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青藏高原总体输送系数的特征 总被引：17，自引：1，他引：17
利用中日亚洲季风机制合作研究计划设在西藏的 4个自动气象站（AWS）获得的5a多（199年7月～1998年12月）时次密集、观测连续的近地层梯度资料,以最小二乘法确定出相应站点各季节的地表粗糙度,并应用廓线-通量法计算了4站逐日的总体输送系数,分析了其随时间的变化特征。结果表明:青藏高原动量输送系数的多年平均值为3.53×10-3～4.99×10-3,热量输送系数为4.67×10-3～6.73×10-3,并且两种输送系数都存在明显的日变化和季节变化,部分站点还存在较明显的年际变化。另外,还讨论了总体输送系数与近地层大气层结稳定度、地表粗糙度以及地面风速等因子的关系,初步建立了可用常规气象站地面观测资料计算青藏高原总体输送系数的拟合公式。 相似文献
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黄土高原半干旱草地近地层湍流温湿特征及总体输送系数 总被引：3，自引：0，他引：3
利用兰州大学半干旱气候与环境观测站(简称SACOL站)2008年夏季晴天近地层湍流观测资料,分析了SACOL站近地层湍流温、湿统计特征,确定了大气动力学和热力学粗糙度长度,讨论了总体输送系数随大气稳定度的变化规律。结果表明,大气层结不稳定条件下,无量纲温度和比湿脉动方差与稳定度Z/L之间均满足-1/3次规律;大气层结稳定条件下,温湿脉动方差总体趋势是随大气稳定度增加而减小。水汽通量全天大于零,最大值为0.063 g·m-2·s-1,地表日平均蒸发量为1.9 mm。中性条件下,黄土高原半干旱草地动力学粗糙度长度为6.6×10-3m,热力学粗糙度为1.85×10-5m。大气层结不稳定条件下,CD平均值为4.4×10-3,CH平均值为3.9×10-3;中性条件下,CD和CH平均值分别为4.2×10-3和2.8×10-3;层结稳定条件下,CD平均值为3.1×10-3,CH平均值为2.1×10-3,表明总体输送系数随稳定度的增大而减小。 相似文献
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陇中黄土高原植被覆盖和裸露下垫面地表通量和总体输送系数研究 总被引：3，自引：4，他引：3
通过对陇中黄土高原地区地表观测资料的分析,研究了该地区地表能量收支各项的平均日变化、小麦不同生长阶段的热通量日变化、总体输送系数平均日变化及其与稳定度的关系。结果表明:该地区白天潜热通量在净辐射通量的分配中所占的份额最大,其次为感热通量,土壤热通量最小;随着小麦的生长,潜热通量在净辐射通量的分配中所占的份额增加,感热通量则呈下降趋势,波文比呈下降趋势;在10m高度处,在小麦地动量总体输送系数Cd的平均值为6.03×10-3,感热总体输送系数Ch的平均值为3.40×10-3;在裸地,动量总体输送系数Cd的平均值为5.18×10-3,感热总体输送系数Ch的平均值为4.08×10-3。在同一观测高度上,Cd小麦>Cd裸地,Ch小麦相似文献
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利用在甘肃酒泉金塔地区进行的"绿洲系统能量与水分循环过程观测与数值研究"野外试验2005年5月16~21日的加强期观测资料,计算并分析了鼎新戈壁下垫面地表辐射平衡、地表能量平衡、地表空气动力学粗糙度、地表反射率以及动量、热量总体输送系数等物理量的变化特征,得到了鼎新戈壁下垫面近地层能量输送及微气象特征:(1)在5月份晴天天气下,太阳辐射各分量表现出了标准的地表辐射平衡的日循环形态,总辐射峰值可达1000 W.m-2以上;净辐射峰值达到526 W.m-2。(2)能量平衡各项都具有明显的日变化规律;白天感热通量最大值可达到400 W.m-2,潜热通量比感热通量小两个量级,地热流量峰值可达100 W.m-2以上;在下午和夜间存在负的水汽输送现象。(3)在中性条件下:z0=1.44×10-3m,CDN=2.1×10-3,CHN=1.8×10-3。(4)5月份地表反射率为0.217,反射率日分布大致呈"U"型。 相似文献
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用变分方法估算淮河流域总体输送系数 总被引：13，自引：3，他引：10
利用2001年6～7月间在安徽肥西的边界层观测资料,利用变分方法计算地面动量通量和感热通量,进而分别估算该处动量总体输送系数和感热总体输送系数。用变分方法计算的地面粗糙度为0.03m。在中性条件下,10m高处平均动量总体输送系数和感热总体输送系数分别为4.83×10-3和3.81×10-3,比值是1.27。总体输送系数具有明显的日变化特征,中午时段最大,夜晚最小;总体输送系数与大气稳定度存在明显关联,文中给出它们之间的拟合关系式;随着高度的增加总体输送系数减少,但减少幅度逐渐变小。 相似文献
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陆面上总体输送系数的特征 总被引：7，自引：4，他引：7
利用气象铁塔的风、温梯度资料，对陆面上近地层湍流拖曳系数ＣＤ和总体输送系数ＣＨ（或ＣＥ）的大小和日变化规律进行研究。发现陆面上较粗糙的地表，ＣＤ和ＣＨ可以比海面上大一个量级左右。而且存在着明显的日变化。它们对地表面动力粗糙度变化的反应较敏感。本工作为气候及大气环流模式研究中陆面参数化过程提供了重要依据。 相似文献
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In climate and weather prediction models the near-surface turbulent fluxes of heat and momentum and related transfer coefficients are usually parametrized on the basis of Monin–Obukhov similarity theory (MOST). To avoid iteration, required for the numerical solution of the MOST equations, many models apply parametrizations of the transfer coefficients based on an approach relating these coefficients to the bulk Richardson number \(Ri_{b}\). However, the parametrizations that are presently used in most climate models are valid only for weaker stability and larger surface roughnesses than those documented during the Surface Heat Budget of the Arctic Ocean campaign (SHEBA). The latter delivered a well-accepted set of turbulence data in the stable surface layer over polar sea-ice. Using stability functions based on the SHEBA data, we solve the MOST equations applying a new semi-analytic approach that results in transfer coefficients as a function of \(Ri_{b}\) and roughness lengths for momentum and heat. It is shown that the new coefficients reproduce the coefficients obtained by the numerical iterative method with a good accuracy in the most relevant range of stability and roughness lengths. For small \(Ri_{b}\), the new bulk transfer coefficients are similar to the traditional coefficients, but for large \(Ri_{b}\) they are much smaller than currently used coefficients. Finally, a possible adjustment of the latter and the implementation of the new proposed parametrizations in models are discussed. 相似文献
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A Measure of Inhomogeneity of the Land Surface and Parametrization of Turbulent Fluxes under Natural Conditions 总被引：1，自引：0，他引：1
Summary The effects of surface heterogeneity and nonstationarity on turbulent fluxes are parametrized by introducing an additional
roughness length that corrects for deviations from Stationarity and Horizontal Homogeneity (SHH). Using data from the experiments
of FIFE, KUREX, TARTEX and SADE, a relationship was detected between the underestimation of turbulent fluxes (the lack of
balance in the surface energy budget) and terrain inhomogeneity.
