This paper describes the construction of a 0.5°× 0.5° daily temperature dataset for the period of 1961- 2005 over China's Mainland for the purpose of climate model validation. The dataset is based o...This paper describes the construction of a 0.5°× 0.5° daily temperature dataset for the period of 1961- 2005 over China's Mainland for the purpose of climate model validation. The dataset is based on the interpolation from 751 observing stations in China and comprises 3 variables： daily mean, minimum, and maximum temperature. The ＂anomaly approach＂ is applied in the interpolation. The gridded climatology of 1971-2000 is first calculated and then a gridded daily anomaly for 1961-2005 is added to the climatology to obtain the final dataset. Comparison of the dataset with CRU （Climatic Research Unit） observations at the monthly scale shows general agreement between the two datasets. The differences found can be largely attributed to the introduction of observations at new stations. The dataset shows similar interannual variability as does CRU data over North China and eastern part of the Tibetan Plateau, but with a slightly larger linear trend. The dataset is employed to validate the simulation of three extreme indices based on daily mean, minimum, and maximum temperature by a high-resolution regional climate model. Results show that the model reproduces these indices well. The data are available at the National Climate Center of China Meteorological Administration, and a coarser resolution （1°× 1°） version can be accessed via the World Wide Web.展开更多
Changes of extreme events due to greenhouse effects (2 × CO<SUB>2</SUB>) over East Asia, with a focus on the China region as simulated by a regional climate model (RegCM2), are investigated. The model...Changes of extreme events due to greenhouse effects (2 × CO<SUB>2</SUB>) over East Asia, with a focus on the China region as simulated by a regional climate model (RegCM2), are investigated. The model is nested to a global coupled ocean-atmosphere model (CSIRO R21L9 AOGCM). Analysis of the control run of the regional model indicates that it can reproduce well the extreme events in China. Statistically significant changes of the events are analyzed. Results show that both daily maximum and daily minimum temperature increase in 2 × CO<SUB>2</SUB> conditions, while the diurnal temperature range decreases. The number of hot spell days increases while the number of cold spell days decreases. The number of rainy days and heavy rain days increases over some sub-regions of China. The 2 × CO<SUB>2</SUB> conditions also cause some changes in the tropical storms affecting China.展开更多
The Nested Air Quality Prediction Model System(NAQPMS)was used to investigate the temporal and spatial variations of PM2.5over tropospheric central eastern China in January 2013.The impact of regional transport and it...The Nested Air Quality Prediction Model System(NAQPMS)was used to investigate the temporal and spatial variations of PM2.5over tropospheric central eastern China in January 2013.The impact of regional transport and its implications on pollution prevention and control were also examined.Comparison between simulated and observed PM2.5showed NAQPMS was able to reproduce the evolution of PM2.5during heavy haze episodes.The results indicated that regional transport of PM2.5played an important role in regional haze episodes in the city cluster including Hebei,Beijing and Tianjin(HBT).The cross-city clusters transport outside HBT and transport among cities inside HBT contributed 20%–35%and 26%–35%of PM2.5as compared with local emission,in HBT respectively.To meet the Air Quality Standards for Grade II,90%,90%and65%of emissions would have to be cut down in Hebei,Tianjin and Beijing,if non-control strategy was taken in the surrounding city clusters of HBT.This implicated that control of emissions in one city cluster is not sufficient to reduce regional haze events,and joint efforts among city clusters are essential.Besides regional transports,two-way feedback between boundary-layer evolution and PM2.5also significantly contributed to the formation of heavy hazes,which contributed 30%of monthly average PM2.5concentration in HBT.展开更多
Driven by the global model,Beijing Climate Center Climate System Model version 1.1(BCC_CSM1.1),climate change over China in the 21st century is simulated by a regional climate model(RegCM4.0)under the new emission sce...Driven by the global model,Beijing Climate Center Climate System Model version 1.1(BCC_CSM1.1),climate change over China in the 21st century is simulated by a regional climate model(RegCM4.0)under the new emission scenarios of the Representative Concentration Pathways—RCP4.5 and RCP8.5.This is based on a period of transient simulations from 1950 to2099,with a grid spacing of 50 km.The present paper focuses on the annual mean temperature and precipitation in China over this period,with emphasis on their future changes.Validation of model performance reveals marked improvement of the RegCM4.0 model in reproducing present day temperature and precipitation relative to the driving BCC_CSM1.1 model.Significant warming is simulated by both BCC_CSM1.1 and RegCM4.0,however,spatial distribution and magnitude differ between the simulations.The high emission scenario RCP8.5 results in greater warming compared to RCP4.5.The two models project different precipitation changes,characterized by a general increase in the BCC_CSM1.1,and broader areas with decrease in the RegCM4.0 simulations.展开更多
