共查询到19条相似文献，搜索用时 218 毫秒
1.
植被覆盖度对兰州地区气象场影响的模拟研究 总被引：5，自引：0，他引：5
利用WRF(Weather Research and Forecasting)模式耦合Noah陆面过程模式,模拟了兰州地区冬季气象场,并用观测资料对模拟结果进行了检验。利用2006年中分辨率成像分光辐射计(MODIS)植被归一化指数(NDVI)计算得到的植被覆盖度替换模式默认的植被覆盖度,研究了植被覆盖度对WRF模式模拟结果的影响。结果表明,新的植被覆盖度数据使研究区域的地表反照率减小,发射率增加,感热通量白天增加、夜间减小;还明显地改进了WRF模式对近地面温度和风速的模拟;植被覆盖度对地表蒸发有很大影响,冬季干旱半干旱地区的植被基本处于休眠状态,地表蒸发以直接蒸发为主,使用新的植被覆盖度数据后,模拟区域的植被覆盖度增加,地表蒸发减小,近地面水汽含量减少,WRF模式模拟的边界层高度增大。 相似文献
2.
土壤-植被-大气系统水分散失机理的数值模拟 总被引：8，自引：0，他引：8
以Eeardorff(1978)提出的陆面参数化方案和Noilhan等人(1989)土壤水分参数化方案为基础,对陆面物理过程参数化方案进行了改进,在模式中较详细地考虑了植被和地面的各种物理参量如地面和叶面的反射率和发射率,净叶面面积指数,植被的物理阻抗等,并与大气边界层模式耦合。应用该模式模拟了沙漠及绿洲地区不同植被覆盖率情况下的蒸散量、土壤含水量和表面温度的日变化和连续变化特征;对不同植被覆盖率的热量平衡特征进行了比较。结果表明该模式较好地反映了地表蒸散3阶段的变化趋势特征,揭示出下垫面热量平衡分量间的相互转换过程。该模式可以用于中尺度的气象和区域气候模式,模拟和预测不同植被覆盖情况下近地层的热量输送和水分散失情况。 相似文献
3.
利用1992-2001年10a逐日降水、气温、湿度、风速和气压资料，使用气候要素逐步插值方法，修改VIC模式同一栅格中多种覆盖类型蒸发的计算方法，采用遥感等4种地表覆盖类型，考虑植被分布不均匀性，计算各种植被类型对地表水循环的贡献，结果表明：1）均匀落叶阔叶林地表年平均流量误差为-24．82％，均匀农田地表年平均流量误差为21．82％，《中国资源与环境数据库（1：400万）》（REDC）地表年平均流量误差为-14．32％，遥感地表的年平均流量误差最小，为1．43％，与实测吻合。2）采用均匀落叶阔叶林地表类型计算的蒸散，与降水年平均分布一致，与地形无关；均匀农田地表类型计算的蒸散，受地形影响明显；REDC地表类型计算的蒸散空间分布与地表植被类型有较好的对应关系。3）VIC-3L具有描述各类地表类型的能力，能够模拟出同一网格单元中多种植被类型对地表蒸散、径流等的作用，计算得到的蒸散、蒸发、径流等地表水平衡分量和空间分布显示出与均匀地表类型结果明显的不同。4）应用遥感地表覆盖类型，计算的地面蒸散、径流、土壤湿度和积雪升华的空间分布表明，地面蒸散受植被类型的影响是显著的。 相似文献
4.
卫星遥感藏北高原非均匀陆表地表特征参数和植被参数 总被引：20，自引：0，他引：20
卫星遥感在研究青藏高原北部地区(藏北高原地区)非均匀陆表地表特征参数和植被参数时有其独到的作用.作者提出了基于NOAA-14 AVHRR资料推算藏北高原地区地表特征参数和植被参数的方案,并把其用于全球能量水循环之亚洲季风青藏高原试验(GAME/Tibet)试验区.同时利用3个景的NOAA-14 AVHRR资料进行了分析研究,得到了一些有关藏北地区非均匀地表的区域地表特征参数(地表反射率、地表温度)和植被参数(INDV、植被覆盖度和叶面指数ILA). 相似文献
5.