Based on the assumption that the parametrization obtained from these data is applicable for complex terrain surfaces in general,
the paper presents some simple relationships for surface turbulent fluxes, bulk transfer coefficients, and roughness lengths.
Received August 8, 1997 Revised March 9, 1998 相似文献
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万齐林 《热带气象学报(英文版)》2000,6(2):219-224
Derivation of bulk transport coefficients helps solving land surface processes. A similarity-based method for determining the turbulent transfer (including the flux exchange, the vertical distribution of wind and potential temperature) in the atmospheric surface layer is presented. Comparisons with iterative schemes (Businger, 1971) are given to demonstrate the advantages of the calculation methods. 相似文献
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A new surface-flux parameterization is presented and its impact on climate simulations with the Canadian Centre for Climate Modelling and Analysis (CCCMA) general circulation model (GCM) is discussed. The parameterization is based on the Monin-Obukhov similarity theory using well established flux-profile relationships for the unstable conditions. However, recently proposed new relationships are used in stable conditions. The new formulation allows different roughness lengths for heat and momentum, and gives transfer coefficients that are in agreement with Monin-Obukhov similarity theory. It also includes a parameterization for the free-convective boundary layer, which often occurs over warm surfaces within light winds. In circumstances where the surface layer is not neutrally stratified the proposed flux parameterization yields surface transfer coefficients that are different from those resulting from the standard surface flux formulation used in the GCM. The most marked effects of implementing the new formulation in the GCM are found over land and adjacent oceanic regions in winter where significant differences are found in the surface heat and moisture fluxes and surface temperatures. 相似文献
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Some evaluations of drag and bulk transfer coefficients over water bodies of different sizes 总被引：1，自引：0，他引：1
B. B. Hicks 《Boundary-Layer Meteorology》1972,3(2):201-213
Three recent experiments allow evaluation of the bulk transfer coefficients for momentum, water vapour and sensible heat over water bodies of different sizes. As part of a study of evaporation rates from a swamp, measurements of latent and sensible heat fluxes were made over Lake Wyangan in southern N.S.W., Australia. This lake is of several kilometers diameter. In a later experiment, Reynolds stress and sensible heat transfer were measured from a natural-gas platform standing in Bass Strait, south of mainland Australia. The most recent experiment involved the direct measurement of each of these turbulent fluxes from a fixed tower erected in Lake Michigan, U.S.A.Perhaps the most important of the results is the finding that drag coefficients measured over Bass Strait are not significantly different from those over Lake Michigan, despite the obvious differences in depth, fetch, and hence surface wave structure. At both locations, drag coefficients are found to increase slightly with increasing wind speed, while at low wind speeds they are not significantly different from those corresponding to aerodynamic smoothness.Near-neutral bulk transfer coefficients for sensible heat and for water vapour are found to be similar. An average value of about 1.4 × 10–3 is obtained.It is emphasized that stability effects should be considered in any discussion of drag coefficients or bulk transfer coefficients. Large errors can result if near-neutrality is incorrectly assumed. 相似文献
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Determination of the Drag Coefficient over the Tibetan Plateau 总被引：7，自引：0，他引：7
Li Guoping Duan Tingyang Wan Jun Gong Yuanf Shigenori Haginoy Chen Longxun Li Weiliang 《大气科学进展》1996,13(4):511-518
In this paper,a preliminary study is given on the drag (i.e.bulk transfer for momentum) coefficient,on the basis of data from four sets of AWS in Tibet during the first observational year from July 1993 to July 1994 according to China Japan Asian Monsoon Cooperative Research Program.The results show that the drag coefficient over the Tibetan Plateau is 3.3 to 4.4×103.In addition,monthly and diurnal variations of drag coefficient and the relationship among the drag coefficients and the bulk Richardson number,surface roughness length and wind speed at 10 m height are discussed in detail. 相似文献