This article analyzed the control progress and current status of air quality,identified the major air pollution issues and challenges in future,proposed the long-term air pollution control targets,and suggested the op...This article analyzed the control progress and current status of air quality,identified the major air pollution issues and challenges in future,proposed the long-term air pollution control targets,and suggested the options for better air quality in China.With the continuing growth of economy in the next 10–15 years,China will face a more severe situation of energy consumption,electricity generation and vehicle population leading to increase in multiple pollutant emissions.Controlling regional air pollution especially fine particles and ozone,as well as lowering carbon emissions from fossil fuel consumption will be a big challenge for the country.To protect public health and the eco-system,the ambient air quality in all Chinese cities shall attain the national ambient air quality standards （NAAQS） and ambient air quality guideline values set by the World Health Organization （WHO）.To achieve the air quality targets,the emissions of SO 2,NOx,PM 10,and volatile organic compounds （VOC） should decrease by 60%,40%,50%,and 40%,respectively,on the basis of that in 2005.A comprehensive control policy focusing on multiple pollutants and emission sources at both the local and regional levels was proposed to mitigate the regional air pollution issue in China.The options include development of clean energy resources,promotion of clean and efficient coal use,enhancement of vehicle pollution control,implementation of synchronous control of multiple pollutants including SO 2,NOx,VOC,and PM emissions,joint prevention and control of regional air pollution,and application of climate friendly air pollution control measures.展开更多
We relocated M8.0 Wenchuan earthquake and 2706 aftershocks with M≥2.0 using double-difference algorithm and obtained relocations of 2553 events. To reduce the influence of lateral variation in crustal and upper mantl...We relocated M8.0 Wenchuan earthquake and 2706 aftershocks with M≥2.0 using double-difference algorithm and obtained relocations of 2553 events. To reduce the influence of lateral variation in crustal and upper mantle velocity structure, we used different velocity models for the east and west side of Longmenshan fault zone. In the relocation process, we added seismic data from portable seismic sta-tions close to the shocks to constrain focal depths. The precisions in E-W, N-S, and U-D directions after relocation are 0.6, 0.7, and 2.5 km respectively. The relocation results show that the aftershock epi-centers of Wenchuan earthquake were distributed in NE-SW direction, with a total length of about 330 km. The aftershocks were concentrated on the west side of the central fault of Longmenshan fault zone, excluding those on the north of Qingchuan, which obviously deviated from the surface fault and passed through Pingwu-Qingchuan fault in the north. The dominant focal depths of the aftershocks are between 5 and 20 km, the average depth is 13.3 km, and the depth of the relocated main shock is 16.0 km. The depth profile reveals that focal depth distribution in some of the areas is characterized by high-angle westward dipping. The rupture mode of the main shock features reverse faulting in the south, with a large strike-slip component in the north.展开更多
This study analyzed the temporal precipitation variations in the arid Central Asia （ACA） and their regional differences during 1930-2009 using monthly gridded precipitation from the Climatic Research Unit （CRU）. O...This study analyzed the temporal precipitation variations in the arid Central Asia （ACA） and their regional differences during 1930-2009 using monthly gridded precipitation from the Climatic Research Unit （CRU）. Our results showed that the annual precipitation in this westerly circulation dominated arid region is generally increasing during the past 80 years, with an apparent increasing trend （0.7 mm/10 a） in winter. The precipitation variations in ACA also differ regionally, which can be divided into five distinct subregions （Ⅰ West Kazakhstan region, Ⅱ East Kazakhstan region, ⅢCentral Asia Plains region, Ⅳ Kyrgyzstan region, and V Iran Plateau region）. The annual precipitation falls fairly even on all seasons in the two northern subregions （regions Ⅰ and Ⅱ, approximately north of 45°N）, whereas the annual precipitation is falling mainly on winter and spring （accounting for up to 80% of the annual total precipitation） in the three southern subregions. The annual precipitation is increasing on all subregions except the southwestern ACA （subregion Ⅴ） during the past 80 years. A significant increase in precipitation appeared in subregions Ⅰ and Ⅲ. The long-term trends in annual precipitation in all subregions are determined mainly by trends in winter precipitation. Additionally, the precipitation in ACA has significant interannual variations. The 2-3-year cycle is identified in all subregions, while the 5-6-year cycle is also found in the three southern subregions. Besides the inter-annual variations, there were 3-4 episodic precipitation variations in all subregions, with the latest episodic change that started in the mid- to late 1970s. The precipitations in most of the study regions are fast increasing since the late 1970s. Overall, the responses of ACA precipitation to global warming are complicated. The variations of westerly circulation are likely the major factors that influence the precipitation variations in the study region.展开更多
基金supported by the National Basic Research Program of China (2009CB421407,2006CB403707,and2007BAC03A01)the R & D Special Fund for Public Welfare Industry(meteorol-ogy)(GYHY200806010)Chinese Academy of Sciences(Grant NOKZCX2-YW-Q1-02)
文摘This paper describes the construction of a 0.5°× 0.5° daily temperature dataset for the period of 1961- 2005 over China's Mainland for the purpose of climate model validation. The dataset is based on the interpolation from 751 observing stations in China and comprises 3 variables： daily mean, minimum, and maximum temperature. The ＂anomaly approach＂ is applied in the interpolation. The gridded climatology of 1971-2000 is first calculated and then a gridded daily anomaly for 1961-2005 is added to the climatology to obtain the final dataset. Comparison of the dataset with CRU （Climatic Research Unit） observations at the monthly scale shows general agreement between the two datasets. The differences found can be largely attributed to the introduction of observations at new stations. The dataset shows similar interannual variability as does CRU data over North China and eastern part of the Tibetan Plateau, but with a slightly larger linear trend. The dataset is employed to validate the simulation of three extreme indices based on daily mean, minimum, and maximum temperature by a high-resolution regional climate model. Results show that the model reproduces these indices well. The data are available at the National Climate Center of China Meteorological Administration, and a coarser resolution （1°× 1°） version can be accessed via the World Wide Web.
