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1.
SiB2和SiB3对高寒草甸和茶树地表能量通量模拟的比较 总被引：1，自引：1，他引：0
运用简单生物圈模式第2版(SiB2)和第3版(SiB3),分别模拟青藏高原两个观测站(那曲、安多)和长江三角洲苏州东山观测站的近地面能量收支,并与相应观测数据进行比较研究,分析SiB2、SiB3模拟结果和观测资料产生差异的原因,以此来认识上述地区地表能量收支特点。结果表明,SiB2和SiB3模拟的近地面能量通量与观测数据有较好的一致性。对感热通量,那曲和安多站SiB3比SiB2模拟的结果更接近观测资料,但苏州站SiB2模拟的结果与观测资料更吻合;对潜热通量,SiB3比SiB2模拟的日变化与观测资料更一致,SiB3的模拟结果与观测资料(除苏州站外)相关系数都在0.8以上;对地表土壤热通量,SiB2和SiB3模拟结果与观测数据相关系数都在0.8以上;对净辐射通量,SiB2和SiB3模拟结果与观测资料相关系数接近1.0。与SiB2相比,SiB3引用通用陆面模式的土壤描述并增加对冠层空间层温度、湿度和痕量气体的预报,使其能够改善潜热通量和土壤热通量的模拟,但对复杂下垫面的感热和净辐射通量模拟能力提高不明显。 相似文献
2.
通用陆面模式CLM在东亚不同典型下垫面的验证试验 总被引：20，自引：7，他引：13
利用野外观测资料,考察了通用陆面过程模式(CLM)对东亚地区3种典型下垫面(高原稀疏植被下垫面、森林、水田)的模拟能力.验证结果表明,在高原稀疏植被下垫面,CLM模拟的地表气温跟实测较为接近,同时CLM还可以较好地模拟出土壤温度随时间和深度的变化特征,但模式模拟的地面温度的幅值跟观测相比显著偏小;对于能量通量而言,除感热通量外,CLM所模拟出的其它能量通量的变化均与观测实况比较一致.对于淮河流域的森林下垫面,CLM所模拟出陆气间的各能量通量均与实测较为接近,尤以夏季(8月份)的模拟性能最好.对于水田下垫面,CLM模式较好地模拟出了各能量通量的主要变化特征及其季节差异,如水田的净辐射以及潜热通量夏季最大,而感热通量则是秋季最大等. 相似文献
3.
利用NOAH(The Community Noah Land Surface Model)、SHAW(Simultaneous Heat and Water)和CLM(Community Land Model)3个不同的陆面过程模式及兰州大学(Semi-Arid Climate Observatory and Laboratory,SACOL)2007年的观测资料,对黄土高原半干旱区的陆面过程进行了模拟研究。通过与观测值间的对比,考察不同陆面过程模式在半干旱区的适用性。研究结果表明:3个模式在半干旱区的模拟性能有较大差异。其中,CLM模式模拟的20 cm以上的浅层土壤温度最优,SHAW模式模拟的深层土壤温度最优;SHAW模式模拟的土壤含水量与观测值最为接近,而NOAH和CLM模式模拟值有较大偏差;3个模式均能较好地模拟地表反射辐射,其中SHAW模式模拟值与观测值的偏差最小;对地表长波辐射的模拟,CLM模式的模拟最优;3个模式均能较好地反映感热、潜热通量的变化趋势,其中CLM模式对感热的模拟性能优于其他两个模式,在有降水发生后的湿润条件下,CLM模式对潜热的模拟性能最优,而无降水的干燥条件下,CLM模式的模拟偏差最大,NOAH模式对冬季潜热的模拟最优。总体而言,CLM模式能够更好地再现半干旱区地气之间的相互作用,但模式对土壤含水量及干燥条件下的潜热通量的模拟较差,模式对半干旱区陆气间的水文过程还有待进一步的研究和改进。 相似文献
4.
