温室效应引起的中国区域气候变化的数值模拟Ⅰ:模式对中国气候模拟能力的检验

使用RegCM2区域气候模式单向嵌套澳大利亚CSIRO R21L9全球海-气耦合模式,进行了CO2加倍对中国区域气候变化影响的数值试验研究,分析了控制试验(1×CO2)即模式对中国当代气候的模拟情况.首先给出了全球模式控制试验在中国地区的结果,分析表明它对中国区域的地面气温和降水具有一定的模拟能力,其结果可以用来制作驱动区域气候模式的初始场和侧边界.对RegCM2 5 a时间长度控制试验积分结果的分析与检验表明,区域气候模式由于具有较高的分辨率和较完善的物理过程,它对中国区域地面气温和降水的模拟效果较全球模式有了较大提高,如它模拟的各月气温与实况的相关系数全年12个月的平均由全球模式的0.83提高到0.92,降水由0.48提高到0.65.     

用区域气候模式模拟人为硫酸盐气溶胶在气候变化中的作用

使用新版RegCM2区域气候模式，单向嵌套澳大利亚CSIROR21L9全球海-气耦合模式，在C02加倍情况下引人人为硫酸盐气溶胶直接气候效应，进行了其对中国气候变化影响的试验。结果表明，硫酸盐气溶胶的直接气候效应，对地面气温为降温作用，其中在冬半年和在南方更明显；对降水的影响为全国各月平均降水将以减少为主，年平均降水变化的基本特点为在中国东部以减少为主，西部以增加为主。但无论温度还是降水变化的数值都很小。     

区域气候模式对温室效应引起的中国地区气候变化的数值模拟

利用基于 ＲｅｇＣＭ２的区域气候模式并单向嵌套澳大利亚 ＣＳＩＲＯ Ｒ２１Ｌ９全球海－气耦合模式，进行了温室气体二氧化碳浓度倍增对中国气候变化影响的数值试验研究。控制试验结果表明：区域模式由于具有较高的分辨率，因而对中国区域地面气温和降水的模拟效果较全球模式有了较大提高；模式对 ２×ＣＯ２敏感性试验结果表明了在 ＣＯ２浓度倍增情况下，由于温室效应，中国区域的地面气温将有明显升高，降水也将呈增加趋势。     

土地利用变化对我国区域气候影响的数值试验

使用RegCM2区域气候模式单向嵌套澳大利亚CSIRO R21L9全球海-气耦合模式,通过将中国区域植被覆盖由理想状况改变为实际状况的数值试验对比分析,探讨了当代中国土地利用变化对中国区域气候的影响,并对结果进行了统计显著性检验。研究表明,土地利用的变化,会导致我国西北等地区年平均降水减少,导致年平均气温在内陆部分地区升高和在沿海个别地区降低,引起许多地方夏季日平均最高气温升高,而冬季日平均最低气温则在我国东部部分地区降低的同时在西北地区升高,土壤湿度的变化表现为大范围的降低。研究同时表明,相同的土地变化在不同的地理环境下引起的气候要素变化有一定的不一致性。     

MODELING THE EFFECTS OF ANTHROPOGENIC SULFATE IN CLIMATE CHANGE BY USING A REGIONAL CLIMATE MODEL

1 INTRODUCTION Being an important composition of the atmosphere, aerosol attracts increasing attention from the scientific community in recent years, together with the radiative forcing it causes and effects it imposes on the climate system. The anthropogenic aerosol affects the climate both directly and indirectly. The climate is directly affected when solar shortwave radiation is scattered and absorbed in what is known as the 搖mbrella effect? which can be dated back to as early as mor…     

