共查询到19条相似文献，搜索用时 281 毫秒
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本文简要介绍了包括三部分观测的安徽淮南长期野外试验观测站,特别是土壤-植被-大气的集中观测,对小塔运行前三个月(2018年6月至8月)的数据,并结合同一时段大塔获得的数据,进行了初步分析.结果表明这些资料有合理的变化特征,日变化和夏季值特征显著,各月份间气象变化有明显差异.土壤水分和温度受降雨影响,在不同的下垫面条件下表现出不同的变化.土壤CO2日平均浓度在2 cm和10 cm处分别为1726和4481 ppm.2018年夏季土壤CO2浓度随土壤体积含水量的变化而变化,但与土壤温度呈弱相关. 相似文献
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《大气和海洋科学快报》2021,(1)
本文简要介绍了包括三部分观测的安徽淮南长期野外试验观测站,特别是土壤-植被-大气的集中观测,对小塔运行前三个月(2018年6月至8月)的数据,并结合同一时段大塔获得的数据,进行了初步分析.结果表明这些资料有合理的变化特征,日变化和夏季值特征显著,各月份间气象变化有明显差异.土壤水分和温度受降雨影响,在不同的下垫面条件下表现出不同的变化.土壤CO_2日平均浓度在2 cm和10 cm处分别为1726和4481 ppm.2018年夏季土壤CO_2浓度随土壤体积含水量的变化而变化,但与土壤温度呈弱相关. 相似文献
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利用公益性行业（气象）科研专项项目＂藏东南地区复杂下垫面地气交换观测研究＂在藏东南地区进行的地气交换观测实验数据,分析典型晴天和阴天条件下不同下垫面能量过程的特征及其差异。结果表明：在典型晴空状态下,不同下垫面的地表净辐射均具有明显的日变化特征,在典型阴天的情况下,不同下垫面地表净辐射日均值显著减小;在典型晴空天气下,4种类型下垫面上潜热均随着净辐射的增加而表现为增加的趋势,在典型阴天的情况下,潜热通量明显比晴空天气小;不同下垫面感热通量的日变化存在显著的差异,不同下垫面感热的变化特征在典型晴空和阴天条件下的差异不明显;不同下垫面土壤热通量与净辐射的变化趋势基本一致,阴天夜晚土壤热流的交换与晴天夜晚的差异不大,四种下垫面土壤均存在能量损失,土壤处于降温状态。 相似文献
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采用生物-大气传输模式（BATS模型）模拟了淮河流域山丘区和平原区在1998年汛期的暴雨洪水过程,从陆地-大气间水量交换的角度揭示了径流量、土壤含水量、土壤质地、植被分布的内在联系。结果表明：对于山丘区和平原区而言,根系层土壤含水量、土壤质地以及土壤颜色的变化对径流量的影响具有相似性,但是敏感性不同;而山丘区和平原区深层土壤含水量和植被覆盖率变化对径流量影响的作用正好相反。这些结果显示,由于山丘区与平原区的不同气候和下垫面条件,而造成两者水文性质的差异性,反映了大气-水文之间关系与作用的不同特征。 相似文献
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陆面过程模式对土壤含水量初值的敏感性研究 总被引：30，自引：6，他引：24
利用IAP94陆面过程模式,采用淮河流域能量与水份循环试验(HUBEX)期间两种下垫面(森林和旱田)、不同季节(5月、8月和11月)的观测资料,研究了模式对土壤含水量初值的敏感性.结果表明:对于森林和旱田下垫面,当土壤含水量减少时,地表净辐射均略有减少,同时潜热通量减少而感热通量增加.另外,模式对土壤含水量初值的敏感性有较明显的季节差异,相对而言在晚春和夏季较强,而在秋季明显减弱.这说明春夏季节的土壤含水量初值在淮河流域区域气候的模拟和预测中尤其值得关注. 相似文献
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《高原气象》2015,(4)
利用2012年7-9月微气象蒸发观测实验的观测资料和陆面模式CLM4.0,对荒漠草原过渡带快速变化的陆面过程进行了单点数值模拟试验,通过比较模拟值与观测值来检验模式的模拟能力。结果表明:(1)CLM4.0模式能较好地模拟下垫面快速变化的辐射通量、湍流通量、土壤温度及土壤含水量的变化特征,但模拟值较观测值还存在一定偏差。在干旱及湿润地表状况下,CLM4.0模式模拟的反射辐射与观测值的偏差较小,而草地地表时模拟值较观测值偏高;CLM4.0模式较好地模拟了地表长波辐射的变化趋势,但是在正午和夜间偏差较大。(2)CLM4.0模式模拟的湍流通量与观测值之间的相关系数达0.85以上,但模拟值较观测值偏高。(3)CLM4.0模式模拟的土壤温度及含水量较观测值偏小,且对强降水引起的土壤含水量的变化过程的模拟性能较差。发展适用于干旱荒漠草原过渡带的土壤孔隙度参数化方案,进而通过改善土壤热导率、导水率的模拟有助于提高该类下垫面土壤温度及土壤含水量的模拟性能。 相似文献
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云检测中所使用的云检测阈值正确与否是关系到云检测精度的重要因素。该文利用1983年7月-2007年6月ISCCP数据对覆盖我国及周边区域不同云类云顶温度的年、日变化特征进行分析, 得到云顶温度的分布特征; 对晴空下垫面与最暖云云顶温度差随纬度分布特征、不同区域晴空下垫面及云顶温度与晴空地表温度差日变化特征进行分析, 这些特征及每3 h的晴空下垫面24年平均亮温作为云检测算法的背景场, 用以判识实时动态提取云检测阈值的合理性。个例分析表明:利用多年平均晴空下垫面温度及最暖云云顶温度与晴空下垫面温度之差, 可有效识别云检测阈值的合理性, 合理的阈值有助于提高连续多日被云覆盖及冰雪下垫面条件下的云检测精度。 相似文献
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黄土高原自然植被下垫面陆面过程参数研究 总被引：1，自引：1，他引：0
利用兰州大学半干旱气候与环境观测站的观测资料,分析了黄土高原自然植被下垫面陆面过程相关物理参数.研究了总体输送系数的不同季节平均日变化和频率分布特征,考察了地表粗糙度的变化趋势以及降水的影响.降水正常年份的总体粗糙度为0.009 m,偏干年份总体粗糙度为0.006 m,月平均粗糙度变化与正常年份相比较为平缓,降水通过增加植被覆盖和生长高度,使地表粗糙度增大.对总体输送系数与粗糙度以及总体理查森数的关系分别进行了讨论,在中性层结下黄土高原地区动力输送作用占主导地位,发现动量总体输送系数和奈曼流动沙丘下垫面很接近,而感热输送系数与戈壁下垫面接近.分析了反照率和太阳高度角以及土壤湿度的关系,并拟合得到以这两个物理量为因子的参数化公式.总体上,黄土高原自然植被下垫面的反照率比敦煌荒漠小,而大于长白山松林下垫面,这与3个地区植被覆盖和土壤质地的不同有关.通过对参数化公式模拟效果的检验,发现低太阳高度角下的反照率对土壤湿度和太阳高度角以外的其他因素敏感,而对应高太阳高度角的反照率受土壤湿度和太阳高度角的控制较强.最后,计算了土壤热传导率和热扩散率等土壤热力参数,相同湿度的热传导率比敦煌荒漠要大,并拟合得到热传导率以土壤湿度为自变量的参数化公式. 相似文献
