Improved representation of breaking wave energy dissipation in parametric wave transformation models     

J.M. Alsina  T.E. Baldock 《Coastal Engineering》2007

An improved formulation to describe breaking wave energy dissipation is presented and incorporated into a previous parametric cross-shore wave transformation model [Baldock, T.E., Holmes, P., Bunker, S., Van Weert, P., 1998. Cross-shore hydrodynamics within an unsaturated surf zone. Coastal Engineering 34, 173–196]. The new formulation accounts for a term in the bore dissipation equation neglected in some previous modelling, but which is shown to be important in the inner surf zone. The only free model parameter remains the choice of γ, the ratio of wave height to water depth at initial breaking, and a well-established standard parameter is used for all model runs. The proposed model is compared to three sets of experimental data and a previous version of the model which was extensively calibrated against field and laboratory data. The model is also compared to the widely used model presented by Thornton and Guza (1983) [Thornton, E.B., Guza, R.T., 1983. Transformation of wave height distribution. Journal of Geophysical Research 88 (No.C10), 5925–5938].  相似文献   

Kinetic Energy Variability in the North Indian Ocean Using a Numerical Model     

Aftab A. Can  Raj Kumar Sujit Basu 《Marine Geodesy》2002,25(1):175-186

The North Indian Ocean exhibits profound impact of variation in lower tropospheric winds. In the present study climatological monthly winds are used to force a nonlinear reduced gravity model of the North Indian Ocean to simulate climatological surface circulation and sea level anomaly for all 12 months of the year. The sea level anomalies agree reasonably well with satellite altimeter derived sea level anomalies. The model successfully simulates the varying eddy structure and current pattern of the North Indian Ocean. Finally, the kinetic energy variation in the North Indian Ocean with special reference to equatorial region and the boundaries is analyzed in detail.  相似文献   

黄海冬季环流的数值模拟   总被引：4，自引：1，他引：4  

刘兴泉 《海洋与湖沼》1996,27(5):546-555

在北黄海和渤海冬季环数值研究的基础上，利用其进一步改进的数值差分格式，对整个黄海的冬季环流进行了数值模拟。数模结果表明，改进的差分格式完全保持了计算海区的总能量和总质量守恒。就环流的总趋势而论，数据模拟结果与由资料所分析的结果几乎完全相同。  相似文献   

摄食水平对梭鱼的生长和能量收支的影响   总被引：16，自引：1，他引：16  

线薇薇  朱鑫华 《海洋与湖沼》2001,32(6):612-620

于 1 999年 8— 1 2月 ,在水温为 (2 4 .0± 0 .5 )℃ ,摄食水平分别为体重的 0 %、1 %、2 %、3 %、4%和饱食的条件下进行梭鱼的摄食 -生长实验。结果表明 ,梭鱼湿重、干重、蛋白质和能量的特定生长率 (SGR)与摄食水平呈直线关系 ,其转化效率与摄食水平的增加成正比 ;梭鱼的湿重、蛋白质、干重和能量的维持水平分别为体重的 1 .85 1、1 .85 3、2 .882和 2 .3 4 2 (% d) ;排粪率和排泄率随摄食水平的增加而增加 ,并呈直线关系。在最大摄食水平下 ,能量收支等式为 :1 0 0C =4.41F +1 1 .1 8U +47.0 6R +3 7.3 5G  相似文献   

Calculations of wave transformation across the surf zone     

Ching-Piao Tsai  Hong-Bin Chen  John R. -C. Hsu 《Ocean Engineering》2001,28(8)

The accuracy of predicting wave transformation in the nearshore is very important to wave hydrodynamics, sediment transport and design of coastal structures. An efficient numerical model based on the time-dependent mild-slope equation is presented in this paper for the estimation of wave deformation across the surf zone. This model incorporates an approximate nonlinear shoaling formula and an energy dissipation factor due to wave breaking to improve the accuracy of the calculation of wave height deformation prior to wave breaking and also in the surf zone. The model also computes the location of first wave breaking, wave recovery and second wave breaking, if physical condition permits. Good agreement is found upon comparison with experimental data over several one-dimensional beach profiles, including uniform slope, bar and step profiles.  相似文献   

Regional moments,energy levels,and a new discriminant     

Lian-She Zhao  Donald V. Helmberger 《Pure and Applied Geophysics》1996,146(2):281-304

