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Advances in Atmospheric Sciences 2009年第3期26卷 577-584页

作者：张占海周明煜 Sharon ZHONG Donald H. LENSCHOW Qing WANG Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136 State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 Department of Geography Michigan State University East LansingMI 48824-111USA National Center for Atmospheric Research BoulderCO 80307USA Department of Meteorology Naval Postgraduate SchoolMontereyCA 93943USA

A set of new parameterizations for the friction velocity and temperature scale over gently sloped terrain and in calm synoptic conditions are theoretically derived. The friction velocity is found to be proportional to the product of the square root of the total accumulated heating in the boundary layer and the sinusoidal function of the slope angle, while the temperature scale is proportional to the product of the boundary layer depth, the sinusoidal function of the slope angle and the potential temperature gradient in the free atmosphere. Using the new friction velocity parameterization, together with a parameterization of eddy diffusivity and an initial potential temperature profile around sunrise, an improved parameterization for the thermally induced upslope flow profile is derived by solving the Prandtl equations. The upslope flow profile is found to be simply proportional to the friction velocity.

关键词： friction velocity temperature scale slope terrain flux-profile relationship upslope flow

Test of the Louis scheme and COARE algorithm for friction velocity in different wind-sea/swell regimes

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Acta Oceanologica Sinica 2005年第4期24卷 20-28页

作者： GAO Zhiqiu HU Wen LIU Shaomin Chinese Academy of Meteorological Sciences Beijingl00081 China Jiangsu Province Key Laboratory of Meteorological Disaster and Environmental Variation Nanjing 210044 China Anhui Meteorological Bureau Hefei 230061 China State Key Laboratory of Remote Sensing Science School of Geography Beijing Normal University Beijing 100875 China

The Louis scheme and the COARE algorithm （version 3.0） are tested against eddy covariance and inertial dissipation methods for friction velocity estimates in different wind-sea/swell regimes. Atmospheric forcing data, tabulated by Donelan et al. （1997.J Phys Oceanog, 27：2087-2099）, were collected from a mast on the foredeck of a SWATH （small water-plane area, twin hull） ship in deep sea off the State of Virginia during the surface wave dynamics experiment. These data are representative of low to moderate wind regimes. The aerodynamic roughness length is determined by using the Charnock relationship. The intercomparison shows that the Louis scheme and the COARE algorithm underestimate the friction velocity by 6% and 3% respectively under pure wind sea conditions, 15% and 13% respectively under cross swell conditions, and 21% and 17% respectively under counter swell conditions. The analysis shows that these underestimations were caused by the method chosen to determine the aerodynamic roughness length because it significantly underestimates the aerodynamic roughness length. It is especially true under the cross swell and counter swell conditions.

关键词： Louis scheme friction velocity sea surface

Wave-Dependence of friction velocity, Roughness Length, and Drag Coefficient over Coastal and Open Water Surfaces by Using Three Databases

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Advances in Atmospheric Sciences 2009年第5期26卷 887-894页

作者：高志球 Qing WANG 周明煜 State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 Department of Meteorology Naval Postgraduate School Monterey California USA Key Laboratory for Polar Science Polar Research Institute of China Shanghai 200136

The parameterization of friction velocity, roughness length, and the drag coefficient over coastal zones and open water surfaces enables us to better understand the physical processes of air-water interaction. In context of measurements from the Humidity Exchange over the Sea Main Experiment （HEXMAX）, we recently proposed wave-parameter dependent approaches to sea surface friction velocity and the aerodynamic roughness by using the dimensional analysis method. To extend the application of these approaches to a range of natural surface conditions, the present study is to assess this approach by using both coastal shallow （RASEX） and open water surface measurements （Lake Ontario and Grand Banks ERS-1 SAR） where wind speeds were greater than 6.44 m s-1. friction velocities, the surface aerodynamic roughness, and the neutral drag coefficient estimated by these approaches under moderate wind conditions were compared with the measurements mentioned above. Results showed that the coefficients in these approaches for coastal shallow water surface differ from those for open water surfaces, and that the aerodynamic roughness length in terms of wave age or significant wave height should be treated differently for coastal shallow and open water surfaces.