Xiangxiang ZHANG Yongjiu DAI Hongzhi CUI Robert E. DICKINSON Siguang ZHU Nan WEI Binyan YAN Hua YUAN Wei SHANGGUAN Lili WANG Wenting FU 《大气科学进展》2017,34(9):1035-1046
Given the crucial role of land surface processes in global and regional climates, there is a pressing need to test and verify the performance of land surface models via comparisons to observations. In this study, the eddy covariance measurements from 20 FLUXNET sites spanning more than 100 site-years were utilized to evaluate the performance of the Common Land Model(Co LM) over different vegetation types in various climate zones. A decomposition method was employed to separate both the observed and simulated energy fluxes, i.e., the sensible heat flux, latent heat flux, net radiation, and ground heat flux, at three timescales ranging from stepwise(30 min) to monthly. A comparison between the simulations and observations indicated that Co LM produced satisfactory simulations of all four energy fluxes, although the different indexes did not exhibit consistent results among the different fluxes. A strong agreement between the simulations and observations was found for the seasonal cycles at the 20 sites, whereas Co LM underestimated the latent heat flux at the sites with distinct dry and wet seasons, which might be associated with its weakness in simulating soil water during the dry season. Co LM cannot explicitly simulate the midday depression of leaf gas exchange, which may explain why Co LM also has a maximum diurnal bias at noon in the summer. Of the eight selected vegetation types analyzed, Co LM performs best for evergreen broadleaf forests and worst for croplands and wetlands. 相似文献
5.
黑河实验区非均匀地表能量通量的数值模拟 总被引：12，自引：13，他引：12
利用三维非静力RAMS模拟研究了黑河实验区非均匀地表能量通量，模拟结果表明：绿洲地表净辐射通量较沙漠戈壁大；绿洲及沙漠戈壁下垫面上的Bowen比分别为0．4和4．0；夜间绿洲上整晚维持蒸发，并有负感热通量。模拟结果与测站实测结果与卫星反演值的对比研究指出，RAMS对绿洲下垫面潜热通量的模拟和沙漠戈壁下垫面感热通量的模拟与实测值基本一致。卫星遥感反演及数值模拟方法对净辐射的估算与实测较吻合，绿洲地表感热通量的卫星反演值较数值模拟结果更接近于实际，但潜热通量的模拟值则较卫星估算值更接近于实际；沙漠戈壁地表则是感热通量的模拟值较卫星反演值更接近于实际。上述分析为今后结合卫星遥感改进RAMS陆面过程参数化，使使用于模拟研究干旱区非均匀下垫面地气相互作用提供了可靠依据。 相似文献
6.
Simulation of the Bare Soil Surface Energy Balance at the Tongyu Reference Site in Semiarid Area of North China 
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下载免费PDF全文 ZHANG Xia 《大气和海洋科学快报》2010,3(6):330-335
The performance of a 1-D soil model in a semiarid area of North China was investigated using observational data from a cropland station at the Tongyu reference site of the Coordinated Enhanced Observing Period (CEOP) during the non-growing period, when the ground surface was covered with bare soil. Comparisons between simulated and observed soil surface energy balance components as well as soil temperatures and water contents were conducted to validate the soil model. Results show that the soil model could produce good simulations of soil surface temperature, net radiation flux and sensible heat flux against observed values with the RMSE of 1.54oC, 7.71 W m-2 and 27.79 W m-2, respectively. The simulated volumetric soil water content is close to the observed values at various depths with the maximal difference between them being 0.03. Simulated latent heat and ground heat fluxes have relatively lower errors in relative to net radiation and sensible heat flux. In conclusion, the soil model has good capacity to simulate the bare soil surface energy balance at the Tongyu cropland station and needs to be further tested in longer period and at more sites in semiarid areas. 相似文献
7.
