中国西部退耕还林(草)和沙漠化土地绿化的区域性气候效应

中国正在实施的西部大开发必将导致较大规模的土地利用和地表覆盖(LULC)变化,其中最重要的两类LULC变化是退耕还林(草)和沙漠化土地绿化工程。利用最新的全球地表特征资料数据库(GLCCD)识别以上两项生态建设工程的实施规模与范围,并以此更新了目前比较流行的区域气候模式的下边界条件,利用修正了的区域气候模式研究上述大规模LULC变化可能对中国区域性气候造成的影响。使用的卫星资源数据库是由美国地质测绘局(USGS)和Nebraska-Lincoln大学牵头,根据NOAA卫星的AVHRR资料、USGS掌握的高分辨率数字化地图,以及生态区划和植被分布等资料组建的。     

Effects of Updated RegCM4 Land Use Data on Near-Surface Temperature Simulation in China

Biogeophysical effects of land use and land cover (LULC) changes play a significant role in modulating climate on various spatial scales. In this study, a set of recent LULC products with a spatial resolution of 500 m was developed in China for update in RegCM4 (regional climate model version 4). Two sets of comparative numerical experiments were conducted to study the effects of LULC changes on near-surface temperature simulation. The results show that after LULC changes, areas of crops and mixed woodlands as well as urban areas increase over entire China, accompanied with greatly expanded mixed farming and forests/field mosaics in southern China, and reduced areas of 1) irrigated crops and short grasses in northern China and the Tibetan Plateau, and 2) semi-desert and desert in northwestern China. Improvements in the LULC data clearly result in more accurate simulations of the near-surface temperature. Specifically, increasing latent heat and longwave albedo due to enhanced LULC in certain areas lead to reduction in land surface temperature (LST), while changes in shortwave albedo and sensible heat also exert a great influence on the LST. Overall, these parameter adjustments reduce the biases in near-surface temperature simulation.     

北方土地利用变化对中国夏季气候可能影响的敏感性试验

为考察中国北方地区当代土地利用变化对中国夏季气候的可能影响,以区域气候模式RegCM3为模拟工具,利用1992年和1999年的土地利用资料,进行了中国地区植被覆盖变化的敏感性试验。结果表明,中国北方地区土地利用/植被覆盖的改变,将通过影响大气环流和改变陆地—大气或植被—大气之间的能量平衡状态等,对降水和气温等产生较大影响。     

Simulations of Water Resource Changes in Eastern and Central China in the Past 130 Years by a Regional Climate Model

Anthropogenic influences on regional climate and water resources over East Asia are simulated by using a regional model nested to a global model. The changes of land use/land cover (LULC) and CO₂ concentration are considered. The results show that variations of LULC and CO₂ concentration during the past 130 years caused a warming trend in many regions of East Asia. The most remarkable temperature increase occurred in Inner Mongolia, Northeast and North China, whereas temperature decreased in Gansu Province and north of Sichuan Province. LULC and CO₂ changes over the past 130 years resulted in a decreasing trend of precipitation in the Huaihe River valley, Shandong Byland, and Yunnan-Guizhou Plateau, but precipitation increased along the middle reaches of the Yangtze River, the middle reaches of the Yellow River, and parts of South China. This pattern of precipitation change with changes in surface evapotranspiration may have caused a more severe drought in the lower reaches of the Yellow River and the Huaihe River valley. The drought trend, however, weakened in the mid and upper reaches of the Yellow River valley, and the Yangtze River valley floods were increasing. In addition, changes in LULC and CO₂ concentration during the past 130 years led to adjustments in the East Asian monsoon circulation, which further affected water vapor transport and budget, making North China warm and dry, the Sichuan basin cold and wet, and East China warm and wet.     

Land use and land cover tools for climate adaptation

Land use and land cover interact with atmospheric conditions to determine current climate conditions, as well, as the impact of climate change and environmental variability on ecological systems. Such interactions are ubiquitous, yet changes in LULC are generally made without regard to their biophysical implications. This review considers the potential for LULC to compound, confound, or even contradict changes expected from climate change alone. These properties give LULC the potential to be used as powerful tools capable of modifying local climate and contributing significantly to the net impact of climate change. Management practices based modifications of LULC patterns and processes could be applied strategically to increase the resilience of vulnerable ecological systems and facilitate climate adaptation. These interventions build on the traditional competencies of land management and land protection organizations and suggest that these institutions have a central role in determining the ecological impact of climate change and the development of strategies for adaptation. The practical limits to the use of LULC-based tools also suggest important inflection points between manageable and dangerous levels of climate change.     