CoLM模式地表温度变分同化研究 总被引：2，自引：1，他引：1
本文采用变分方法对通用陆面模式 (CoLM) 中的地表温度进行同化.同化伴随约束条件采用CoLM模式中的地表及植被能量平衡方程,调节因子采用裸土及植被蒸发比.采用美国通量网 (AmeriFlux) 中的Bonville站数据对同化方法进行了单点验证,验证结果表明同化后地表温度以及蒸散结果更加接近于实测值.选取中国华北地区对同化方法进行区域验证,结果显示每天仅采用白天一次观测值对地表温度进行同化的方法是有效的.通过对同化前后地表温度误差直方图比较可以发现,在有MODIS观测值的区域,同化后白天地表温度误差大大降低,同时,同化后地表蒸散空间分布图也发生了变化.单点验证以及区域验证结果都表明了变分同化方法是可靠的.变分同化方法可以改进陆面模式模拟结果,对于地表过程研究中的植被生态、水文等研究具有重要意义,同时,陆面模式可以与数值预报模式进行耦合,改进数值预报结果. 相似文献
6.
对临海沙漠地区非均匀地表区域地表能量通量和蒸发(蒸散)的研究,是一个十分重要但又是一个难点问题。本文提出了1个基于卫星遥感和地面观测的参数化方案,并把其应用于沙特阿拉伯吉达地区,利用1个景的陆地资源卫星Landsat-7E^TM^ 资料进行了分析研究,得到了一些有关临海沙漠地区非均匀地表区域地表特征参数、植被参数和地表能量通量的新概念。最后讨论了所提出的参数化方案的适用范围和需改进之处。 相似文献
7.
8.
基于中国植被数据的陆面覆盖及其对陆面过程模拟的影响 总被引：6，自引：2，他引：4
本文基于中国1:100万植被图、马里兰大学AVHRR森林覆盖资料和中国753个气象站点40年的降水气温资料, 发展了一套用于气候模拟的中国陆面覆盖资料(Chinese land cover derived from vegetation map, 简称CLCV)。该套资料与CLM(Community Land Model)原来所用的MODIS (Moderate Resolution Imaging Spectroradiometer) 陆面覆盖资料相比有较大不同: 其中裸土比例减少了14.5%, 森林、灌木、草原和农作物比例分别增加了3.3%、4.8%、4.4%和0.3%, 冰川、湖泊和湿地比例分别增加了0.4%、0.8%和0.6%。将CLCV和MODIS资料分别与全国土地资源概查汇总结果分省统计资料和基于中国1 km土地利用图的土地利用资料比较表明, CLCV与两者较为接近。最后, 利用CLM模式分别采用CLCV与MODIS陆面覆盖资料在中国区域内进行数值模拟, 结果显示, 使用CLCV资料所模拟的蒸散增加了约7.7 mm/a; 地表反照率、 感热和径流分别减小了约0.7%、 0.3 W/m2和7.6 mm/a; 与MODIS卫星反演地表反照率和GRDC (Global Runoff Data Centre) 径流资料比较表明, 利用CLCV资料所模拟的地表反照率有一定改进, 并能基本模拟出径流分布趋势。 相似文献
9.
西北干旱区及高原上卫星遥感非均匀地表区域能量通量研究 总被引：3，自引：1，他引：3
介绍了目前利用Landsat TM和NOAA/AVHRR遥感资料进行非均匀地表区域地表能量通量和蒸发(蒸散)量研究的进展和存在的难点问题，并提出了解决问题的可能途径。 相似文献
10.
上海城市精细化地表温度分布模拟 总被引：2，自引：0，他引：2
本文引入了一种模拟城市复杂下垫面地表温度的方法,该方法基于地表辐射参数化方案（NARP）计算城市净辐射通量,然后利用客观滞后模型OHM计算地表储热通量,再利用强迫恢复法计算表面温度。通过上海地区高分辨率卫星资料获取不同地表类型覆盖比例,以每个格点中各地表覆盖类型所占面积比例为权重计算格点的平均地表温度,并对2013年8月12日上海地区地表温度进行模拟。结果表明：上海城市下垫面与其他类型下垫面相比,地表温度白天升高较快,而夜间下降较慢。模拟结果与MODIS陆面温度及地面观测资料进行比较,模拟的上海地表温度分布结构更精细,与气象站观测值较接近。 相似文献
11.
Effects of Crop Growth and Development on Land Surface Fluxes 总被引：2，自引：0，他引：2
In this study, the Crop Estimation through Resource and Environment Synthesis model (CERES3.0) was coupled into the Biosphere-Atmosphere Transfer Scheme (BATS), which is called BATS CERES, to represent interactions between the land surface and crop growth processes. The effects of crop growth and development on land surface processes were then studied based on numerical simulations using the land surface models. Six sensitivity experiments by BATS show that the land surface fluxes underwent substantial changes when the leaf area index was changed from 0 to 6 m2 m-2. Numerical experiments for Yucheng and Taoyuan stations reveal that the coupled model could capture not only the responses of crop growth and development to environmental conditions, but also the feedbacks to land surface processes. For quantitative evaluation of the effects of crop growth and development on surface fluxes in China, two numerical experiments were conducted over continental China: one by BATS CERES and one by the original BATS. Comparison of the two runs shows decreases of leaf area index and fractional vegetation cover when incorporating dynamic crops in land surface simulation, which lead to less canopy interception, vegetation transpiration, total evapotranspiration, top soil moisture, and more soil evaporation, surface runoff, and root zone soil moisture. These changes are accompanied by decreasing latent heat flux and increasing sensible heat flux in the cropland region. In addition, the comparison between the simulations and observations proved that incorporating the crop growth and development process into the land surface model could reduce the systematic biases of the simulated leaf area index and top soil moisture, hence improve the simulation of land surface fluxes. 相似文献
12.