Summary Strong stable layers are a common occurrence during western Colorado's winter. Analysis of radiosonde observations indicate wintertime boundary layer heights are near 500 m. The terrain in this region consists of mountains that rise approximately 1500–2000 m above the ground to the east, providing an effective blocking barrier. An experiment is described to observe upwelling and downwelling, longwave and shortwave radiative fluxes at two sites in western Colorado during January and February 1992, for combinations of clear, cloudy, snow covered, and bare ground periods. Analysis of the observations and the surface energy budget for typical Bowen ratios provides a better understanding of the role of radiation in maintaining and destroying stable layers.During the day, the surface received a net gain of energy from radiation, while at night there was a net loss. Over snow, the 24-hour net radiative flux was small and either positive or negative. Over bare soil, the 24-hour net radiative flux was positive but still small. There is little difference in the net radiative flux between clear and cloudy days; the reduction of the incident solar flux by clouds is nearly compensated by the hindering of the longwave cooling. The cumulative effects of the 24-hour net radiative flux were negative over snow early in the experiment. The 24-hour values shifted to near zero as the snow albedo decreased and were positive for bare ground.If the daytime net radiative flux is partitioned into sensible and latent heat flux using typical Bowen ratios, the daytime sensible heat available for destroying boundary layers is small for the low solar angles of the winter season. With a Bowen ratio of 0.5, the daytime sensible heat flux available is only 0.3 to 1.2 MJ m–2 over a snow surface and 1.4 to 2.3 MJ m–2 over soil. These heat fluxes will not build a deep enough boundary layer to break a typical wintertime inversion. The 24-hour sensible heat flux was negative at both sites for the entire experiment with this Bowen ratio.The radiation observations and the use of typical Bowen ratios lead to the conclusion that the net radiation will sustain or strengthen a stable atmosphere in the winter season in western Colorado. Analysis of the radiosonde observations confirm this result as the boundary layer depths were less than 500 m early in the experiment and grew to only 700 m later in the experiment.With 12 Figures 相似文献
8.
Three-year Variations of Water, Energy and CO$_2$ Fluxes of Cropland and Degraded Grassland Surfaces in a Semi-arid Area of Northeastern China 总被引：1，自引：0，他引：1
Based on 3 years （2003-05） of the eddy covariance （EC） observations on degraded grassland and cropland surfaces in a semi-arid area of Tongyu （44°25′N, 122°52′E, 184 m a.s.1.）, Northeast China, seasonal and annual variations of water, energy and CO2 fluxes have been investigated. The soil moisture in the thin soil layer （at 0.05, 0.10 and 0.20 m） clearly indicates the pronounced annual wet-dry cycle; the annual cycle is divided into the wet （growing season） and dry seasons （non-growing season）. During the growing season （from May to September）, the sensible and latent heat fluxes showed a linear dependence on the global solar radiation. However, in the non-growing season, the latent heat flux was always less than 50 W m^-2, while the available energy was dissipated as sensible, rather than latent heat flux. During the growing season in 2003-05, the daily average sensible and latent heat fluxes were larger on the cropland surface than on the degraded grassland surface. The cropland ecosystem absorbed more CO2 than the degraded grassland ecosystem in the growing season in 2003-05. The total evapotranspiration on the cropland was more than the total precipitation, while the total evapotranspiration on the degraded grassland was almost the same as the total annual precipitation in the growing season. The soil moisture had a good correlation with the rainfall in the growing season. Precipitation in the growing season is an important factor on the water and carbon budget in the semi-arid area. 相似文献
9.
Kusuma G. Rao 《Boundary-Layer Meteorology》1986,36(3):283-294
Based on the theory given by Saltzman and Ashe (1976), sensible heat fluxes are calculated for the active and break phases of the southwest monsoon over the Indian region. The conclusion drawn is that the sensible heat flux is generally larger during the break monsoon situation when compared with that for the active monsoon situation. The synoptic heat flux is negligible when compared with mean and diurnal heat fluxes over the Indian region even during the monsoon season. 相似文献
10.
