Climate Change over China in the 21st Century as Simulated by BCC_CSM1.1-RegCM4.0

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.     

Interdecadal Change of the Relationship Between the Tropical Indian Ocean Dipole Mode and the Summer Climate Anomaly in China

The interdecadal change of the relationship between the tropical Indian Ocean dipole(IOD) mode and the summer climate anomaly in China is investigated by using monthly precipitation and temperature records at 210 stations in China and the NCEP/NCAR reanalysis data for 1957-2005.The results indicate that along with the interdecadal shift in the large-scale general circulation around the late 1970s,the relationship between the IOD mode and the summer climate anomaly in some regions of China has significantly changed.Before the late 1970s,a developing IOD event is associated with an enhanced East Asian summer monsoon,which tends to decrease summer precipitation and increase summer temperature in South China;while after the late 1970s,it is associated with a weakened East Asian summer monsoon,which tends to increase(decrease) precipitation and decrease(increase) temperature in the south(north) of the Yangtze River.During the next summer,following a positive IOD event,precipitation is increased in most of China before the late 1970s,while it is decreased(increased) south(north) of the Yangtze River after the late 1970s.There is no significant correlation between the IOD and surface air temperature anomaly in most of China in the next summer before the late 1970s;however,the IOD tends to increase the next summer temperature south of the Yellow River after the late 1970s.     

FUTURE CHANGE OF PRECIPITATION EXTREMES OVER THE PEARL RIVER BASIN FROM REGIONAL CLIMATE MODELS

Based on RegCM4, a climate model system, we simulated the distribution of the present climate (1961-1990) and the future climate (2010-2099), under emission scenarios of RCPs over the whole Pearl River Basin. From the climate parameters, a set of mean precipitation, wet day frequency, and mean wet day intensity and several precipitation percentiles are used to assess the expected changes in daily precipitation characteristics for the 21st century. Meanwhile the return values of precipitation intensity with an average return of 5, 10, 20, and 50 years are also used to assess the expected changes in precipitation extremes events in this study. The structure of the change across the precipitation distribution is very coherent between RCP4.5 and RCP8.5. The annual, spring and winter average precipitation decreases while the summer and autumn average precipitation increases. The basic diagnostics of precipitation show that the frequency of precipitation is projected to decrease but the intensity is projected to increase. The wet day percentiles (q90 and q95) also increase, indicating that precipitation extremes intensity will increase in the future. Meanwhile, the 5-year return value tends to increase by 30%-45% in the basins of Liujiang River, Red Water River, Guihe River and Pearl River Delta region, where the 5-year return value of future climate corresponds to the 8- to 10-year return value of the present climate, and the 50-year return value corresponds to the 100-year return value of the present climate over the Pearl River Delta region in the 2080s under RCP8.5, which indicates that the warming environment will give rise to changes in the intensity and frequency of extreme precipitation events.     

Performance of BCC-CSM Models with Different Horizontal Resolutions in Simulating Extreme Climate Events in China

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.     

Changes in Daily Climate Extremes of Observed Temperature and Precipitation in China

Daily precipitation for 1960–2011 and maximum/minimum temperature extremes for 1960–2008 recorded at 549 stations in China are utilized to investigate climate extreme variations.A set of indices is derived and analyzed with a main focus on the trends and variabilities of daily extreme occurrences.Results show significant increases in daily extreme warm temperatures and decreases in daily extreme cold temperatures,defined as the number of days in which daily maximum temperature(Tmax)and daily minimum temperature(Tmin)are greater than the 90th percentile and less than the10th percentile,respectively.Generally,the trend magnitudes are larger in indices derived from Tmin than those from Tmax.Trends of percentile-based precipitation indices show distinct spatial patterns with increases in heavy precipitation events,defined as the top 95th percentile of daily precipitation,in western and northeastern China and in the low reaches of the Yangtze River basin region,and slight decreases in other areas.Light precipitation,defined as the tail of the5th percentile of daily precipitation,however,decreases in most areas.The annual maximum consecutive dry days(CDD)show an increasing trend in southern China and the middle-low reach of the Yellow River basin,while the annual maximum consecutive wet days(CWD)displays a downtrend over most regions except western China.These indices vary significantly with regions and seasons.Overall,occurrences of extreme events in China are more frequent,particularly the night time extreme temperature,and landmasses in China become warmer and wetter.     

