. It was concluded that the largest uncertainties in precipitation projection are in eastern China during the summer season （monsoon pre-cipitation）.
基金supported by the National High Technology Research and Development Program of China (Grant No. 2009AA122005)the Public Welfare Meteorology Research Project of China (Grant Nos. 201506023, 201306048)the National Natural Science Foundation of China (Grant Nos. 41275076, 40905046)
文摘Land cover is one of the most basic input elements of land surface and climate models. Currently, the direct and indirect effects of land cover data on climate and climate change are receiving increasing attentions. In this study, a high resolution(30 m) global land cover dataset(Globe Land30) produced by Chinese scientists was, for the first time, used in the Beijing Climate Center Climate System Model(BCC_CSM) to assess the influences of land cover dataset on land surface and climate simulations. A two-step strategy was designed to use the Globe Land30 data in the model. First, the Globe Land30 data were merged with other satellite remote sensing and climate datasets to regenerate plant functional type(PFT) data fitted for the BCC_CSM. Second, the up-scaling based on an area-weighted approach was used to aggregate the fine-resolution Globe Land30 land cover type and area percentage with the coarser model grid resolutions globally. The Globe Land30-based and the BCC_CSM-based land cover data had generally consistent spatial distribution features, but there were some differences between them. The simulation results of the different land cover type dataset change experiments showed that effects of the new PFT data were larger than those of the new glaciers and water bodies(lakes and wetlands). The maximum value was attained when dataset of all land cover types were changed. The positive bias of precipitation in the mid-high latitude of the northern hemisphere and the negative bias in the Amazon, as well as the negative bias of air temperature in part of the southern hemisphere, were reduced when the Globe Land30-based data were used in the BCC_CSM atmosphere model. The results suggest that the Globe Land30 data are suitable for use in the BCC_CSM component models and can improve the performance of the land and atmosphere simulations.
