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1.
The turbulent heat flux was measured with two instruments simultaneously over the Baltic Sea by means of the eddy-correlation method. In one observational period, a small but noticeable divergence in heat flux was found, which may be explained by the advection of colder air. The parameterization of heat flux by the bulk method leads to a value for C
Hof 1 × 10–3. 相似文献
2.
The Bowen-ratio profile method for calculating total carbon dioxide, latent heat, and sensible heat flux density above a corn crop was used by measuring temperature, water vapor, and CO2 concentrations at several heights in the aerodynamic boundary layer of the crop. The ratio (α) of sensible heat flux density to carbon dioxide flux density as well as the Bowen ratio (β) were used in the computations. The two ratios, α and β were determined graphically from the slopes of linear plots of temperature vs CO2 concentration and vs water vapor. Each of the energy flux densities was computed from the two ratios and net radiation minus soil heat flux density. An analysis of probable error was performed on the Bowen-ratio profile method to evaluate the accuracy of the flux density estimates. Less than 10% error was found for latent heat flux density and less than 15% for carbon dioxide flux density under normal midday conditions for the instrumentation used. However, the carbon dioxide flux density error increased to over 40% when the sensible heat flux was small. 相似文献
3.
C. Jacovides P. Kerkides G. Papaioannou F. B. Smith 《Theoretical and Applied Climatology》1992,45(2):145-154
Summary Hourly lysimetric and micrometeorological data taken over a grass surface at the Meteorological Research Unit, Cardington U.K. have been analysed. A temperature difference and measurements of wind speed at only one height, combined with an independently estimated effective roughness length allowed sensible heat and momentum fluxes determination by the profile method on an hourly basis. The estimates are compared with direct measurements of sensible heat and friction velocity obtained by the eddy correlation method. The sensible and latent heat fluxes are also modelled by the resistance method. Equations based on the Monin—Obukhov similarity theory are used to account for stability effects through various forms of parameterization Aerodynamic and surface resistances, necessary for the Penman—Monteith equation are calculated from routinely measured meteorological data. The profile method for estimation of sensible heat flux and friction velocity is found to work excellently on the discussed daytime experimental data which correspond mainly to near neutral or slightly unstable conditions.Surface latent and sensible heat fluxes can also be described very well by the resistance method. A slightly better estimate of the sensible heat flux is achieved when stability corrections are taken into account. On the contrary Penman-Monteith equation for estimating latent heat flux is insensitive to adjustments for atmospheric stability.The comparison of the various methods leads to the establishment of empirical relationships which correlate various quantities such as soil heat flux, resistances, evapotranspiration etc. to routinely measured meteorological data.With 8 Figures 相似文献
4.
白洋淀水陆不均匀地区能量平衡特征分析 总被引：5，自引：1，他引：4
应用2005年9月在河北白洋淀地区进行的大气边界层综合观测实验资料, 对水陆不均匀地表条件下的白洋淀地区陆地的能量平衡特征进行了分析。结果表明: (1) 该地区存在能量不闭合现象。涡动相关法得到的感热、 潜热之和仅为有效能的75%, 其中涡动相关法得到的潜热通量为Bowen比法得到的潜热通量的70%, 而涡动相关法得到的感热通量为Bowen比法得到的感热通量的77% 。 (2) 地表潜热通量和感热通量随着净辐射的变化而变化。但潜热通量明显比感热通量大, 净辐射主要消耗于地表的水汽蒸发。 (3) 该地区白天的Bowen比平均在-0.4~0.4之间, 总体平均为0.131。受天气条件影响较大, 有明显的日变化, 午后15:00以后近地面层会出现逆温, Bowen比变为负值。 (4) 能量闭合程度有一定的日变化, 随着太阳高度角的增大而增大。 相似文献
5.
The bandpass eddy covariance method has been used to measure the turbulent flux of scalar quantities using a slow-responsescalar sensor. The method issimilar in principle to the traditional eddy correlation method but includes the estimation of high-frequency components of the flux on the basis of cospectral similarity in the atmospheric surface layer. In order to investigate the performance of the method, measurements of the water vapour flux over a forest with the bandpass eddy covariance method and the direct eddy correlation method were compared. The flux obtained by the bandpass eddy covariance method agreed with that by the eddy correlation method within ±20% for most cases, in spite of a rather slow sensor-response of the adopted hygrometer. This result supports its relevance to a long-term continuous operation, since a stable, low-maintenance,general-purpose sensor canbe utilized for scalar quantities. Oneweak point of the method isits difficulty in principle to measure the correct flux when the magnitude of the sensible heat flux is very small, because the method uses the sensible heat flux as a standard reference for the prediction of undetectable high-frequency components of the scalar flux. An advanced method is then presented to increase its robustness. In the new method, output signals from a slow-response sensor are corrected using empirical frequency-responsefunctions for the sensor,thereby extending the width of the bandpass frequency region where components of the flux are directly measured (not predicted). The advanced method produced correct fluxes for all cases including the cases of small sensible heat flux. The advanced bandpass eddy covariance method is thus appropriate for along-term measurement of the scalar fluxes. 相似文献
6.