土地利用变化对长江流域气候及水文过程影响的敏感性研究 总被引：6，自引：0，他引：6
使用区域气候模式(RegCM3)和大尺度汇流模型(LRM), 研究土地利用/植被覆盖变化对长江流域气候及水文过程的影响。RegCM3嵌套于欧洲数值预报中心 (ECMWF) 再分析资料ERA40, 分别进行了中国区域在实际植被和理想植被分布情况下两个各15年 (1987～2001年) 时间长度的积分试验。随后, RegCM3 两个试验的输出径流结果分别用来驱动LRM, 研究土地利用/植被覆盖变化对长江流域河川径流的影响。研究结果指出, 中国当代土地利用变化对长江流域降水、蒸散发、径流深及河川径流等水文气候要素的改变较大, 对气温的改变并不明显。土地利用变化引起长江干流河川径流量在夏季(6～8月)有所增加, 并且越向下游增加幅度越大, 其中大通站径流量增加接近15%。总体而言, 土地利用改变加剧了长江流域夏季水循环过程, 使得夏季长江中下游地区降水增多, 径流增大。 相似文献
13.
Regional estimates of evapotranspiration over Northern China using a remote-sensing-based triangle interpolation method 总被引：1，自引：0，他引：1
Regional estimates of evapotranspiration (ET) are critical for a wide range of applications. Satellite remote sensing is a promising tool for obtaining reasonable ET spatial distribution data. However, there are at least two major problems that exist in the regional estimation of ET from remote sensing data. One is the conflicting requirements of simple data over a wide region, and accuracy of those data. The second is the lack of regional ET products that cover the entire region of northern China. In this study, we first retrieved the evaporative fraction (EF) by interpolating from the difference of day/night land surface temperature ( T ) and the normalized difference vegetation index (NDVI) triangular-shaped scatter space. Then, ET was generated from EF and land surface meteorological data. The estimated eight-day EF and ET results were validated with 14 eddy covariance (EC) flux measurements in the growing season (July-September) for the year2008 over the study area. The estimated values agreed well with flux tower measurements, and this agreement was highly statistically significant for both EF and ET (p <0.01), with the correlation coefficient for EF (R2 =0.64) being relatively higher than for ET (R2 =0.57). Validation with EC-measured ET showed the mean RMSE and bias were 0.78 mm d-1 (22.03 W m-2 ) and 0.31 mm d-1 (8.86 W m-2 ), respectively. The ET over the study area increased along a clear longitudinal gradient, which was probably controlled by the gradient of precipitation, green vegetation fractions, and the intensity of human activities. The satellite-based estimates adequately captured the spatial and seasonal structure of ET. Overall, our results demonstrate the potential of this simple but practical method for monitoring ET over regions with heterogeneous surface areas. 相似文献
14.
Effects of crop growth and development on regional climate: a case study over East Asian monsoon area 总被引：1，自引：0，他引：1
In this study, the CERES phenological growth and development functions were implemented into the regional climate model, RegCM3 to give a model denoted as RegCM3_CERES. This model was used to represent interactions between regional climate and crop growth processes. The effects of crop growth and development processes on regional climate were then studied based on two 20-year simulations over the East Asian monsoon area conducted using the original regional climate model RegCM3, and the coupled RegCM3_CERES model. The numerical experiments revealed that incorporating the crop growth and development processes into the regional climate model reduced the root mean squared error of the simulated precipitation by 2.2–10.7% over north China, and the simulated temperature by 5.5–30.9% over the monsoon region in eastern China. Comparison of the simulated results obtained using RegCM3_CERES and RegCM3 showed that the most significant changes associated with crop modeling were the changes in leaf area index which in turn modify the aspects of surface energy and water partitions and lead to moderate changes in surface temperature and, to some extent, rainfall. Further analysis revealed that a robust representation of seasonal changes in plant growth and developmental processes in the regional climate model changed the surface heat and moisture fluxes by modifying the vegetation characteristics, and that these differences in simulated surface fluxes resulted in different structures of the boundary layer and ultimately affected the convection. The variations in leaf area index and fractional vegetation cover changed the distribution of evapotranspiration and heat fluxes, which could potentially lead to anomalies in geopotential height, and consequently influenced the overlying atmospheric circulation. These changes would result in redistribution of the water and energy through advection. Nevertheless, there are significant uncertainties in modeling how monsoon dynamics responds to crop modeling and more research is needed. 相似文献
15.