Future Precipitation Extremes in China under Climate Change and Their Physical Quantification Based on a Regional Climate Model and CMIP5 Model Simulations

The atmospheric water holding capacity will increase with temperature according to Clausius-Clapeyron scaling and affects precipitation.The rates of change in future precipitation extremes are quantified with changes in surface air temperature.Precipitation extremes in China are determined for the 21st century in six simulations using a regional climate model,RegCM4,and 17 global climate models that participated in CMIP5.First,we assess the performance of the CMIP5 models and RCM runs in their simulation of extreme precipitation for the current period(RF:1982-2001).The CMIP5 models and RCM results can capture the spatial variations of precipitation extremes,as well as those based on observations:OBS and XPP.Precipitation extremes over four subregions in China are predicted to increase in the mid-future(MF:2039-58)and far-future(FF:2079-98)relative to those for the RF period based on both the CMIP5 ensemble mean and RCM ensemble mean.The secular trends in the extremes of the CMIP5 models are predicted to increase from 2008 to 2058,and the RCM results show higher interannual variability relative to that of the CMIP5 models.Then,we quantify the increasing rates of change in precipitation extremes in the MF and FF periods in the subregions of China with the changes in surface air temperature.Finally,based on the water vapor equation,changes in precipitation extremes in China for the MF and FF periods are found to correlate positively with changes in the atmospheric vertical wind multiplied by changes in surface specific humidity(significant at the p<0.1 level).     

Projected Changes in Kppen Climate Types in the 21st Century over China

Future changes in the climate regimes over China as measured by the Kppen climate classification are reported in this paper. The analysis is based on a high-resolution climate change simulation conducted by a regional climate model (the Abdus Salam International Center for Theoretical Physics (ICTP) RegCM3) driven by the global model of Center for Climate System Research (CCSR)/National Institute for Environment Studies (NIES)/Frontier Research Center for Global Change (FRCGC) MIROC3.2_hires (the Model for Interdisciplinary Research on Climate) under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario. Validation of the model performances is presented first. The results show that RegCM3 reproduces the present-day distribution of the Kppen climate types well. Significant changes of the types are found in the future over China, following the simulated warming and precipitation changes. In southern China, the change is characterized by the replacement of subtropical humid (Cr) by subtropical winter-dry (Cw). A pronounced decrease of the cold climate types is found over China, e.g., tundra (Ft) over the Tibetan Plateau and sub-arctic continental (Ec) over northeast China. The changes are usually greater in the end compared with the middle of the 21st century.     

NUMERICAL SIMULATIONS OF EXTREME PRECIPITATION IN EASTERN CHINA UNDER A1B SCENARIO

The regional climate model （RegCM3）, developed by the Abdus Salam International Centre for Theoretical Physics and nested in one-way mode within the latest version of Community Climate System Model from the National Center for Atmospheric Research, is used to conduct a set of experiments to examine its capability of climate simulation for the past 50 years and to explore possible changes in extreme precipitation （EP） in the next 100 years under the A1B scenario. Compared with the observation from the Climate Research Unit at the University of East Anglia and CPC Merged Analysis of Precipitation, RegCM3 reasonably reproduces the spatiotemporal distributions of precipitation and EP in eastern China. Based on the present-day analysis, this study examines the changes in monsoonal precipitation over eastern China in mid- and late-21st century relative to the reference period of 1970-1999. It is found that the precipitation will increase over the middle and lower reaches of the Yangtze River and areas to its north, and decrease over coastal areas to its south, especially in late-21st century. The various indices reflecting extreme events showed that the EP will enhance 10%-15% over the middle and lower reaches of the Yangtze River and areas to its north, and weaken over the areas to its south. The summer monsoon will strengthen and shift northwards under SERS A1B, bringing more water vapor and energy from the Indian Ocean and South China Sea for precipitation and eventually more precipitation over northern China.     