基于陆面模式Noah-MP的不同参数化方案在半干旱区的适用性 总被引：2，自引：2，他引：0
针对陆面模式Noah-MP对兰州大学半干旱气候与环境观测站（SACOL）2009年8月地表热通量模拟值偏差大的问题,通过分析相关物理过程和模拟试验来探究偏差的来源,并确定合适的参数化方案:采用Chen97方案计算感热输送系数可以改善感热通量的模拟;采用Jarvis气孔阻抗方案能增大植被蒸腾,改进模式对潜热通量的模拟效果,同时也使热通量在感热和潜热间的分配比例合理;采用LP92方案可减小土壤蒸发阻抗并有利于土壤蒸发,使得模式对潜热通量的模拟效果变好。不同参数化方案的组合试验表明:同时采用2组或3组新的参数化方案组合可以进一步减小模拟的地表感热和潜热通量的均方根误差,但是土壤湿度和温度的模拟效果并没有同步改善。 相似文献
11.
利用第三次青藏高原大气科学观测试验数据,对高原不同地区感热、潜热交换等湍流输送特征进行了分析,并进一步对比研究了其与气象环境因子的相关关系。结果表明:（1）高原各站之间感热和潜热的差异性较大,但大多在雨季潜热会大于感热。干燥的狮泉河站属于高寒荒漠地区,降水极少,全年感热都远大于潜热,波文比年平均值可达到20.0;湿润的比如站和嘉黎站潜热在4～10月均显著大于感热,波文比在4～10月的数值范围在0.27～0.88。（2）高原感热和潜热通量的季节变化与高原季风所处的地理位置有密切关系,高原中部的感热通量在3～5月达到最大值,而高原西部则在4～6月最大,可能与高原季风的活动有关。（3）通过与气象要素的相关分析表明,高原西部狮泉河站感热与地气温差的正相关关系最为显著,全年的相关系数可以达到0.905,在4个季节相关系数也均大于0.79,这可能与下垫面是裸地有关;高原中部安多站和那曲站感热与风速的正相关在夏季最为显著,比如站感热与风速的正相关在冬季最为明显,而狮泉河站感热与风速在春、夏季均有着十分显著的正相关。 相似文献
12.
东亚夏季风边缘摆动区陆面能量时空分布规律及其与气候环境的关系 总被引：3，自引：1，他引：2
东亚夏季风边缘摆动区既是气候敏感区,也是生态脆弱区和农牧交错带,其特殊陆面能量空间分布格局和演变特征对理解该区域天气和气候变化有重要意义。然而受限于陆面观测资料缺乏,对这部分陆面特征的认识仍非常有限。通过对34 a陆面模拟集成产品的分析,发现夏季风边缘摆动区内潜热和感热通量在空间上表现出明显的过渡特征,由摆动区外的相对均衡状态进入到摆动区内的“突变转换”;陆面能量平衡具有明显的区域特征,能量平衡各分量在纬向和经向都表现出了“阶梯型”的变化。就演变而言,区域平均感热和潜热没有表现出规律性的递减或递增趋势,波动幅度在±20%以内,但在20世纪末存在一个较为明显的摆动相位转换:1997年之前夏季风边缘摆动区夏季风相对活跃,潜热通量总体高于其气候值而感热通量则低于其气候值,之后出现了相反的现象。此外,区内感热和潜热通量对气候环境干湿性质非常敏感,两者存在明显的线性关系。 相似文献
13.