青藏高原作为世界第三极,其热力强迫作用不仅对亚洲季风系统的发展和维持十分重要,也会对大气环流场产生深远影响。利用欧洲中期天气预报中心（ECMWF）的ERA-Interim中1979-2016年3-10月青藏高原及其周边地区的地表热通量月平均再分析资料,通过分析得出以下结论:3-5月青藏高原主体由感热占据,感热强度快速上升且呈西高东低的分布态势,潜热强度较小但随时间而增强。季风爆发后的6-8月,青藏高原感热强度减弱,潜热强度迅速增强且呈东高西低的分布特征。季风消退后的9-10月,感热与潜热强度相当,但感热呈现出西高东低的分布特征。过去38年,青藏高原地表感热总体呈现微弱下降趋势,潜热呈较弱上升趋势。青藏高原西部地区感热呈微弱下降趋势,潜热呈上升趋势。东部感热呈较为明显的下降趋势且近年来变化趋势增强,东部潜热通量则呈现较为明显的上升趋势,分析结论与近期全球变暖条件下青藏高原气候变暖变湿这一变化状况一致,通过对青藏高原地表热通量的变化分析为下一步运用第三次青藏高原大气科学试验所获资料分析青藏高原上空大气热源的变化以及地表加热场如何影响大气环流奠定基础。 相似文献
7.
青藏高原东部草甸下垫面涡旋相关观测数据的质量控制及评价研究 总被引：2，自引：1，他引：1
目前利用涡旋相关仪观测地表通量的方法已被广泛采用, 但由于涡旋相关法是建立在方程假设简化的基础上, 这对观测数据的质量提出了一定的要求, 所以对观测数据的处理及通量结果的质量状况分析就显得尤为重要。本文以理塘站2006年7月中到8月中的数据为例, 对其进行质量控制, 并将质量控制后的通量计算结果与原始值进行比较。质量控制后感热通量和潜热通量总和有所增长, 动量通量值则受质量控制影响较大。质量评价的结果为:动量通量、感热通量、潜热通量中高质量数据所占比例为68.2%、60.6%、63.3%。 相似文献
8.
南疆沙漠腹地大气边界层湍流通量特征的观测研究 总被引：4，自引：0，他引：4
利用新疆塔中站2006年4月、8月的三维风速。温度和水汽脉动资料,运用涡旋相关法计算得到了春、夏季塔中10m高度的动量、感热和潜热通量。结果表明,塔中地区地表热量输送以感热输送为主。春季每天的最大感热通量变化范围为120—320W·m^-2,月平均值为220W·m^-2;夏季最大感热通量的变化范围为140—340W·m^-2,月平均值为230W·m^-2。感热通量值在夜间为负,白天为正,符号的改变出现在日出、日落前后。夏季潜热通量最大值一般为20—60W·m^-2,平均值为27W·m^-2,潜热通量比感热通量小一个量级。春季动量通量的平均值为-0．063W·m^-2,夏季动量通量的平均值为-0．091W·m^-2。日变化规律比较明显,日出后,动量向下传输增大,在09-10时（地方时）出现一个最大值,随后动量向下传输并开始减小。 相似文献
9.
介绍了2004年在广州番禺进行的陆气相互作用观测试验。观测研究表明:新型的超声风温仪虽然带有雨滴防护沙网, 但雨滴对超声观测的误差影响显著, 尤其是对u, w方向。雨天情况下
10.
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
11.
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
12.
利用2008年7月兰州大学半干旱气候与环境观测(SACOL)站的观测资料,对比分析了地表土壤热通量的三种计算方法,即谐波法、温度预报校正法(TDEC法)以及结合自校正热通量板(HFP01SC)测量的温度积分法(ITHP法);进而分析了三种不同方法的计算结果对地表能量平衡的影响。比较5cm深度处谐波法和TDEC法的计算结果与HFP01SC的实测结果,三者的相位基本一致,相互之间均具有很好的线性关系;谐波法与TDEC法的计算值较为接近,但分别比HFP01SC的实测值偏大了2%和6%(主要发生在夜间)。对于地表的土壤热通量(G0),谐波法与TDEC法两者的计算结果仅偏差约1%;TDEC法与ITHP法的计算结果之间也具有很好的线性关系(R2=0.99),但偏差达到9%左右。相对于HFP01SC的实测结果,由谐波法和TDEC法计算的G0可将SACOL站的地表能量闭合率分别提高6%和7%左右;利用温度积分法将HFP01SC的实测结果校正到地表后,地表能量闭合率也提高了约6%。因此,在对涡动相关通量做了常规订正的情况下,当充分考虑了土壤热存储后,SACOL站的地表能量闭合率可提高6%～7%,达到82%～83%左右。 相似文献
13.