The Extreme Summer Precipitation over East China during 1982–2007 Simulated by the LASG/IAP Regional Climate Model

The extreme summer precipitation over East China during 1982-2007 was simulated using the LASG/IAP regional climate model CREM(the Climate version of a Regional Eta-coordinate Model).The results show that the probability density functions(PDFs) of precipitation intensities are reasonably simulated,except that the PDFs of light and moderate rain are underestimated and that the PDFs of heavy rain are overestimated.The extreme precipitation amount(R95p) and the percent contribution of extreme precipitation to the total precipitation(R95pt) are also reasonably reproduced by the CREM.However,the R95p and R95pt over most of East China are generally overestimated,while the R95p along the coastal area of South China(SC) is underestimated.The bias of R95pt is consistent with the bias of precipitation intensity on wet days(SDII).The interannual variation for R95p anomalies(PC1) is well simulated,but that of R95pt anomalies(PC2) is poorly simulated.The skill of the model in simulating PC1(PC2) increases(decreases) from north to south.The bias of water vapor transport associated with the 95th percentile of summer daily precipitation(WVTr95) explains well the bias of the simulated extreme precipitation.     

Agricultural Land Use Effects on Climate over China as Simulated by a Regional Climate Model

The Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model version 3 (RegCM3) is used to investigate the climate effects of land use change related to agriculture over China. The model is driven by the European Center for Medium-range Weather Forecast 40-yr Re-Analysis (ERA40)data. Two sets of experiments for 15 yr (1987-2001) are conducted, one with the potential vegetation cover and the other the agricultural land use (AG). The results show that the AG effects on temperature are weak over northern China while in southern China a significant cooling is found in both winter (December-January-February) and summer (June-July-August). The mean cooling in the sub-regions of South China (SC) in winter and the sub-regions of Southeast (SE) China in summer are found to be the greatest,up to 0.5℃ and 0.8℃, respectively. In general, the change of AG leads to a decrease of annual mean temperature by 0.5-1℃ in southern China. Slight change of precipitation in western China and a decrease of precipitation in eastern China are simulated in winter, with the maximum reduction reaching -7.5% over SE. A general decrease of precipitation over northern China and an increase over southern China are simulated in summer,in particular over SE where the increase of precipitation can be up to 7.3%. The AG effects on temperature and precipitation show strong interannual variability. Comparison of the climate effects between AG and the present-day land use (LU) is also performed. In southern China, the ratio of temperature (precipitation)changes caused by AG and LU is greater than (closer to) the ratio of the number of grid cells with changed vegetation cover due to AG and LU variations.     

我国短期气候预测业务系统

中国第一代短期气候监测、预测、评价和服务业务系统主要由6个部分组成：数据库、动力气候模式系统、气候监测诊断系统、短期气候预测系统、气候影响评价系统与气候应用服务系统。在建立短期气候业务系统过程中，主要获得了三方面的成果：第一，揭示出影响中国气候异常的最强气候信号是厄尔尼诺事件、高原积雪和季风；第二，发展并建立了复杂的全球与区域动力气候模式预测系统，该系统包括T63L16全球大气环流模式、高分辨率区域气候模式、T63L30全球海洋模式和海冰模式、太平洋和印度洋高分辨率海洋模式和厄尔尼诺预测模式；第三，在高性能计算机和网络的支持下建立了完整的业务应用系统，不仅可提供短期气候预测信息，而且可以快速、客观、准确地给出气候变化对水资源、农业、林业、交通、电力、重大工程等国民经济重要部门和关键地区的影响，及时为决策部门提供决策服务。1998年开始应用以来，国家和大区两级整体预报水平比“九五”以前20年平均提高了6％～10％。但对区域性强洪涝事件的预报能力偏低，尚需进一步提高。     

气候动力学与气候预测理论的研究

主要概述了中国科学院大气物理研究所近些年来在气候动力学与气候预测理论研究领域的若干重要研究进展.通过对气候系统变化多尺度特征及其动力学的分析和研究,提出了一系列气候系统动力学理论,并在此基础上提出了适合于我国季风气候特点的气候预测理论和方法,在国际上率先开展了跨季度数值气候预测,进一步建立了先进、完善的短期数值气候预测系统,并应用于我国夏季旱涝预测业务.这些工作既带有极大的基础性意义,同时也具有巨大的应用价值,为我国大气科学及气候科学乃至环境科学的研究提供了重要工具.     

