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利用兰州大学半干旱气候与环境观测站(Semi-Arid Climate and Environment Observatory of Lanzhou University,SACOL)湍流观测资料,分析了二次坐标旋转(double rotation,DR)、平面拟合(planar fit,PF)和分风区平面拟合(fetch planar fit,FPF)在复杂地形上的适用性,总结出一套适用于SACOL的总体湍流特征参数化方案.经过超声虚温订正、坐标旋转、空气密度脉动订正以及平稳性检验、总体湍流特征检验、总体质量分级处理,摩擦速度(u*)、感热通量、潜热通量、CO_2通量高质量数据所占比例分别为45%~62%、66%~68%、62%~65%、52%~54%.采用DR得到的高质量数据比例与采用PF相比,u*提高了17%,后三种通量略降低2%~3%.PF和FPF两种结果的差别主要体现在u*上,只考虑主导风向数据DR得到的u*质量仍最好.综合兼顾数据质量和计算工作量,在复杂地形上处理湍流观测资料的最优坐标旋转方法是DR. 相似文献
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We propose a two-dimensional Lagrangian analytical solution for relating source strength and concentration profiles within
and above a plant canopy. The new solution describes passive scalar dispersion under conditions of local advection through
a fetch correction function in a one-dimensional Lagrangian analytical dispersion model. The model is capable of predicting
absolute concentration profiles of passive scalars for different fetches for situations in which the reference concentration
is known or the background concentration is available. Tests of the model showed good agreement with measurements from field
and wind-tunnel experiments. 相似文献
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Gerard Caudal 《Boundary-Layer Meteorology》1998,86(1):29-45
Donelan and Pierson have proposed a semiphysical model of the equilibrium sea wave spectrum, based upon a parameterization of wave growth and dissipation terms. Their model is applicable for fully developed seas only. In the framework of Donelan and Pierson's approach, this paper explores the dependence of the equilibrium spectrum upon wave age. To this end, we examine how the dissipation through wave breaking is expected to vary with wave age, according to the approach proposed by Longuet-Higgins in 1969. The constraint imposed by Longuet-Higgins' theory requires an increase of the equilibrium spectrum F(k,0) in the wind direction with increasing inverse wave age U/Cp. This is in accordance with Banner's empirically deduced statement that F(k,0) is proportional to (U/Cp)0.5 in the equilibrium range. Our inferred F(k,0) tends to increase more or less linearly with U/Cp (we find F(k,0) proportional to 1 + 0.25(U/Cp - 0.83), rather than through a power law. If a power law is fitted we obtain F(k,0) approximately proportional to (U/Cp)0.35 for the range 0.83 < U/Cp > 5. Finally, the roughness length of the air-sea interface is inferred from our modelled spectrum through integration of the form drag over wave number under rough conditions. This shows a wave age dependence that is compatible with measurements of wind stress performed in the field at various wave ages. 相似文献
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C. Lafon J. Piazzola P. Forget O. Le Calve S. Despiau 《Boundary-Layer Meteorology》2004,111(2):339-360
The whitecap coverage generated by breaking waves plays a major role in the transfer of heat, momentum, water vapour and particles at the air-sea interface. The sea surface covered by whitecaps strongly depends on both the wind and the wave-field characteristics. In particular, in coastal zones, the variations of the whitecap fraction, commonly noted W, differ from open ocean conditions, due to fetch effects, wave-current interactions, bottom influence and irregular coastlines affecting both the wind properties and the wave development. We present an analysis of the whitecap-fraction variations using experimental data acquired during FETCH (Flux, Etat de mer, et Télédétection en Condition de fetcH variable), an experimental campaign that took place in the Gulf of Lion off the French Mediterranean coast in 1998. The data include various conditions of wave development associated with fetch and unsteady effects. The whitecap fraction W was measured using an original image processing technique applied to sea surface photography. Specific relationships between the whitecap fraction and both atmospheric and oceanic parameters are investigated, which confirm the suitability of the friction velocity for modelling W. However, W has also been parameterised using wave-parameter dependent relationships, which is of interest for very short fetches. 相似文献
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南沙海区风浪分析与计算 总被引：3，自引：0，他引：3
根据南沙海区风浪实测资料,阐述了南沙海区波高的分布规律。应用相关分析法,通过多元回归计算,得出波要素与风速、风时之间的关系。对波高、波周期的相互关系作了统计分析并利用永署礁海洋观测站1990年1～7月的实测资料对计算结果作了验证。结果表明,南沙海区波高、波周期的计算值与实测值基本吻合。 相似文献
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《Sedimentology》2018,65(2):461-491
Gravelly beach ridges, which are formed solely by swash processes, may accurately reflect past wave conditions. The thickness (or height) of a gravelly beach ridge approximately equals the height of wave inundation, which is the sum of the surge and wave run‐up. Their ancient counterparts, if well‐preserved and identified, can be used to estimate palaeowave conditions, which can later be converted to palaeowind intensities based on wind–wave relationships. A technique is described for estimating the palaeowind speed in this paper, which is referred to as the gravelly beach‐ridge thickness technique. By comparing these estimates with instrumental wind records obtained at a modern lake, Qinghai Lake in north‐western China, the beach‐ridge thickness technique is shown to be useful for estimating the average wind speed (V avg). When applying this method to ancient fetch‐limited basins, five parameters are necessary: (i) the thickness of the isolated gravelly beach ridge; (ii) the average depth of the water body; (iii) the palaeofetch; (iv) the angle between the palaeowind direction and the normal to the shoreline; and (v) the particle size. This technique was applied to an ancient example in the Eocene Dongying Depression, located in eastern China. The results indicate that the average wind speed of the northern wind ranged between 2·27 m sec−1 and 8·36 m sec−1 from 45·0 Ma to 42·0 Ma, and displayed a generally decreasing trend that included early strengthening followed by weakening and later strengthening during this period. The beach‐ridge thickness technique provides a new perspective on delineating palaeowind conditions and can be applied to ancient fetch‐limited basins with gravelly beach ridges worldwide. Generally, if a water body is sufficiently large (fetch exceeding 40 km), deep (average depth exceeding 10 m) and waves (or winds) are determined to approach the shoreline with high angles (angle of incidence <35°), then the calculation errors will be small to negligible. 相似文献
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Footprint Analysis: A Closed Analytical Solution Based On Height-Dependent Profiles Of Wind Speed And Eddy Viscosity 总被引：5，自引：0，他引：5
Based on the theoretical background of existing models for the crosswind-integrated footprint, a new model is presented, which, in contrast to the existing models, describes the normalized footprint by a closed analytical formula. This was made possible by using well-known power profiles for wind speed and eddy viscosity instead of Monin–Obukhov based profiles at a certain stage of model development. However, the major difference between the new model and the existing models is that the so-called shape parameter of vertical plume dispersion, a function of upwind distance in the existing models, is set constant in the new model in order to circumvent a formal inconsistency found in the derivation of the existing models. Due to this inconsistency, the existing models do not generally satisfy the fundamental condition that the cumulative normalized footprint must approach unity for the upwind distance tending towards infinity. 相似文献