陆面过程模式LPM-ZD及其对我国中东部地区陆面特征的模拟

该文利用陆面过程模式ＬＰＭ┐ＺＤ和一套观测分析资料对我国中东部地区的陆面特征进行了模拟研究．模拟结果表明：模式ＬＰＭ┐ＺＤ比较好地模拟了该区域内不同类型植被和土壤的温、湿变量以及陆气间通量交换的日变化特征；能够合理地模拟我国中东部区域的陆面过程特点分布，很好地反映了我国南北方区域气候特点的差异和我国夏季风气候特点     

中国周边海域海面温度日变化对区域气候的影响

利用区域气候模式,分别以逐时海面温度(sea surface temperature, SST)数据及逐日SST数据作为模式的海表温度进行强迫,开展了1991～2010年共计20年的数值模拟,探讨SST日变化对中国区域气候变化的影响。对比结果表明,两组试验均能合理地再现中国区域气候的主要气候态特征。同时发现,两组试验模拟的气候特征在我国沿海区域以及近海洋面上存在明显差异:考虑SST日变化之后,2 m气温和感热通量差异呈现夏季(冬季)升高(降低)为主的趋势;潜热通量则与之相反;低层风场差异在夏季以海洋吹向大陆的东南风为主,冬季则以陆面吹向海洋的西北风差异为主;另外,水汽输送差异呈气旋式(反气旋式)时,降水出现正差异(负差异)。SST日变化对上述气候因子的影响在夏季更为显著。     

Soil temperature response in Korea to a changing climate using a land surface model

The land surface processes play an important role in weather and climate systems through its regulation of radiation, heat, water and momentum fluxes. Soil temperature (ST) is one of the most important parameters in the land surface processes; however, there are few extensive measurements of ST with a long time series in the world. According to the CLImatology of Parameters at the Surface (CLIPS) methodology, the output of a trusted Soil-Vegetation- Atmosphere Transfer (SVAT) scheme can be utilized instead of observations to investigate the regional climate of interest. In this study, ST in South Korea is estimated in a view of future climate using the output from a trusted SVAT scheme — the University of TOrino model of land Process Interaction with Atmosphere (UTOPIA), which is driven by a regional climate model. Here characteristic changes in ST are analyzed under the IPCC A2 future climate for 2046-2055 and 2091-2100, and are compared with those under the reference climate for 1996-2005. The UTOPIA results were validated using the observed ST in the reference climate, and the model proved to produce reasonable ST in South Korea. The UTOPIA simulations indicate that ST increases due to environmental change, especially in air temperature (AT), in the future climate. The increment of ST is proportional to that of AT except for winter. In wintertime, the ST variations are different from region to region mainly due to variations in snow cover, which keeps ST from significant changes by the climate change.     

中国农田下垫面变化对气候影响的模拟研究

使用同期的美国国家环境预报中心/能源部(NCEP/DOE)再分析资料驱动区域气候耦合模式AVIM-RIEMS2.0,从遥感卫星图像资料中获取3期中国土地利用/覆盖数据中的农田植被类型,将其分别引入到AVIM-RIEMS2.0模式进行积分,研究中国农田下垫面变化对东亚区域气候的影响。结果表明:中国农田变化对气候影响具有冬季弱、夏季强的季节性变化,夏季气温和降水的差异在一些地区通过了95%的显著性检验;20世纪80年代农田扩张,林地、草地为主的植被类型转化为农田,植被变化区域的叶面积指数降低,反照率升高,且通过了95%的显著性检验,使得中国东部地区的气温由南到北呈现增加—减少—增加—减少的相间变化趋势,而降水的变化趋势大体相反;20世纪90年代农田面积减少,除东北地区外,农田变化引起的植被变化与80年代基本相反,叶面积指数变化、反照率以及由此导致的气候各要素也呈现大体相反的变化趋势;不同时期农田变化引起的植被类型转化的差异,使850 hPa风场变化趋势基本相反,可能是导致气温和降水变化趋势差异的主要原因之一。     

Modeling and analysis of the potential impacts on regional climate due to vegetation degradation over arid and semi-arid regions of China