Jens Bange Peter Zittel Thomas Spieß Jörg Uhlenbrock Frank Beyrich 《Boundary-Layer Meteorology》2006,119(3):527-561
The low-level flight method (LLF) has been combined with linear inverse models (IM) resulting in an LLF+IM method for the determination of area-averaged turbulent surface fluxes. With this combination, the vertical divergences of the turbulent latent and sensible heat fluxes were calculated from horizontal flights. The statistical errors of the derived turbulent surface fluxes were significantly reduced. The LLF+IM method was tested both in numerical and field experiments. Large-eddy simulations (LES) were performed to compare ‘true’ flux profiles with ‘measurements’ of simulated flights in an idealised convective boundary layer. Small differences between the ‘true’ and the ‘measured’ fluxes were found, but the vertical flux divergences were correctly calculated by the LLF+IM method. The LLF+IM method was then applied to data collected during two flights with the Helipod, a turbulence probe carried by a helicopter, and with the research aircraft Do 128 in the LITFASS-98 field campaign. The derived surface fluxes were compared with results from eddy-covariance surface stations and with large-aperture scintillometer data. The comparison showed that the LLF+IM method worked well for the sensible heat flux at 77 and 200 m flight levels, and also for the latent heat flux at the lowest level. The model quality control indicated failures for the latent heat flux at the 200 m level (and higher), which were probably due to large moisture fluctuations that could not be modelled using linear assumptions. Finally the LLF+IM method was applied to more than twenty low-level flights from the LITFASS-2003 experiment. Comparison with aggregated surface flux data revealed good agreement for the sensible heat flux but larger discrepancies and a higher statistical uncertainty for the latent heat flux 相似文献
14.
利用2008年6月11～30日在金塔开展的"绿洲系统非均匀下垫面能量水分交换和边界层过程观测与理论研究"期间第一阶段戈壁下垫面大孔径闪烁仪(LAS)的观测资料,用混合对流方法和自由对流方法分别计算了戈壁感热通量。结果表明,对于利用LAS资料计算地表感热通量的方法中,混合对流方法相对于自由对流方法更加适用,且混合对流方法中Andreas给出的参数相对于DeBruin的参数更加适用于戈壁下垫面。此外,LAS测得的感热通量相对涡动相关方法的值较大,提高了地表能量闭合度。 相似文献
15.
Yaoming Ma Cunbo Han Lei Zhong Binbin Wang Zhikun Zhu Yongjie Wang Lang Zhang Chunchun Meng Chao Xu Pukar Man Amatya 《Theoretical and Applied Climatology》2014,117(3-4):643-652
In this study, a parameterization methodology based on Advanced Very High-Resolution Radiometer (AVHRR), Moderate Resolution Imaging Spectroradiometer (MODIS), and in situ data is proposed and tested for deriving the regional surface heating field, sensible heat flux, and latent heat flux over a heterogeneous landscape. In this case study, this method is applied to the whole Tibetan Plateau (TP) area. Four sets of AVHRR data and four sets of MODIS data (collected on 17 January 2003, 14 April 2003, 23 July 2003, and 16 October 2003) were used in this study to make comparisons between winter, spring, summer, and autumn values. The satellite-derived results were also validated using the “ground truth” as measured in the stations of CAMP/Tibet (Coordinated Enhanced Observing Period (CEOP) and Asia–Australia Monsoon Project on the Tibetan Plateau). The results show that the surface heating field, sensible heat flux, and latent heat flux in the four seasons across the TP are in close accordance with its land surface status. These parameters range widely due to the strongly contrasting surface features found within the TP region. Also, the estimated surface heating field, sensible heat flux, and latent heat flux all agree with the ground truth data, and usually, the absolute percentage difference between the two sets of data is less than 10 % at the validation stations. The AVHRR results were also in agreement with the MODIS data, with the latter usually displaying a higher level of accuracy. We have thus concluded that the proposed method was successful in retrieving surface heating field, sensible heat flux, and latent heat flux values using AVHRR, MODIS, and in situ data over the heterogeneous land surface of the TP. Shortcomings and possible further improvements in the method are also discussed. 相似文献
16.