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利用青藏高原北麓河观测站（退化高寒草甸）和玛曲观测站（高寒草原）2014年地面观测资料,通过组合分类法,对比分析了两类下垫面生长季土壤含水量、水汽压差和净辐射对地表能量分配的直接影响和间接影响,并且利用路径分析法研究了影响地表能量分配的关键气候因子。结果表明:北麓河站和玛曲站潜热占比（潜热通量与地表可利用能量的比值）对土壤含水量的响应分别处于土壤水分抑制阶段和能量抑制阶段。其中,北麓河站潜热占比在水汽压差较大时随土壤含水量增长较快,受净辐射的影响较小;而玛曲站潜热占比随土壤含水量的变化趋势受水汽压差和净辐射的影响均较小。北麓河站潜热占比随水汽压差的增大先减小后趋于不变,并且潜热占比对水汽压差的敏感性随土壤含水量的增大而减小;而玛曲站潜热占比随水汽压差的增大先增大后趋于不变,几乎不受土壤含水量和净辐射的影响。北麓河站和玛曲站潜热占比均随净辐射的增大趋于稳定,其稳定值分别与土壤含水量和水汽压差有关。路径分析结果显示,降水是影响北麓河站潜热占比的主要气候因子,而气温是影响玛曲站潜热占比的主要气候因子。 相似文献
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一个用于气候模式的简单冻土过程参数化方案的建立和检验 总被引：13，自引：0，他引：13
在NCAR／LSM的基础上，发展了一个简单的冻土过程参数化方案，并使用苏联6个站的水气象观测资料考察了耦合了新方案模式的气候效应。在新方案中，加入了对含冰量的求解和在相变过程中的能量变化;并使用Johanson的方案替代了模式中原有的土壤导热率的参数化方案，考虑了含冰量对土壤水热性质的影响。原模式和改进后模式的模拟结果的比较得到，冻土过程方案能够合理的模拟土壤列中的能量收支及水热性质随含冰量的变化。随着入渗的减少和径流的增加，春季的土壤湿度减小。因此，热通量的分配和土壤温度也产生了相应的变化。 相似文献
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利用位于季节冻土区的中国科学院那曲高寒气候环境观测研究站那曲/BJ观测点的野外观测数据,通过CLM4.5的单点模拟实验,分析评估了Luo土壤热导率参数化方案、Johansen土壤热导率参数化方案、Coté土壤热导率参数化方案和虚温参数化方案对土壤温、湿度的模拟能力,为将来选取最优的参数及参数化方案来更合理的模拟青藏高原土壤冻融过程为目的的工作提供依据。结果表明:(1)三种土壤热导率参数化方案模拟结果的土壤热传导率有明显差异,其中Coté方案的土壤热传导率最高,Luo方案的土壤热传导率最低。(2)三种热传导率方案均能合理地模拟出土壤温湿度的日变化趋势,Johansen方案对土壤温度年变化趋势模拟的更好,Coté方案对土壤温度模拟的数值较观测值偏离的更小,Luo方案对土壤湿度的模拟更好。(3)加入虚拟温度方程,并引入相变效率参数后,减少了模式对土壤湿度模拟的负偏差,Y-L方案在保持土壤温度较好模拟能力的基础上,能够进一步的提升土壤湿度的模拟能力。 相似文献
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Impact of the anomalous thawing in the Tibetan Plateau on summer precipitation in China and its mechanism 总被引：3，自引：0，他引：3
The impact of the anomalous thawing of frozen soil in the late spring on the summer precipitation in China and its possible mechanism are analyzed in the context of the frozen soil thawing date data of the 50 meteorological stations in the Tibetan Plateau, and the NCEP/NCAR monthly average reanalysis data.Results show that the thawing dates of the Tibetan Plateau gradually become earlier from 1980 to 1999,which is consistent with the trend of global warming in the 20th century. Because differences in the thermal capacity and conductivity between frozen and unfrozen soils are larger, changes in the freezing/thawing process of soil may change the physical properties of the underlying surface, thus affecting exchanges of sensible and latent heat between the ground surface and air. The thermal state change of the plateau ground surface must lead to the thermal anomalies of the atmosphere over and around the plateau, and then further to the anomalies of the general atmospheric circulation. A possible mechanism for the impact of the thawing of the plateau on summer (July) precipitation may be as follows. When the frozen soil thaws early (late) in the plateau, the thermal capacity of the ground surface is large (small), and the thermal conductivity is small (large), therefore, the thermal exchanges between the ground surface and the air are weak (strong). The small (large) ground surface sensible and latent heat fluxes lead to a weak (strong) South Asian high, a weak (strong) West Pacific subtropical high and a little to south (north) of its normal position. Correspondingly, the ascending motion is strengthened (weakened) and precipitationin creases (decreases) in South China, while in the middle and lower reaches of the Changjiang River, the ascending motion and precipitation show the opposite trend. 相似文献