基金Thanks are due to CSIRO in Australia and the Institute of Botany,Chinese Academy of Sciences,National Climate Center of China , for providing the data sets of the GCM and the vegetation coverThis research was supported by the National Natural Science Foundation of China under Grant No, 40125014National Key Programme for Developing Basic Sciences (G1998040900-part 1).
文摘Changes of extreme events due to greenhouse effects (2 × CO<SUB>2</SUB>) over East Asia, with a focus on the China region as simulated by a regional climate model (RegCM2), are investigated. The model is nested to a global coupled ocean-atmosphere model (CSIRO R21L9 AOGCM). Analysis of the control run of the regional model indicates that it can reproduce well the extreme events in China. Statistically significant changes of the events are analyzed. Results show that both daily maximum and daily minimum temperature increase in 2 × CO<SUB>2</SUB> conditions, while the diurnal temperature range decreases. The number of hot spell days increases while the number of cold spell days decreases. The number of rainy days and heavy rain days increases over some sub-regions of China. The 2 × CO<SUB>2</SUB> conditions also cause some changes in the tropical storms affecting China.
基金supported by the CAS Strategic Priority Research Program(Grant Nos.XDB05030200 and XDB05030101)the National Natural Science Foundation of China(Grant No.41278138)
文摘The Nested Air Quality Prediction Model System(NAQPMS)was used to investigate the temporal and spatial variations of PM2.5over tropospheric central eastern China in January 2013.The impact of regional transport and its implications on pollution prevention and control were also examined.Comparison between simulated and observed PM2.5showed NAQPMS was able to reproduce the evolution of PM2.5during heavy haze episodes.The results indicated that regional transport of PM2.5played an important role in regional haze episodes in the city cluster including Hebei,Beijing and Tianjin(HBT).The cross-city clusters transport outside HBT and transport among cities inside HBT contributed 20%–35%and 26%–35%of PM2.5as compared with local emission,in HBT respectively.To meet the Air Quality Standards for Grade II,90%,90%and65%of emissions would have to be cut down in Hebei,Tianjin and Beijing,if non-control strategy was taken in the surrounding city clusters of HBT.This implicated that control of emissions in one city cluster is not sufficient to reduce regional haze events,and joint efforts among city clusters are essential.Besides regional transports,two-way feedback between boundary-layer evolution and PM2.5also significantly contributed to the formation of heavy hazes,which contributed 30%of monthly average PM2.5concentration in HBT.
基金supported by the National Basic Research Program of China (Grant No. 2010CB 950903)the China-UK-Swiss Adapting to Climate Change in China Project (ACCC)-Climate Science
文摘Driven by the global model,Beijing Climate Center Climate System Model version 1.1(BCC_CSM1.1),climate change over China in the 21st century is simulated by a regional climate model(RegCM4.0)under the new emission scenarios of the Representative Concentration Pathways—RCP4.5 and RCP8.5.This is based on a period of transient simulations from 1950 to2099,with a grid spacing of 50 km.The present paper focuses on the annual mean temperature and precipitation in China over this period,with emphasis on their future changes.Validation of model performance reveals marked improvement of the RegCM4.0 model in reproducing present day temperature and precipitation relative to the driving BCC_CSM1.1 model.Significant warming is simulated by both BCC_CSM1.1 and RegCM4.0,however,spatial distribution and magnitude differ between the simulations.The high emission scenario RCP8.5 results in greater warming compared to RCP4.5.The two models project different precipitation changes,characterized by a general increase in the BCC_CSM1.1,and broader areas with decrease in the RegCM4.0 simulations.