干旱半干旱区气候变化研究综述

从干旱半干旱区气候的时空变化特征、陆气相互作用的观测试验以及气候变化的动力学机制等几个方面系统总结了近年来国内外干旱半干旱区气候变化的最新研究进展,指出目前干旱半干旱区气候变化研究以特定区域研究为主,缺乏对全球不同区域干旱半干旱区气候变化时空关联的系统性归纳研究,且野外观测试验持续时间较短,这在很大程度上限制了对干旱半干旱区气候变化机理的认识和陆面过程模式的发展。针对这些问题,从资料获取、资料分析及数值模拟3个方面提出未来干旱半干旱区气候变化研究的主要方向。     

气候观测系统及其相关的关键问题

地球系统中的大气圈、水圈、冰雪圈、岩石圈和生物圈构成了气候系统, 气候系统中不同圈层之间的相互作用决定了气候的自然变化。由于人类活动的日益加剧, 对气候系统已经产生了显著影响。气候的自然变化和人类活动导致的气候变化对社会经济的发展以及人民生活的影响日益加大, 并涉及到国家安全、环境外交和可持续发展等一系列重大问题。要认识气候变化及其强迫因素、预测未来气候变化, 最基础的工作是建立针对气候目的涉及到气候系统五大圈层的综合气候观测系统, 以获取所需的高质量资料和相关产品, 提供气候系统变化的详细信息。该文回顾了气候观测系统设计在中国的发展以及中国气象科学研究院在组织设计中国气候观测系统中的作用, 并指出了在建立我国气候观测系统中存在的一些需要改进的方面。在对气候观测系统进行分析的基础上, 指出了与建立气候观测系统相关的10个方面的关键问题, 这些问题包括:气候观测系统的科学需求、气候观测系统的代表性、全面性、规范性、对气候预测和预估及模式发展的支撑性、多学科应用性、社会经济性、资料开放共享性以及气候系统资料的同化再分析和历史资料的抢救。     

Reducing Uncertainties in Climate Projections with Emergent Constraints:Concepts,Examples and Prospects

Models disagree on a significant number of responses to climate change,such as climate feedback,regional changes,or the strength of equilibrium climate sensitivity.Emergent constraints aim to reduce these uncertainties by finding links between the inter-model spread in an observable predictor and climate projections.In this paper,the concepts underlying this framework are recalled with an emphasis on the statistical inference used for narrowing uncertainties,and a review of emergent constraints found in the last two decades.Potential links between highlighted predictors are explored,especially those targeting uncertainty reductions in climate sensitivity,cloud feedback,and changes of the hydrological cycle.Yet the disagreement across emergent constraints suggests that the spread in climate sensitivity can not be significantly narrowed.This calls for weighting the realism of emergent constraints by quantifying the level of physical understanding explaining the relationship.This would also permit more efficient model evaluation and better targeted model development.In the context of the upcoming CMIP6 model intercomparison a growing number of new predictors and uncertainty reductions is expected,which call for robust statistical inferences that allow cross-validation of more likely estimates.     