Teleseismic observations of explosions tend to be richer in short-period energy than are earthquakes, thus the effectiveness of them _b M _s discriminant. At regional distances the same basic separation occurs for smaller events in terms ofM _L M ₀ (Woods et al., 1993) andm _b M ₀ (Patton andWalter, 1993). While these studies demonstrate the basic differences in excitation, they suffer in practical application because of the detailed information required in the retrieval ofM ₀ . In this paper, we introduce a new method of discrimination, based on the energy strength (M _E ) from broadband regional records that appears to be effective and efficient. In this method all events are processed as earthquakes, and explosions are distinguished by their stronger energy levels relative to their long-period amplitudes. Results from 29 events recorded by TERRAscope, sampling 15 explosions from NTS and 14 earthquakes from the southwestern United States, are represented, indicating complete separation (45 data points).M _L =3.6 is the smallest event examined to date but the method can probably be extended to even smaller levels in calibrated regions.  相似文献   

地热学向何处去   总被引：1，自引：0，他引：1  

汪集Yang 《地球科学进展》1992,7(3):1-8

Based on the State-of-the-Art of Geothermics both at home and abroad,the question of "Where to go, Geothermics" has been answered in this paper. Author suggested that the Geothermicsin the future should go to:1)the deep interior of the Earth,2) the continental area,3 ) the atmosphere,4)the energy problem,5) the mining areas, 6) the oil一gas fields and finally,7) to earthquake prediclion. With the increasing demand for energy and mineral resources and under the pressure of environmental and hazard problems, Geothermics is also being experienced a stage of revolution. There exist opportunity and challenge. We should use the opportunity and face the challenge optimistically for thefurther development of Geothermics in various aspects.  相似文献   

Estimating the components of the sensible heat budget of a tall forest canopy in complex terrain     

U. Moderow  C. Feigenwinter  C. Bernhofer 《Boundary-Layer Meteorology》2007,123(1):99-120

Ultrasonic wind measurements, sonic temperature and air temperature data at two heights in the advection experiment MORE II were used to establish a complete budget of sensible heat including vertical advection, horizontal advection and horizontal turbulent flux divergence. MORE II took place at the long-term Carbo-Europe IP site in Tharandt, Germany. During the growing period of 2003 three additional towers were established to measure all relevant parameters for an estimation of advective fluxes, primarily of CO₂. Additionally, in relation to other advection experiments, a calculation of the horizontal turbulent flux divergence is proposed and the relation of this flux to atmospheric stability and friction velocity is discussed. In order to obtain a complete budget, different scaling heights for horizontal advection and horizontal turbulent flux divergence are tested. It is shown that neglecting advective fluxes may lead to incorrect results. If advective fluxes are taken into account, the sensible heat budget based upon vertical turbulent flux and storage change only, is reduced by approximately 30%. Additional consideration of horizontal turbulent flux divergence would in turn add 5–10% to this sum (i.e., the sum of vertical turbulent flux plus storage change plus horizontal and vertical advection). In comparison with available energy horizontal advection is important at night whilst horizontal turbulent flux divergence is rather insignificant. Obviously, advective fluxes typically improve poor nighttime energy budget closure and might change ecosystem respiration fluxes considerably.  相似文献   

8807号登陆台风的数值研究：内核结构及能量水汽收支   总被引：2，自引：1，他引：2  

徐亚梅 《气象学报》2007,65(6):877-887

使用PSU/NCAR研制的非静力中尺度模式MM5对登陆后维持较久的典型个例8807号台风(Bill)进行了数值模拟。模拟采用了网格距分别为18和6 km的两重双向嵌套网格。通过给定初始涡旋和选择合适的物理过程,模式不仅比较好地模拟了Bill的强度变化过程,而且再现了风暴的移动轨迹,对降水量的模拟也相当成功。文中利用细网格的模拟结果,分析台风登陆前后的内核结构特征和能量水汽收支,揭示Bill登陆后维持较久的可能原因。分析表明,Bill台风登陆后出现了中低层的稳定度特别是湿稳定度显著加大、表面热通量和水汽通量明显减小、摩擦耗散的动能显著增加等不利于台风维持的特征。但是台风登陆后眼墙结构长时间维持,在登陆初欺眼墙区的上升气流乃至较登陆前更强;台风登陆后通过低层辐合获得了大量水汽,眼墙区强劲的上升运动将低层辐合的水汽向中上层输送,在眼墙附近凝结产生大量的非绝热加热;非绝热加热不仅增暖气柱、增加位能还影响位能向动能的转换,虽然台风登陆后陆面摩擦显著加大,但气压梯度力所做的正功足以补偿摩擦耗散的动能,因而Bill能在登陆后长时间维持。  相似文献   

浅谈适应气候条件的建筑设计策略   总被引：2，自引：0，他引：2  

廖雪萍 凌洪丘平珠  唐炳莉 《广西气象》2006,27(3):44-46,54

以广西一些城市地域特点的气候条件为背景，浅析建筑设计适应气候条件的一些思路和若干手法和策略。  相似文献