The regional climate effects of vegetation change in arid and semi-arid regions of China, which has experienced serious grassland degradation, are investigated in this study using the Weather Research and Forecasting (WRF) regional climate model. Two long-term simulation experiments (from January 1, 1980 to March 1, 2010), one with the land cover derived from the original United States Geological Survey’s (USGS) data (denoted as CTL) and the other (denoted as SEN) with a modification of the former one by vegetation degradation in arid and semi-arid regions of China, are undertaken to investigate the influence of land cover change on regional climate over arid and semi-arid regions of China. The possible mechanisms of how land cover change affects the regional climate in arid and semi-arid regions of China are also examined. The simulation results indicate that when compared with the observation datasets, the WRF model simulates the spatial pattern of observed temperature and precipitation quite well. After vegetation degradation over the arid and semi-arid regions of China, the net radiation and evaporation are reduced mainly within the degraded areas in summer, consistent with the reduction in precipitation and the increase in 2-m air temperature (T2 m).     

Integrating global and regional analyses of the effects of climate change: A case study of land use in England and Wales

The purpose of this paper is to exemplify a means by which an integrated assessment can be made of global and regional effects on land use of climate change. This is achieved by use of data on the effects of climate change on world food prices as inputs to a regional land use allocation model.Data on world prices are drawn from a recent global study of climate change and crop yields. In a case study of England and Wales a land allocation model is used to infer changes of land use that are the product of the integrated effect of climate-induced global price changes and climate-related changes of yield in England and Wales. This combination of changed prices and yield potential is used to calculate the land use providing the highest returns for each of 155,235 1 km² cells of land in England and Wales for a future assumed for the year 2060 (without climate change) and then for that same environment with climate change. The difference between these two is then treated as an estimated effect resulting from climate change.     

A NUMERICAL SIMULATION OF THE EFFECT ON CHINESE REGIONAL CLIMATE DUE TO SEASONAL VARIATION OF LAND SURFACE PARAMETERS(PART I)

Sensitivity experiment is an important method to study the effect on regional climate due toseasonal variation of land surface parameters.Using China Regional Climate Model(CRCM)nested in CCM1.we first simulate Chinese regional climate,then two numerical sensitivityexperiments on the effect of vegetation and roughness length are made.The results show that:(1)If the vegetation is replaced with the monthly data of 1997.precipitation and land-surfacetemperature are both changed clearly,precipitation decreases and land surface temperatureincreases,but there is no regional correspondence between these changes.And the results aremuch better than the results when climate average vegetation was used in the CRCM.(2)If theroughness length is replaced with the monthly data of 1997,there is significant change on landsurface temperature,and there is very good regional correspondence between these changes.Butthe effect on precipitation is very small.     

The impact of land cover change on the atmospheric circulation

 The NCAR Community Climate Model (version 3), coupled to the Biosphere Atmosphere Transfer scheme and a mixed layer ocean model is used to investigate the impact on the climate of a conservative change from natural to present land cover. Natural vegetation cover was obtained from an ecophysiologically constrained biome model. The current vegetation cover was obtained by perturbing the natural cover from forest to grass over areas where land cover has been observed to change. Simulations were performed for 17 years for each case (results from the last 15 years are presented here). We find that land cover changes, largely constrained to the tropics, SE Asia, North America and Europe, cause statistically significant changes in regional temperature and precipitation but cause no impact on the globally averaged temperature or precipitation. The perturbation in land cover in the tropics and SE Asia teleconnect to higher latitudes by changing the position and strength of key elements of the general circulation (the Hadley and Walker circulations). Many of the areas where statistically significant changes occur are remote from the location of land cover change. Historical land cover change is not typically included in transitory climate simulations, and it may be that the simulation of the patterns of temperature change over the twentieth century by climate models will be further improved by taking it into account. Received: 27 May 1999 / Accepted: July 2000     

A numerical experiment study for effects of the grassland desertification on summer drought in North China

1IntroductionDManyobservationsandstudiesindicatethatthesummerrainfallinNorthChinadecreasessignificantlyduringrecenttwentyyears.Theobviousreductiontendencycanbeseenfromthevariationofpercentageofsummerrainfallanomaly(June--August)intheplainofNorthChina...     