基金supported by the MEP’s Special Funds for Research on Public Welfares (No. 201009001)Chinese Academy of Engineering
文摘This article analyzed the control progress and current status of air quality,identified the major air pollution issues and challenges in future,proposed the long-term air pollution control targets,and suggested the options for better air quality in China.With the continuing growth of economy in the next 10–15 years,China will face a more severe situation of energy consumption,electricity generation and vehicle population leading to increase in multiple pollutant emissions.Controlling regional air pollution especially fine particles and ozone,as well as lowering carbon emissions from fossil fuel consumption will be a big challenge for the country.To protect public health and the eco-system,the ambient air quality in all Chinese cities shall attain the national ambient air quality standards （NAAQS） and ambient air quality guideline values set by the World Health Organization （WHO）.To achieve the air quality targets,the emissions of SO 2,NOx,PM 10,and volatile organic compounds （VOC） should decrease by 60%,40%,50%,and 40%,respectively,on the basis of that in 2005.A comprehensive control policy focusing on multiple pollutants and emission sources at both the local and regional levels was proposed to mitigate the regional air pollution issue in China.The options include development of clean energy resources,promotion of clean and efficient coal use,enhancement of vehicle pollution control,implementation of synchronous control of multiple pollutants including SO 2,NOx,VOC,and PM emissions,joint prevention and control of regional air pollution,and application of climate friendly air pollution control measures.
基金the Basic Research Project of Institute of Geophysics, China Earth-quake Administration (Grant No. DQJB08Z03)
文摘We relocated M8.0 Wenchuan earthquake and 2706 aftershocks with M≥2.0 using double-difference algorithm and obtained relocations of 2553 events. To reduce the influence of lateral variation in crustal and upper mantle velocity structure, we used different velocity models for the east and west side of Longmenshan fault zone. In the relocation process, we added seismic data from portable seismic sta-tions close to the shocks to constrain focal depths. The precisions in E-W, N-S, and U-D directions after relocation are 0.6, 0.7, and 2.5 km respectively. The relocation results show that the aftershock epi-centers of Wenchuan earthquake were distributed in NE-SW direction, with a total length of about 330 km. The aftershocks were concentrated on the west side of the central fault of Longmenshan fault zone, excluding those on the north of Qingchuan, which obviously deviated from the surface fault and passed through Pingwu-Qingchuan fault in the north. The dominant focal depths of the aftershocks are between 5 and 20 km, the average depth is 13.3 km, and the depth of the relocated main shock is 16.0 km. The depth profile reveals that focal depth distribution in some of the areas is characterized by high-angle westward dipping. The rupture mode of the main shock features reverse faulting in the south, with a large strike-slip component in the north.
基金supported by National Basic Research Program of China (Grant No. 2010CB950202)National Natural Science Foundation of China (Grant Nos. 40971056 and 41021091)Fundamental Research Funds for the Central Universities (Grant No. LZUJBKY-2009-82)
文摘This study analyzed the temporal precipitation variations in the arid Central Asia （ACA） and their regional differences during 1930-2009 using monthly gridded precipitation from the Climatic Research Unit （CRU）. Our results showed that the annual precipitation in this westerly circulation dominated arid region is generally increasing during the past 80 years, with an apparent increasing trend （0.7 mm/10 a） in winter. The precipitation variations in ACA also differ regionally, which can be divided into five distinct subregions （Ⅰ West Kazakhstan region, Ⅱ East Kazakhstan region, ⅢCentral Asia Plains region, Ⅳ Kyrgyzstan region, and V Iran Plateau region）. The annual precipitation falls fairly even on all seasons in the two northern subregions （regions Ⅰ and Ⅱ, approximately north of 45°N）, whereas the annual precipitation is falling mainly on winter and spring （accounting for up to 80% of the annual total precipitation） in the three southern subregions. The annual precipitation is increasing on all subregions except the southwestern ACA （subregion Ⅴ） during the past 80 years. A significant increase in precipitation appeared in subregions Ⅰ and Ⅲ. The long-term trends in annual precipitation in all subregions are determined mainly by trends in winter precipitation. Additionally, the precipitation in ACA has significant interannual variations. The 2-3-year cycle is identified in all subregions, while the 5-6-year cycle is also found in the three southern subregions. Besides the inter-annual variations, there were 3-4 episodic precipitation variations in all subregions, with the latest episodic change that started in the mid- to late 1970s. The precipitations in most of the study regions are fast increasing since the late 1970s. Overall, the responses of ACA precipitation to global warming are complicated. The variations of westerly circulation are likely the major factors that influence the precipitation variations in the study region.