利用MERIS和AATSR资料估算黄土高原塬区蒸散发量研究 总被引：8，自引：7，他引：1
基于陆面能量平衡原理,通过对搭载在欧洲空间局环境卫星(Environmental Satellite,ENVI-SAT)上中分辨率影像光谱仪(Medium Resolution Imaging Spectrometer,MERIS)2005年6月7,11和27日的遥感观测资料进行大气纠正等预处理后,得到估算瞬时蒸散发量所需要的地表反照率和植被覆盖度等值,并利用分裂窗法和ENVISAT上搭载的先进的沿轨迹扫描辐射计(Advanced Along-TrackScanning Radiometer,AATSR)的观测资料进行了地表温度的反演,进一步估算出黄土高原塬区午间瞬时净辐射、感热通量和土壤热通量。结合与卫星遥感观测资料同期研究区域气象站的太阳辐射、气温、日照时数和风速等气象要素资料,充分考虑到植被冠层和陆地表面对蒸散发量的不同影响,发展了一个可以估算陆面潜热的简化模型,并将瞬时蒸散发量转化为日蒸散发量。对卫星遥感估算的潜热通量,利用黄土高原塬区陆面过程野外观测试验(Loess Plateau land surface process field Experiments,LOPEXs)的地面通量观测资料进行验证,结果表明:二者最大相对差异为10.9%,最小相对差异为4.8%,并对差异误差产生的原因进行了分析和探讨。 相似文献
16.
Human-induced land use changes and the resulting alterations in vegetation features are major but poorly recognized drivers of regional climatic patterns.In order to investigate the impacts of anthropogenically-induced seasonal vegetation cover changes on regional climate in China,harmonic analysis is applied to 1982-2000 National Oceanic and Atmospheric Administration(NOAA) Advanced Very High Resolution Radiometer(AVVHRR)-derived normalized difference vegetation index(NDVI) time series(ten day interval data).For two climatic divisions of South China,it is shown that the first harmonic term is in phase with air temperature,while the second and third harmonics are in phase with agricultural cultivation.The Penman-Monteith Equation and the Complementary Relationship Areal Evapotranspiration(CRAE) model suggest that monthly mean evapotranspiration is out of phase with temperature and precipitation in regions with signiffcant second or third harmonics.Finally,seasonal vegetation cover changes associated with agricultural cultivation are identiffed:for cropped areas,the temperature and precipitation time series have a single maximum value,while the monthly evapotranspiration time series has a bimodal distribution.It is hypothesized that multi-cropping causes the land surface albedo to sharply increase during harvesting,thereby altering the energy distribution ratio and contributing to observed seasonal vegetation cover changes. 相似文献
17.
植被变化对中国区域气候的影响Ⅱ:机理分析 总被引：9，自引：1，他引：9
在利用区域气候模式（RegCM2）对中国植被变化的气候影响进行了数值模拟研究的基础上,该文着重对其中可能的机理进行了分析,结果表明:植被变化对地-气系统的能量平衡具有重要影响。植被变化使地表释放的有效通量（感热+潜热）发生变化,同时有效通量中的感热。潜热分配,即波恩比亦会发生改变,从而导致大气湿静力能分布的变化,使大气层结及垂直运动发生相应改变,这会进一步影响到大气水汽输送情况,井与相应的垂直运动变化结合最终导致降水的变化。另外,由于植被变化造成的地表蒸散及上壤持水能力的变化,会使土壤含水量、地表径流等也发生明显的变化。 相似文献
18.
19.
本文利用卫星遥感资料以及常规气象资料驱动基于地表净辐射、植被指数、平均气温和日温差的蒸散模型来估测日实际蒸散量,并与栾城站涡动相关法测量的实际蒸散作对比验证。定性分析了实际蒸散与各相关影响因子的时空变化规律;通过蒸散干旱指数（EDI）分析华北地区的干旱分布特点,并分别与PDSI指数和降水距平百分率作对比。结果表明：ET模型估测的蒸散值与实测值的相关性很好,其模拟精度对于大面积干旱监测的空间尺度上是可用的;EDI距平指数表征干旱分布的空间分辨率较高,且对旱情的指示和干旱程度的判定比较可靠。 相似文献