Turbulent surface heat fluxes (latent and sensible heat) are the two most important parameters through which air–sea interaction takes place at the ocean–atmosphere interface. These fluxes over the global ocean are required to drive ocean models and to validate coupled ocean–atmosphere global models. But because of inadequate in situ observations these are the least understood parameters over the tropical Indian Ocean. Surface heat fluxes also contribute to the oceanic heat budget and control the sea surface temperature in conjunction with upper ocean stratification and ocean currents. The most widely used flux products in diagnostic studies and forcing of ocean general circulation models are the ones provided by the National Centres for Environment Prediction (NCEP) reanalysis. In this study we have compared NCEP reanalysed marine meteorological parameters, which are used for turbulent heat fluxes, with the moored buoy observation in the south-eastern Arabian Sea. The NCEP latent heat flux (LHF) and sensible heat flux (SHF) derived from bulk aerodynamic formula are also compared with that of ship and buoy derived LHF and SHF. The analysis is being carried out during the pre-monsoon and monsoon season of 2005. The analysis shows that NCEP latent as well as sensible heat fluxes are largely underestimated during the monsoon season, however, it is reasonably comparable during the pre-monsoon period. This is largely due to the underestimation of NCEP reanalysis air temperature (AT), wind speed (WS) and relative humidity (RH) compared to buoy observations. The mean differences between buoy and NCEP parameters during the monsoon (pre-monsoon) period are ~21% (~14%) for WS, ~6% (~3%) for RH, and ~0.75% (0.9%) for AT, respectively. The sudden drop in AT during rain events could not be captured by the NCEP data and, hence, large underestimations in SHF. During the pre-monsoon period, major contribution to LHF variations comes from WS, however, both surface winds and relative humidity controls the LHF variations during the monsoon. LHF is mainly determined by WS and RH during the monsoon and, WS is the main contributor during the pre-monsoon. 相似文献
14.
根据1998年南海季风试验西沙海面铁塔梯度观测资料，利用总体（Bulk）系数法和多层结通量廓线法对西沙海面的海-气通量进行了估算，得出两种方法估算的潜热通量、感热通量基本一致。总体系数法估算的潜热通量比多层结通量廓线法略大1～3 W·m-2，感热通量小0～1.5 W·m-2。一般而言，季风爆发期间潜热输送逐渐增加；季风爆发前期夜间潜热通量比季风爆发后期大；季风爆发后期，白天潜热通量明显大于爆发初期和中期。感热通量季风爆发前海面向大气输送，爆发后期大气向海面输送。动量通量和摩擦速度随风速增加。 相似文献
15.
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
16.
黄土高原半干旱区夏季晴天陆面特征模拟与观测对比分析 总被引：1，自引：0，他引：1
以甘肃定西为例,利用中尺度模式MM5模拟了黄土高原半干旱区夏季晴人的陆面特征,并与观测资料进行对比分析。结果表明,对气温、土壤热通量、辐射、感热通量的模拟结果与观测比较一致,而对比湿、地表温度、潜热通量的模拟结果与观测偏差稍大。夏季晴天,定西地区的地表温度日最高值出现时间较13最高气温出现时间早了3h,但两者日最低值出现时间相同;10cm深度处的土壤温度存在明显的日变化,而40、80cm深度处无明显的日变化;空气湿度较低,夜晚比湿的变化与露水的凝结量变化时间一致;土壤热通量呈典型的单峰型日变化特征,日最大值出现在13：00,与太阳短波辐射与地表反射辐射日最大值出现的时间相同;在半干旱区感热通量明显大于潜热通量,热通量以感热通量为主;边界层高度最高可达到2100m左右,比干旱区敦煌的低1000m左右。 相似文献
17.
The land surface processes of the Noah-MP and Noah models are evaluated over four typical landscapes in the Haihe River Basin(HRB) using in-situ observations. The simulated soil temperature and moisture in the two land surface models(LSMs) is consistent with the observation, especially in the rainy season. The models reproduce the mean values and seasonality of the energy fluxes of the croplands, despite the obvious underestimated total evaporation. Noah shows the lower deep soil temperature. The net radiation is well simulated for the diurnal time scale. The daytime latent heat fluxes are always underestimated, while the sensible heat fluxes are overestimated to some degree. Compared with Noah, Noah-MP has improved daily average soil heat flux with diurnal variations. Generally, Noah-MP performs fairly well for different landscapes of the HRB. The simulated cold bias in soil temperature is possibly linked with the parameterized partition of the energy into surface fluxes. Thus, further improvement of these LSMs remains a major challenge. 相似文献
18.