关键词： sea surface roughness wave parameter friction velocity parameterization

Numerical analysis of supersonic jet flow and dust transport induced by air ingress in a fusion reactor

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Nuclear Science and Techniques 2021年第7期32卷 72-82页

作者： Bu-Er Wang Shi-Chao Zhang Zhen Wang Jiang-Tao Jia Zhi-Bin Chen Institute of Nuclear Energy Safety Technology Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China

During a loss of vacuum accident(LOVA),the air ingress into a vacuum vessel(VV)may lead to radioactive dust resuspension,migration,and even explosion,thereby posing a great threat to the safe operation of future fusion reactors;thus,it is crucial to understand the flow characteristics and radioactive dust transport behavior induced by ***,only a few studies have identified the characteristics of the highly under-expanded jet flow at a scale of milliseconds during ***,the occurrence and behavior of a Mach disk is yet to be captured in existing *** this study,we used a more advanced model with a finer mesh and adaptive mesh strategies to capture the Mach disk in a VV during *** detail,a computational fluid dynamics–discrete phase model one-way coupled multiphase approach was established using the computational fluid dynamics code ANSYS FLUENT and applied to the analysis during the first seconds of *** results showed that air ingress into the VV behaved like a highly free under-expanded jet at the initial stage and Mach disk was formed at~6 ***,the flow field dramatically changed at the position of the Mach *** jet core before the Mach disk had a maximum velocity of~8 Mach with the corresponding lowest static pressure(~100 Pa)and temperature(few tens of K).The friction velocities in the lower part of the VV,which is an area of concern due to dust deposition,were generally larger than 15 m/s near the inlet ***,the crude prediction of the particle trajectories demonstrated the spiral trajectories of the dust following the air ***,this study provided a basis for further safety analysis and accident prevention related to dust transport and explosion in future fusion reactors.

关键词： Supersonic jet Radioactive dust Loss of vacuum accident Mach disk friction velocity

Dependence of Estimating Whitecap Coverage on Currents and Swells

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Journal of Ocean University of China 2021年第3期20卷 512-520页

作者： LIU Min YANG Bailin JIA Nan ZOU Zhongshui Ocean College Hebei Agriculture UniversityQinhuangdao 066000China School of Resources and Materials Northeastern University at QinhuangdaoQinhuangdao 066004China PLA Information Engineering University Zhengzhou 450001China School of Marine Science Sun Yat-Sen UniversityZhuhai 519082China

The shipboard measurements of whitecap coverage(W)and the meteorological and oceanographic information from two cruises in the South China Sea and Western Pacific are explored for estimating *** study aims at evaluating how to im-prove the parameterizations of W while considering the effects of currents and swells on wave *** indeed affect W in a way that winds with following currents can decrease W,whereas winds with opposing currents can increase ***,10-m wind speed over sea surface(U_(10))is calibrated by subtracting the current velocity from U_(10) when the propagating directions of winds and currents are *** contrast,when the direction is opposite,U_(10) is calibrated by adding the parallel velocity com-ponent of the opposing current to U_(10).The power fits of W dependence on the U_(10)-related parameters of U_(10),friction velocity,wind sea Reynolds number in terms of this calibrated-U_(10) obtain better results than those directly fitted to U_(10).Different from the effect of currents on W,wind blowing along the crest line of swells may contribute to the increase in *** conclusions suggest that U_(10) should be calibrated first before parameterizing W in areas with a strong current or some swell-dominant areas.

关键词： whitecap coverage currents friction velocity wind sea Reynolds number swells

AN APPROACH TO SEPARATING THE CURRENT velocity IN ESTUARINE AND COASTAL WATERS

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Journal of Hydrodynamics 2009年第4期21卷 512-519页

作者： NI Zhi-hui SONG Zhi-yao WU Li-chun State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Ocean College Hohai University Nanj ing 210098 China Key Laboratory of Virtual Geographic Environment Ministry of Education Nanjing Normal University Nanjing 210097 China Chongqing Education College Chongqing 400067 China

In the near-shore waters, the actual flow is mainly induced by tide, wind and salinity, and the river water runoff should also be included as a component in the estuary waters. The interactions among these major components are very complicated. Many approaches were proposed to study isolated tide and wind-driven currents or run-off based on the measured velocity, with all its components taken as a whole. In this article, firstly, based on the actual hydrodynamic characteristics of estuarine and coastal waters, an approach is proposed to separate the measured velocity by considering the theoretical current velocity profiles and using the least squares method. The vertical structures of tidal, wind-driven currents, density current and runoff can be obtained as well as their proportions in the measured velocity. Then, this approach is applied to the analysis of velocity data obtained in the North Branch of Yangtze River estuary and of laboratory test data. The results are found to be satisfactory. Finally, this approach is used to separate the measured velocity in the South Branch of Yangtze River estuary, to determine not only the bed friction velocity and roughness height, but also the surface wind stress, and to estimate the wind velocity data above the water surface. The results show that this method is simple in principle, practical in use, and reasonable in obtained results. So it can be used to effectively analyze the field data.