温室效应对我国东部地区气候影响的高分辨率数值试验

使用RegCM3区域气候模式,单向嵌套NASA/NCAR 的全球环流模式FvGCM的输出结果,对中国东部地区进行了在实际温室气体浓度下当代1961~1990年和在IPCC A2温室气体排放情景下21世纪末期2071~2100年各30年时间长度,水平分辨率为20 km的气候变化模拟试验。首先分析全球和区域模式对中国东部地区当代气候的模拟情况,结果表明全球模式对中国东部地区气温的总体分布型模拟较好,但存在冷偏差,区域模式在对这个冷偏差有所纠正的同时,提供了气温地理分布更详细的信息。全球模式模拟的年降水中心位于长江流域,与观测差别较大,区域模式对此同样也有改进,降水高值区主要位于区域南部,并表现出较强的地形强迫特征。区域模式的模拟结果还表明,至21世纪末期,在温室效应作用下,中国东部的气温将明显升高,年平均气温的升高值在2.7~4.0℃之间,其中北部升温大于南部,冬季升温大于夏季。冬季升温表现出明显的随纬度增加而增加的分布型。模拟区域内年平均降水将增加,增加值一般在10%以上,部分地区达到30%。降水增加在夏季较明显,区域内以普遍增加为主,冬季降水自山东半岛至湖南地区将减少,其他地区增加。此外,对夏季高温日数和冬季低温日数及年平均大雨日数的变化也进行了分析。     

Regional Nested Model Simulations of Present Day and 2 × CO2 Climate over the Central Plains of the U.S.

A nested regional climate model is used to generate a scenario of climate change over the MINK region (Missouri, Iowa, Nebraska, Kansas) due to doubling of carbon dioxide concentration (2 × CO₂) for use in agricultural impact assessment studies. Five-year long present day (control) and 2 × CO₂ simulations are completed at a horizontal grid point spacing of 50 km. Monthly and seasonal precipitation and surface air temperature over the MINK region are reproduced well by the model in the control run, except for an underestimation of both variables during the spring months. The performance of the nested model in the control run is greatly improved compared to a similar experiment performed with a previous version of the nested modeling system by Giorgi et al. (1994). The nested model generally improves the simulation of spatial precipitation patterns compared to the driving general circulation model (GCM), especially during the summer. Seasonal surface warming of 4 to 6 K and seasonal precipitation increases of 6 to 24% are simulated in 2 × CO₂ conditions. The control run temperature biases are smaller than the simulated changes in all seasons, while the precipitation biases are of the same order of magnitude as the simulated changes. Although the large scale patterns of change in the driving GCM and nested RegCM model are similar, significant differences between the models, and substantial spatial variability, occur within the MINK region.     

区域气候模式对我国中、东部夏季气候的数值模拟

利用高分辨率的区域气候模式RegCM3(ICTP,2004年)对1994、1997、1998年我国夏季(6～8月)气候进行了数值模拟试验,并对比分析了不同积云对流方案对降水场模拟结果的影响。结果表明:该模式能够较真实地描述出我国夏季温度场的主要高、低温中心及月际变化,但模拟的气温场偏低;选择不同的积云对流方案对降水的模拟结果影响很大,采用Grell积云对流方案模拟出的我国夏季降水场最接近观测场,较好地模拟出我国东部地区夏季主要雨带的大致位置及变化,但雨带的位置偏南、中心降水量值偏大;500 hPa位势高度场的模拟结果和实际观测场较为一致,但西风带的位置偏南,相应地副热带高压588位势什米线位置较观测场向东南偏移。     

水文模式DHSVM与区域气候模式RegCM2/China嵌套模拟试验

本研究在改进水文 -土壤 -植被模式DHSVM ,用气候观测资料驱动DHSVM进行模拟试验的基础上 ,建立了区域气候模式RegCM2 /China与水文模式DHSVM的嵌套系统 ,将区域气候模式对中国和东亚地区控制试验 (目前气候情景 )和敏感性试验 (未来 2×CO2 气候情景 )结果用双线性插值方法降尺度 (downscaling)到滦河、桑干河流域的 8个气象站点 ,然后再用数字高程模式DEM插值到DHSVM的细网格点 ,驱动水文模式进行嵌套模拟试验。试验结果表明 ,滦河、桑干河流域在未来大气中CO2 浓度加倍情况下 ,地面气温呈一致的增加趋势 ,年平均气温增加2 .8℃ ;两流域未来降水也呈增加趋势 ,滦河、桑干河流域年降水量分别增加 6mm和 4 6mm ;两流域未来蒸发量有所增加 ,年均蒸发量增加 2 9mm ;未来滦河流域年径流深减少 2 7mm ,流量减少 14 .72× 10 8m3 ,桑干河流域径流深增加 2 6mm ,流量增加 12 .2 2× 10 8m3 ,两流域合计 ,流量减少 2 .5× 10 8m3 ;未来滦河、桑干河流域径流深趋向一致 ,分别为 74和 71mm ,约为全国目前平均径流深 2 84mm的 1/ 4。可见 ,两流域未来总体上仍呈现暖干化趋势。本研究发展的嵌套模式系统具有一定的预测能力 ,而且通过参数移植 ,可应用于中国其他流域     