Measurements Of Turbulence Transfer In The Near-Surface Layer Over The Southeastern Tibetan Plateau 总被引：5，自引：0，他引：5
Lingen Bian Zhiqiu Gao Qiangde Xu Longhua Lu Yanjie Cheng 《Boundary-Layer Meteorology》2002,102(2):281-300
Turbulent flux measurements at Qamdo site over the Tibetan Plateau during TIPEX from May 18 to June 30, 1998 are presented. Sensible heat dominated,accounting for about 66% of the available energy (the sum of net radiation and soil heat flux) prior to the monsoon(dry period), reducing to about 31%, with latent heat increased to about 56% of available energy,in the monsoon season (wet period). Surface energy budget closure on average was about 0.80 (0.85)prior to the monsoon and 0.89 (0.76) during the monsoon using eddy correlation (profile) methods. The sum of latent and sensible heat fluxes calculated from the flux-profilemethod was smaller by about 15% than that from eddy correlation. Martano's method is used toestimate the surface aerodynamic roughness length z0 and zero plane displacement d from singlelevel sonic anemometer data, giving d = 0.12 m and z0 = 0.08 m. The overall neutral dragcoefficient (CDN) and scalar coefficient (CHN) were found to be CDN = 0.0055and CHN = 0.0059 in the southeastern area of Tibet. Their variations with the mean wind speed at 10 m are discussed. 相似文献
19.
青藏高原东南部复杂地形区不同天气状况下陆气能量交换特征分析 总被引：5，自引：2，他引：3
青藏高原地理环境复杂,已有大气陆面-边界层研究工作多集中于不同下垫面,很少有对复杂地形区的研究。本文利用青藏高原东南部林芝地区2013年5月20日至7月9日四个野外试验站点的观测资料,分析了不同天气条件下,高原复杂地形区不同下垫面的陆-气能量交换特征。结果表明:在各站向下短波辐射基本一致的情况下,地形较陡的北坡阔叶林站感热通量远大于其他3个站点;下垫面植被覆盖最多的南面麦田站潜热通量最大。各站能量通量有明显的日变化特征,晴天时,感热通量和净辐射明显大于阴雨天,而潜热通量随天气状况变化不大。青藏高原复杂地形环境比不同天气条件对于感热通量的影响更显著;不同地形阴雨天时对于潜热通量有明显的影响。当南亚季风槽前的西南暖湿气流影响到林芝地区时,该地区以阴雨天为主,反之则以晴天为主。林芝地区地-气通量的月内变化明显受南亚季风活动的影响。 相似文献
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利用2008年4~5月大理国家气候观象台近地面层观测系统的梯度、涡动相关通量观测资料,结合背景场环流分析,分析了西南季风爆发前后大理近地面层的风速、风向变化特征、风速廓线和垂直切变变化特征以及动量、感热和潜热通量变化特征。结果显示:西南季风爆发前,大理近地层风向以东南风为主,平均风速较大;风速日变化的双峰型特征较显著,风速的垂直切变大,动量通量数值较大且日变化特征较明显。西南季风爆发后,大理近地层西北风频率显著增加,平均风速减小;风速日变化以单锋型为主,风速垂直切变较前期显著减小,动量通量数值减小而日变化特征较不显著。西南季风开始前后大理地气热量交换都以潜热为主,西南季风开始前一旬期间,潜热通量的逐日变化特点是随时间逐渐减少,感热通量逐渐增大,二者差值逐渐减小;西南季风开始后潜热通量的逐日变化为逐渐增大而感热通量逐渐减少,二者差值逐渐增大。就月平均值的日变化而言,潜热通量峰值变化不大,雨季略低于干季的4月;感热通量4~6月的月平均逐月降低。其原因既与雨季天气的变化有关,也与下垫面状况的改变相联系。 相似文献