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Soil is heterogeneous and has different thermal and hydraulic properties, causing varied behavior in heat and moisture transport. Therefore, soil has an important effect on land–atmosphere interactions. In this study, an improved soil parameterization scheme that considers gravel and organic matter in the soil was introduced into CLM4.5 (Community Land Model). By using data from the Zoige and Madoi sites on the Tibetan Plateau, the ability of the model to simultaneously simulate the duration of freeze–thaw periods, soil temperature, soil moisture, and surface energy during freeze–thaw processes, was validated. The results indicated that: (1) the new parameterization performed better in simulating the duration of the frozen, thawing, unfrozen, and freezing periods; (2) with the new scheme, the soil thermal conductivity values were decreased; (3) the new parameterization improved soil temperature simulation and effectively decreased cold biases; (4) the new parameterization scheme effectively decreased the dry biases of soil liquid water content during the freezing, completely frozen, and thawing periods, but increased the wet biases during the completely thawed period; and (5) the net radiation, latent heat flux, and soil surface heat flux of the Zoige and Madoi sites were much improved by the new organic matter and thermal conductivity parameterization. 相似文献
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H. H. Schomberg J. L. Steiner S. R. Evett A. P. Moulin 《Theoretical and Applied Climatology》1996,54(1-2):5-16
Summary The effectiveness of crop residues to protect the soil surface and reduce soil erosion decreases as residues decompose. The rate of residue decomposition is directly related to the temperature and moisture regimes of the residues. Predicting changes in residue mass, orientation, and soil cover requires the use of functions that relate changes in decomposition rates to changes in the temperature and water regimes. Temperature and water functions used in the residue decomposition submodel of the Wind Erosion Prediction System (WEPS) were evaluated for their effects on predictions of residue decomposition. A precipitation function (PC) was found to produce relatively more accurate estimates of decomposition than a near surface soil water content function (SWC) for describing water regime effects. The estimated accuracies of the two functions were similar when bias in the estimation was considered. Predictions made with PC had estimated accuracies of ± 11.4, 14.5, 13.5% for alfalfa, sorghum and wheat, respectively, while those made with SWC had estimated accuracies of ± 13.8, 