Climate Scenarios for the Southeastern U.S. Based on GCM and Regional Model Simulations

We analyze the control runs and 2 × CO₂ projections (5-yearlengths) of the CSIRO Mk 2 GCM and the RegCM2 regional climate model, which was nested in the CSIRO GCM, over the Southeastern U.S.; and we present the development of climate scenarios for use in an integrated assessment of agriculture. The RegCM exhibits smaller biases in both maximum and minimum temperature compared to the CSIRO. Domain average precipitation biases are generally negative and relatively small in winter, spring, and fall, but both models produce large positive biases in summer, that of the RegCM being the larger. Spatial pattern correlations of the model control runs and observations show that the RegCM reproduces better than the CSIRO the spatial patterns of precipitation, minimum and maximum temperature in all seasons. Under climate change conditions, the most salient feature from the point of view of scenarios for agriculture is the large decreases in summer precipitation, about 20% in the CSIRO and 30% in the RegCM. Increases in springprecipitation are found in both models, about 35% in the CSIRO and 25% in theRegCM. Precipitation decreases of about 20% dominate in winter in the CSIRO,while a more complex pattern of increases and decreases is exhibited by the regional model. Temperature increases by 3 to 5 °C in the CSIRO, the higher values dominating in winter and spring. In the RegCM, temperature increases are much more spatially and temporally variable, ranging from 1 to 7 °C acrossall months and grids. In summer large increases (up to 7 °C) in maximum temperature are found in the northeastern part of the domain where maximum drying occurs.     

SIMULATION OF PRESENT CLIMATE OVER EAST ASIA BY A REGIONAL CLIMATE MODEL

A 15-year simulation of climate over East Asia is conducted with the latest version of a regional climate model RegCM3 nested in one-way mode to the ERA40 Re-analysis data. The performance of themodel in simulating present climate over East Asia and China is investigated. Results show that RegCM3 can reproduce well the atmospheric circulation over East Asia. The simulation of the main distribution patterns of surface air temperature and precipitation over China and their seasonal cycle/evolution, are basically agree with that of the observation. Meanwhile a general cold bias is found in the simulation. AS for the precipitation, the model tends to overestimate the precipitation in northern China while underestimate it in southern China, particularly in winter. In general, the model has better performance in simulating temperature than precipitation.     

RegCM3对东亚环流和中国气候模拟能力的检验

使用RegCM3区域气候模式,嵌套ERA40再分析资料,对东亚地区进行了15年（1987～2001年）时间长度的数值积分试验,分析了模式对东亚平均环流及中国地区气温和降水的模拟。结果表明,模式对东亚平均环流的特征和中国地区降水、地面气温的年、季地理分布和季节变化特征均具有一定的模拟能力,对气温和降水年际变率的模拟也较好。此外模式模拟在测站稀少地区,可以提供局地如降水分布更可靠的信息。模式对气温的模拟存在1-3℃的系统性冷偏差;对中国地区降水地理分布的模拟也存在一定偏差,如对年平均降水的模拟中,降水最大值位置与观测有一定差距,特别是对冬季降水中心的模拟存在较大偏差。模式模拟的夏季降水,在中国北方地区总体偏大100-200 mm,南方总体偏小100-200 mm。模式对地面气温的模拟效果好于降水。     

Comparison of Agricultural Impacts of Climate Change Calculated from High and Low Resolution Climate Change Scenarios: Part II. Accounting for Adaptation and CO2 Direct Effects