全球陆地年降水量与ENSO关系的初步研究

用全球陆地月降水资料（PREC／L），研究了1948－2000年期间的ENSO事件与全球陆地年降水量的关系，对全盛分析的结果进行了蒙特卡洛模拟经验。结果表明，暖事件年全球陆地年降水量大范围地明显减小，显著的地区是：赤道西太平洋区，中国的华北，赤道中美洲区，孟加拉湾北部及尼泊尔，东澳大利亚区，印度西部及巴基斯坦南部，勒拿河以东地区，西欧及南极的威尔克斯等区域。在暖事件年，陆地年降水量增加地区不多，主要是南美的智利和阿根廷，东非索马里，肯尼亚和坦桑亚，中东的土耳其，伊拉克及伊朗，北非的利比亚和阿尔及利亚，西南非的纳米比亚及非洲南部的博茨瓦纳和津巴布韦。统计检验表明，暖事件年全球陆地年降水量减少的面积比降水量增加的面积要大，而且更为显著，将本文结果与早期的研究结果进行了比较，研究还指出，ENSO的年代际变化对上述地区降水的年代际变化影响不明显。但是80年代以后的暖事件对东澳大利亚干旱，中国的华北的干旱的影响比80年代前的影响更大。     

Sensitivity of carbon cycling in the European Alps to changes of climate and land cover

Assessments of the impacts of global change on carbon stocks in mountain regions have received little attention to date, in spite of the considerable role of these areas for the global carbon cycle. We used the regional hydro-ecological simulation system RHESSys in five case study catchments from different climatic zones in the European Alps to investigate the behavior of the carbon cycle under changing climatic and land cover conditions derived from the SRES scenarios of the IPCC. The focus of this study was on analyzing the differences in carbon cycling across various climatic zones of the Alps, and to explore the differences between the impacts of various SRES scenarios (A1FI, A2, B1, B2), and between several global circulation models (GCMs, i.e., HadCM3, CGCM2, CSIRO2, PCM). The simulation results indicate that the warming trend generally enhances carbon sequestration in these catchments over the first half of the twenty-first century, particularly in forests just below treeline. Thereafter, forests at low elevations increasingly release carbon as a consequence of the changed balance between growth and respiration processes, resulting in a net carbon source at the catchment scale. Land cover changes have a strong modifying effect on these climate-induced patterns. While the simulated temporal pattern of carbon cycling is qualitatively similar across the five catchments, quantitative differences exist due to the regional differences of the climate and land cover scenarios, with land cover exerting a stronger influence. The differences in the simulations with scenarios derived from several GCMs under one SRES scenario are of the same magnitude as the differences between various SRES scenarios derived from one single GCM, suggesting that the uncertainty in climate model projections needs to be narrowed before accurate impact assessments under the various SRES scenarios can be made at the local to regional scale. We conclude that the carbon balance of the European Alps is likely to shift strongly in the future, driven mainly by land cover changes, but also by changes of the climate. We recommend that assessments of carbon cycling at regional to continental scales should make sure to adequately include sub-regional differences of changes in climate and land cover, particularly in areas with a complex topography.     

基于三种WRF陆面过程方案的东南亚毁林增温响应研究

选取东南亚中南半岛地区作为模拟区域，基于高分辨率的遥感观测森林变化数据和WRF数值模式，设计毁林前后的两种情景对旱季气候进行模拟，评估NoahMP、CLM和Noah mosaic三种陆面过程方案对热带毁林增温响应的模拟能力。结果表明，CLM方案在模拟历史气温中有着更好的表现，Noah mosaic方案的结果存在明显低估。然而，对比毁林前后两种情景的模拟结果，本文发现，只有采用了"次格网"方式的Noah mosaic方案较好地模拟出毁林增温响应特征。在格网尺度采用"主导类型"计算方式的NoahMP方案没有合理地呈现出森林损失对区域气候的影响。理论上，CLM模式在计算中同时考虑格网内所有植被类型，然而本文发现CLM方案在主导类型不变的格网对森林损失比例不敏感，而且对毁林反馈的模拟结果与NoahMP方案的结果更接近。据此推测，在WRF模式耦合CLM方案的过程中，格网内参数处理方式可能产生了错误，实际采用的是"主导类型"方式。在模拟土地覆盖类型变化对气候的影响时，本文推荐使用Noah mosaic方案。同时，建议在未来版本的WRF模型中修正目前耦合的CLM方案关于次格网方法的处理方式，提供更合理的水热通量模拟。     