Past and Future Changes in the Climate of Hong Kong

Over the years, the Hong Kong Observatory has carried out scientific studies to evaluate the observed climate trends and project the future climate in Hong Kong. Analysis of the meteorological observations at the observatory's headquarters in Tsim Sha Tsui since 1885 reveals that the temperature rise in Hong Kong during the past 124 years is in accord with the global rising trend. The accelerated rising trend in the mean temperature in last few decades may be attributed to the anthropogenic influences, especially urbanization. A similar increasing trend is also observed for rainfall. Other observations such as increasing cloud amount and decreasing total global solar radiation are all consistent with the global trend. Studies of past occurrences of extreme temperature and rainfall have also been carried out. The results indicate that cold episodes have become rarer while very hot days and heavy rain events are becoming more frequent. The observatory also makes use of the data from the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) and employs statistical downscaling techniques to carry out projections of temperature and precipitation in the 21st century. It is found that the rise in temperature in Hong Kong will be slightly higher than the global mean in the 21st century. The annual rainfall in Hong Kong is also expected to rise by the end of the 21st century, so is its year-to-year variability.     

云南气候特征与主要经济作物种植适宜性的关系

基于云南省、贵州省和广西壮族自治区共163个站点气候资料和主要经济作物产地分布数据,应用作物生态学和农业气象学原理,分析云南气候特征与经济作物种植的气候适宜性关系。结果表明,受季风气候、高原山地气候、低纬气候的影响,云南干湿季节分明、夏季气温偏低、春秋季长、气温日较差大、干季日照较多,具有气候区域性和层次性差异特点,由此云南各气候带的经济作物种植适宜性也不同,其中,低纬高原气候最适宜云南烤烟和滇中花卉产业发展,低纬高原南亚热带季风气候区的滇西南适宜种植喜湿润、要求强光少的南亚热带深根类作物,高原山地气候叠加季风气候带则适宜发展多种(类)经济作物,然而高原气候和季风气候也给云南经济作物种植带来夏秋光热欠足、冬春干旱和短时段低温冷害的不利影响。     

贵州省旅游气候品牌效应初探

旅游业是贵州经济发展的重要支柱产业。气候资源作为不可或缺的一种旅游资源,既造就了贵州多彩多姿的自然风光和人文景观,又以“冬无严寒、夏无酷暑”的气候优势,极大地增加了贵州旅游的吸引力,尤其是在“气象+旅游”模式下,形成了由避暑旅游辐射开来的全省生态旅游“集团化”品牌,对贵州地方经济、社会发展、生态建设和乡村振兴产生极大的推动作用。文章在分析贵州气候优势条件的基础上,研究探讨了旅游气候品牌效应,提出在继续深挖夏季气候优势,持续打造避暑旅游品牌的前提下,应根据贵州立体气候特征及贵州独具特色的喀斯特地域地貌,深入发掘贵州冬季避寒、康养、低纬度地区冬季赏雪观景等气候旅游资源,为打造贵州全域旅游、全时旅游品牌提供参考。     

中国柯本气候分类

利用中国734个气象站点1957-2016年的气温和降水量数据,结合柯本气候分类,采用薄板样条插值法,研究中国柯本气候分类的时空分布及变化特征。结果表明：1957-2016年中国包括5个气候带,其中赤道气候带（0.17%）包括热带季风和热带疏林草原气候,干旱气候带（41.38%）包括冷性沙漠和冷性草原气候,暖温气候带（25.53%）包括热夏冬干暖温、温夏冬干暖温、热夏常湿暖温以及温夏常湿暖温气候类型,冷温气候带（28.44%）包括热夏冬干冷温、温夏冬干冷温、冷夏冬干冷温、热夏常湿冷温、温夏常湿冷温以及冷夏常湿冷温气候类型,极地气候带（4.48%）仅有苔原气候。在此60 a,气候变化主要体现在冷温气候带向干燥气候带和暖温气候带的转移,以及冷温气候带中冷夏向温夏的转移和温夏向热夏的转移。     

黑龙江省气候变暖对极端天气气候事件的影响

黑龙江省1980年以来气候变暖已成为事实，气候变暖导致天气气候极端事件的发生，主要表现在：①大雨暴雨次数增加；②30℃以上极端最高气温平均日数下降；③-30℃以下极端最低气温平均日数明显减少；④初霜日平均后延2～5天；⑤终霜日，北部中部提前3～5天而南部延长；⑥夏季低温次数明显减少，北部减少多于南部；⑦大旱年次数增多，大涝次数北少南多，西南部地区为旱涝敏感区。