We assert that the simulation of fine-scale crop growth processes and agronomic adaptive management using coarse-scale climate change scenarios lower confidence in regional estimates of agronomic adaptive potential. Specifically, we ask: 1) are simulated yield responses tolow-resolution climate change, after adaptation (without and with increased atmospheric CO₂), significantly different from simulated yield responses tohigh-resolution climate change, after adaptation (without and with increased atmospheric CO₂)? and 2) does the scale of the soils information, in addition to the scale of the climate change information, affect yields after adaptation? Equilibrium (1 × CO₂ versus 2 × CO₂)climate changes are simulated at two different spatial resolutions in the Great Plains using the CSIRO general circulation model (low resolution) and the National Center for Atmospheric Research (NCAR) RegCM2 regional climate model (high resolution). The EPIC crop model is used to simulate the effects of these climate changes; adaptations in EPIC include earlier planting and switch to longer-season cultivars. Adapted yields (without and with additional carbon dioxide) are compared at the different spatial resolutions. Our findings with respect to question 1 suggest adaptation is more effective in most cases when simulated with a higher resolution climate change than its more generalized low resolution equivalent. We are not persuaded that the use of high resolution climate change information provides insights into the direct effects of higher atmospheric CO₂ levels on crops beyond what can be obtained with low resolution information. However, this last finding may be partly an artifact of the agriculturally benign CSIRO and RegCM2 climate changes. With respect to question 2, we found that high resolution details of soil characteristics are particularly important to include in adaptation simulations in regions typified by soils with poor water holding capacity.     

高分辨嵌套区域气候模式对我国中、东部地区夏季气候的数值模拟

利用引进的ＮＣＡＲ＿ＲｅｇＣＭ２模式在较高分辨率情况下,对我国东部地区夏季气候状况进行了数值模拟。结果表明,模式能够较真实地再现我国东部 地区夏季气候的基本状况。模拟的海平面气压场、５００ｈＰａ高度场、地表温度场以及对流层高、低层风场等的分布形式,都与实测场比较一致。并且较好地模拟出了７月中旬副热带的北跳。模式模拟的夏季降水场分布形式也与观测结果一致。高、低值中心等对应较好,不足之处是模拟中心值测     

Simulation of paleoclimate over East Asia at 6 ka BP and 21 ka BP by a regional climate model

Using a regional climate model with detailed land surface processes (RegCM2), East Asian monsoon climates at 6 ka BP and 21 ka BP are simulated by prescribing vegetation and employing paleovegetation respectively in order to examine land surface effects on East Asian climate system and the potential mechanisms for climate change. The RegCM2 with a 120 × 120 km² resolution has simulated the enlargement of the seasonal cycle of insolation, the temperature rising the whole year, and the reduction of perpetual snow in high latitudes at 6 ka BP. The simulation shows the East Asian summer monsoon strengthening, precipitation and P–E increasing, and the monsoon rain belt shifting westwards and northwards. Effect of paleovegetation included in the modeling reduced surface albedo and caused an increase in the winter temperature, which led to weakening of the winter continental cold anticyclone over China. The results make the seasonal characteristics of simulated temperature changes in better agreement with the geological records, and are an improvement over previous simulations of Paleoclimate Modeling Intercomparison Project (PMIP). The RegCM2 simulated the 21 ka BP climate with lowered temperature throughout the year, and with precipitation reduced in most areas of East Asia (but increased in both the Tibetan Plateau and Central Asia). Low temperature over East Asia led to the strengthening of the East Asian winter monsoon and the shrinking of the summer monsoon. The effect of paleovegetation included in the experiment has enlarged the glacial climate influence in East Asia, which is closer to geological data than the PMIP simulations directly driven by insolation, glaciation and low CO₂ concentration.     

THE NUMERICAL SIMULATION OF THE ICE AGE CLIMATE

Using the lAP two-level general circulation model,the ice age July climate was simulated through the surface conditions of 18 000 years before present assembled by the CLIMAP Project.Comparing with the present July simulation results,the ice age atmosphere is found to have a substantially lower temperature,precipitation,and cloudiness,higher sea-level pressure,especially in the high latitude land region of the Northern Hemisphere and Antarctica.When the CO₂ content is set as the modern value the climatic response is very small,which shows that the problems of CO₂ sensitivity should be studied by means of coupled models.It is also pointed out that there are some common characteristics between CO2-induced climatic changes and the ice age surface condition-induced climatic changes,which may give us some insight into how climate responds to external forcings.     