Parameterization of snow-free land surface albedo as a function of vegetation phenology based on MODIS data and applied in climate modelling

The aim of this study was to develop an advanced parameterization of the snow-free land surface albedo for climate modelling describing the temporal variation of surface albedo as a function of vegetation phenology on a monthly time scale. To estimate the effect of vegetation phenology on snow-free land surface albedo, remotely sensed data products from the Moderate-Resolution Imaging Spectroradiometer (MODIS) on board the NASA Terra platform measured during 2001 to 2004 are used. The snow-free surface albedo variability is determined by the optical contrast between the vegetation canopy and the underlying soil surface. The MODIS products of the white-sky albedo for total shortwave broad bands and the fraction of absorbed photosynthetically active radiation (FPAR) are analysed to separate the vegetation canopy albedo from the underlying soil albedo. Global maps of pure soil albedo and pure vegetation albedo are derived on a 0.5° regular latitude/longitude grid, re-sampling the high-resolution information from remote sensing-measured pixel level to the model grid scale and filling up gaps from the satellite data. These global maps show that in the northern and mid-latitudes soils are mostly darker than vegetation, whereas in the lower latitudes, especially in semi-deserts, soil albedo is mostly higher than vegetation albedo. The separated soil and vegetation albedo can be applied to compute the annual surface albedo cycle from monthly varying leaf area index. This parameterization is especially designed for the land surface scheme of the regional climate model REMO and the global climate model ECHAM5, but can easily be integrated into the land surface schemes of other regional and global climate models.     

1961-2016年中国西北地区陆地水分收支的年代际变化特征

利用观测气象数据集（CN05.1）、地表水文数据集（VIC-CN05.1）以及大气再分析数据（JRA55）分析了我国西北地区1961-2016年暖季（5-9月）陆地水分收支的长期和年代际变化特征。通过对陆地水分收支（Land Water Availability，LWA）时间序列作Mann-Kendall突变检验，将1961-2016年划分为3个时段进行进一步分析（P1：1961-1978年；P2：1979-2008年；P3：2009-2016年）。主要结论如下：在1961-2016年间西北地区LWA呈上升趋势，区域平均的LWA时间序列具有明显的年代际特征。三个时段的LWA距平百分率分别为-5.45%、-0.46%和13.99%，总体表现为"减少-不变-增加"的特征，尤其是近些年地表水资源增加明显。三个时段的LWA距平百分率空间分布差异显著，尤其在新疆中部、甘肃东部和陕西。西北地区总体上水汽通量输送和垂直速度与降水年代际变化特征基本一致，且区域特征明显。西北地区蒸发受降水、向下长波辐射通量和风速变化影响显著。     

Multi-year Simulations and Experimental Seasonal Predictions for Rainy Seasons in China by Using a Nested Regional Climate Model （RegCM_NCC）. Part Ⅰ： Sensitivity Study

A modified version of the NCAR/RegCM2 has been developed at the National Climate Center （NCC）, China Meteorological Administration, through a series of sensitivity experiments and multi-year simulations and hindcasts, with a special emphasis on the adequate choice of physical parameterization schemes suitable for the East Asian monsoon climate. This regional climate model is nested with the NCC/IAP （Institute of Atmospheric Physics） T63 coupled GCM to make an experimental seasonal prediction for China and East Asia. The four-year （2001 to 2004） prediction results are encouraging. This paper is the first part of a two-part paper, and it mainly describes the sensitivity study of the physical process paraxneterization represented in the model. The systematic errors produced by the different physical parameterization schemes such as the land surface processes, convective precipitation, cloud-radiation transfer process, boundary layer process and large-scale terrain features have been identified based on multi-year and extreme flooding event simulations. A number of comparative experiments has shown that the mass flux scheme （MFS） and Betts-Miller scheme （BM） for convective precipitation, the LPMI （land surface process model I） and LPMII （land surface process model Ⅱ） for the land surface process, the CCM3 radiation transfer scheme for cloud-radiation transfer processes, the TKE （turbulent kinetic energy） scheme for the boundary layer processes and the topography treatment schemes for the Tibetan Plateau are suitable for simulations and prediction of the East Asia monsoon climate in rainy seasons. Based on the above sensitivity study, a modified version of the RegCM2 （RegCM_NCC） has been set up for climate simulations and seasonal predictions.