利用位于青藏高原东侧理塘大气综合观测站2008年观测资料,分析了高寒草甸下垫面上地表通量的时间变化特征,确定了温度、水汽和CO2的归一化标准差在不稳定情况下随稳定度变化的通量方差关系,应用通量方差法对感热、潜热和CO2通量进行了计算,并与涡旋相关系统的观测结果进行了比较。结果表明：地表通量月平均日变化呈较为规则的日循环特征,季节变化特征也很明显,雨季（5-9月）潜热大于感热,干季则以感热为主,CO2通量以6-9月值最大。在不稳定条件下,温度、水汽和CO2的归一化标准差随稳定度的变化均满足-1/3规律,其通量方差相似性常数分别为1.2,1.4和0.9。通量方差法估算出的通量值与涡旋相关观测得到的通量值有较好的一致性,但感热通量的效果优于潜热通量和CO2通量。该方法高估了感热通量尤其是潜热通量,而低估了CO2通量。采用直接观测的感热通量值计算潜热通量和CO2通量可改善计算结果。 相似文献
17.
Summary The Bowen Ratio-Energy Balance (BREB) and the aerodynamic method were used to estimate turbulent fluxes of sensible and latent
heat flux over an irrigated agricultural area (IAA) and over two dry agricultural areas (DAA1 and DAA2). These turbulent fluxes
were analysed and particular attention paid to two specific areas. First, a quantitative analysis of sensible and latent heat
fluxes obtained by the BREB method was carried out, taking into account different soil type, vegetation and surface conditions.
The results showed that in IAA latent heat flux was higher than sensible heat flux, except in summer months, while in DAA1
and DAA2, sensible heat flux was higher except in the months when the vegetation was at the stage of maximum development.
Second, sensible and latent heat fluxes estimates from the BREB method were compared with those obtained from the aerodynamic
method. In this comparison factors such as soil type, soil vegetation cover, homogeneity or inhomogeneity of terrain and mesoscale
effects such as orography and wind patterns were taken into account. The results show that in conditions of light wind, the
two methods only concur if the condition of horizontal homogeniety is fulfilled. The influence of inhomogeneity seems to decrease
and agreement between methods improves, if the wind is stronger and the effects of meso and synoptic scales are predominant.
Received May 18, 1999/Revised March 15, 2000 相似文献
18.
高山草甸下垫面夏季近地层能量输送及微气象特征 总被引：8，自引：5，他引：3
利用青藏高原东坡理塘站2007年6～8月的观测资料, 分析了高原东坡草甸下垫面夏季近地层气象要素和湍流通量日变化特征, 并用涡动相关法估算地面的曳力系数。结果表明: 水平风速、 动量通量、 摩擦速度等均在下午最大, 早晨最小。二氧化碳浓度表现为早晚高、 中午低的日变化特征, 比湿的最大值出现在早晨。地表辐射、 热量平衡各分量最高值出现在中午, 最低值出现在早晨。地表反照率表现出早晚高中午低的 “U” 型分布, 日平均值为0.164。夏季地面热源强度在白天午后表现为强的热源, 在夜里表现为弱的冷、 热源交替出现。夏季近地层地气热量交换中, 感热输送作用小, 潜热输送占主要地位。 相似文献
19.
A new method for deduction of the sensible heat flux is validated with three sets of published SODAR （sound detection and ranging） data. Although the related expressions have previously been confirmed by the author with surface layer data, they have not yet been validated with observations from the boundary layer before this work. In the study, selected SODAR data are used to test the method for the convective boundary layer. The sensible heat flux （SHF） retrieved from SODAR data is found to decrease linearly with height in the mixed layer. The surface sensible heat fluxes derived from the deduced sensible heat flux profiles under convective conditions agree well with those measured by the eddy correlation method. The characteristics of SHF profiles deduced from SODAR data in different places reflect the background meteorology and terrain. The upper part of the SHF profile （SHFP） for a complicated terrain is found to have a different slope from the lower part. It is suggested that the former reflects the advective characteristic of turbulence in upwind topography. A similarity relationship for the estimation of SHFP in a well mixed layer with surface SHF and zero-heat-flux layer height is presented. 相似文献
20.
利用简化动力学近似分析黑河实验区的感热通量 总被引：3，自引：0，他引：3
本文利用简化动力学近似．运用统计和参数化两种方法分析了黑河实验区的感热通量．结果表明：不稳定条件下绿洲区的感热通量与近地面辐射温度(T3)和空气温度(Ta)之差符合幂定律方程；沙漠地区符合形式为H=f[u(T2-Ta)]的幂定律方程。利用从实验得到的热传输附加阻尼表示式kB^-1=0．2u(T2-Ta)用于对空气动力学阻尼(ra)的参数化，可适用于不同下垫面．并得到了比较满意的感热通量值．最后利用以上结果计算了实验区的潜热通量并做了比较分析。 相似文献