用 IAP／LASG GOALS模式模拟CO2增加引起的东亚地区气候变化

Two simulations, one for the control run and another for the perturbation run, with a global coupled ocean-atmosphere-land system model (IAP / LASG GOALS version 4) have been carried out to study the global warming, with much detailed emphasis on East Asia. Results indicate that there is no climate drift in the control run and at the time of CO2 doubling the global temperature increases about 1.65℃. The GOALS model is able to simulate the observed spatial distribution and annual cycles of temperature and precipitation for East Asia quite well. But, in general, the model underestimates temperature and overestimates rainfall amount for regional annual average. For the climate change in East Asia, the temperature and precipitation in East Asia increase 2. l℃ and 5% respectively, and the maximum warming occurs at middle-latitude continent and the maximum precipitation increase occurs around 25°N with reduced precipitation in the tropical western Pacific.     

华北地区未来气候变化的高分辨率数值模拟

使用20km高水平分辨率的区域气候模式RegCM3,单向嵌套FvGCM/CCM3全球模式,进行了中国区域气候变化的数值模拟试验,分析华北地区夏半年4-9月的气温、降水和高温、干旱事件的变化。模式积分时间分为两个时段,分别为当代的1961-1990年和在IPCC SRES A2温室气体排放情景下的21世纪末2071-2100年。模式检验结果表明:在大部分月份,区域模式对当代气候的模拟都较全球模式更好。两个模式模拟的未来气温和降水变化,在空间分布型和量级上都有一定不同,如区域模式的升温更高,降水出现大范围减少等。此外,使用日最高气温不低于35℃的日数(D_(T35))和考虑了湿度因素的炎热指数(I_(H))不低于35℃的日数(D_(H135)),分析了区域模式模拟的未来高温事件变化,结果表明:未来华北地区D_(T35)和平原地区D_(H135)均有较大增加。未来华北地区的连续干旱日数(CDD)将增加,依照UNEP(United Nations Environment Programme)干旱指数(A_(U))给出的气候湿润区将有较大幅度减少,而半湿润半干旱区和半干旱区面积将增加。     

PROJECTIONS OF CLIMATE CHANGE FOR THE CZECH REPUBLIC

The paper deals with a selection of the climatological baseline, GCM validity and construction of the climate change scenarios for an impact assessment in the Czech territory. The period of 1961–1990 has been selected as the climatological baseline. The corresponding database includes more than 50 monthly mean temperature and precipitation series, and 16 time series of daily meteorological data that contain also the solar radiation data. The 1× CO₂ outputs produced by four GCMs, provided by the CSMT (GISS, GFD30, GFD01, and CCCM), were compared with observed temperature and precipitation conditions in western and central Europe with a particular attention devoted to the Czech territory. The GCM ability to simulate annual cycles of temperature, precipitation and radiation was thoroughly examined. The GISS and CCCM were selected as a basis for constructing climate change scenarios as they simulated reasonably the observed patterns. According to the GISS variant, 2× CO₂ climate assumes a higher winter and lower summer warming, and an increase in annual precipitation amounts. A dangerous combination of the summer temperature increase and declining precipitation amounts is a specific feature of the CCCM scenario. An incremental scenario for temperature and precipitation is based on the combination of prescribed changes in both annual means and annual courses.     

东亚区域极端气候事件变化的数值模拟试验

使用ResCM2区域气候模式,嵌套澳大利亚CSIRO R21L9全球海气耦合模式,进行了温室效应（二氧化碳加倍）对东亚（主要是中国区域）极端气候事件影响的数值试验。控制试验的结果表明,区域模式能够较好地模拟中国区域的极端气候事件。对温室效应引起的它们的变化进行了信度检验,分析结果表明,温室效应将引起日最高和最低气温增加,日较差减小;使得高温天气增多,低温日数减少。降水日数和大雨日数在一些地区将增加。同时还会引起影响中国的台风活动的变化。