16.2, and 16.9%, respectively. Three temperature functions were compared for use in predicting residue decomposition over a range of locations and crops. There was little difference between the temperature functions over all the locations but, for several locations, one function overpredicted decomposition more often than the other two functions. Accuracies ranged from ±4 to ±51% of the observed values. The highest values were obtained at one location, and all three temperature functions produced similar high values. Over most of the data, estimated accuracies were generally between ± 15 and ± 25%. The prediction intervals were similar to those observed for decomposition of surface-placed residues. This evaluation indicates that the temperature and water functions used in the WEPS decomposition submodel will give reasonable estimates of mass loss from surface residues using easy-to-obtain weather data.With 8 Figures 相似文献
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Pan Yongjie Lyu Shihua Li Suosuo Gao Yanhong Meng Xianhong Ao Yinhuan Wang Shujin 《Theoretical and Applied Climatology》2017,127(3-4):1011-1022
Soils containing gravel (particle size ≥2 mm) are widely distributed over the Qinghai–Tibet Plateau (QTP). Soil mixed with gravel has different thermal and hydrological properties compared with fine soil (particle size <2 mm) and thus has marked impacts on soil water and heat transfer. However, the most commonly used land models do not consider the effects of gravel. This paper reports the development of a new scheme that simulates the thermal and hydrological processes in soil containing gravel and its application in the QTP. The new scheme was implemented in version 4 of the Community Land Model, and experiments were conducted for two typical sites in the QTP. The results showed that (1) soil with gravel tends to reduce the water holding capacity and enhance the hydraulic conductivity and drainage; (2) the thermal conductivity increases with soil gravel content, and the response of the temperature of soil mixed with gravel to air temperature change is rapid; (3) the new scheme performs well in simulating the soil temperature and moisture—the mean biases of soil moisture between the simulation and observation reduced by 25–48 %, and the mean biases of soil temperature reduced by 9–25 %. Therefore, this scheme can successfully simulate the thermal and hydrological processes in soil with different levels of gravel content and is potentially applicable in land surface models.
相似文献19.
青藏高原复杂下垫面能量和水分循环季节变化特征分析 总被引：2，自引：2，他引：0
为深入认识青藏高原能量和水分循环季节变化,利用GSWP(Global Soil Wetness Project)、GLDAS(Global Land Data Assimilation System)、AMSR-E(Advance Microwave Scanning Radiometer-EOS)土壤湿度以及台站观测资料等多种数据,采用滑动t检验初步分析高原下垫面各物理量季节变化特征。结果表明:各物理量季节变化特征明显且联系密切。高原下垫面净短波辐射和感热通量在1月中旬显著开始增加,5~6月达到全年最高值。净长波辐射5月表现为高值,夏季表现为低值。地表潜热通量在1月显著开始增加,在夏季达到全年最高值。表层土壤3月开始输送热量到大气,9月大气开始向土壤表层传递热量;融雪3~5月加快,雪盖减少。降水和1 cm植被含水量在2月显著开始增加,1 cm土壤显著开始加湿,5~6月降水陡增,1 cm土壤湿度表现为峰值。1 cm植被含水量、植被蒸腾、总蒸散与降水在7~8月达全年最高值,1 cm土壤湿度在7月表出现为谷值,9月达全年第二峰值。10月下垫面温度转冷后,雪盖增加,土壤湿度逐渐减小。 相似文献