关键词： tide wind-driven current density current river water runoff friction velocity roughness height velocity separation

Size distribution of PM_(20) observed to the north of the Tibetan Plateau

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Journal of Mountain Science 2021年第2期18卷 367-376页

作者： ZHOU Cheng-long YANG Fan HUO Wen MAMTIMIN Ali YANG Xing-hua Institute of Desert Meteorology China Meteorological AdministrationUrumqi 830002China Taklimakan Desert Meteorology Field Experiment Station China Meteorological AdministrationUrumqi 830002China

The size distribution of airborne dust particles is an important parameter in the measurement of dust emissions due to wind erosion,and a quantitative and accurate description is *** regarding the size distribution of airborne dust particles are currently lacking in Tibetan Plateau(TP).This study aims to obtain a dust particle size distribution and compare the difference in spatial distribution at a field site(FS)and two urban observation sites(Minfeng and Hetian),in the north of the TP,under the condition of the dust-days and *** observation data was collected from 5 July to 4 August,*** mass concentration of dust(PM20)was measured with a 10-stage quartz crystal microbalance cascade *** results suggested that 91.9%of the particles were less than 1.4μm on clear-days,and particles of d≥1.4μm increased to 27.2%with the occurrence of the dust *** than 80%of the airborne dust particles were less than 1.4μm for each friction *** proportion of d0.7μm was the greatest at 0.5 m on *** urban observation,with the occurrence of dust events,the concentration of a particle size greater than 2.5μm increased most significantly in Minfeng,while the concentration of a particle size less than 0.7μm increased most significantly in ***,the proportion of particles with d1.4μm had the most obvious difference among these three sites.

关键词： Dust day Clear day friction velocity Field Urban Coefficient variation

Parameterization of Wave Breaking Probability and Whitecap Coverage

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China Ocean Engineering 2006年第3期20卷 411-418页

作者：李晶于定勇刘华兴 College of Engineering Ocean University of China Qingdao 266071 China

The model for whitecap coverage and wave breaking probability are parameterized by the dimensionless wind fetch X^-. This paper aims at replacing X^- with other parameters such as the average wave period T^-, wind speed U10 or wave age ξ in order to improve the suitability and convenience of the model for application. First, W and B are expressed in terms of T^- and U10, which are relatively easy to measure in the field. Further, U10 is replaced with the friction velocity U. by use of the empirical relationship. As wave age has been widely used to parameterize spectral models of ocean waves and air-sea fluxes, W and B are then expressed as a simple function of wave age, respectively. The new forms of the model obtained are W= 1 - Ф（3.02ξ0＂76） and B = exp（ - 4.54ξ^1.52） . The two forms are mere applicable in pracrice, since ξ is relatively easy to measure or determine from wave and wind records. Comparisons between these expressions and data collected from published literature are made and agreement is fairly good.

关键词： whitecap coverage wave breaking probability friction velocity wave age

Study on the Log-Linear velocity Profile of Near-Bed Tidal Currentin Estuarine and Coastal Waters

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China Ocean Engineering 2006年第4期20卷 573-584页

作者：宋志尧严以新郝嘉凌孔俊张红贵 State Key Laboratory of Hydrology Water Resources and Hydraulic Engineering Ocean College Hohai University

Many observed data show that the near-bed tidal velocity profile deviates from the usual logarithmic law. The amount of deviation may not be large, but it results in large errors when the logarithmic velocity profile is used to calculate the bed roughness height and friction velocity （or shear stress）. Based on their investigation, Kuo et al. （1996） indicate that the deviation amplitude may exceed 100%. On the basis of fluid dynamic principle, the profile of the near-bed tidal velocity in estuarine and coastal waters is established by introducing Prandtl＇ s mixing length theory and Von Kannan selfsimilarity theory. By the fitting and calculation of the near-bed velocity profde data observed in the west Solent, England, the results are compared with those of the usual logarithmic model, and it is shown that the present near-bed tidal velocity profile model has such advantages as higher fitting precision, and better inner consistency between the roughness height and friction velocity. The calculated roughness height and friction velocity are closer to reality. The conclusions are validated that the logarithmic model underestimates the roughness height and friction velocity during tidal acceleration and overestimates them during tidal deceleration.

关键词： tidal velocity profile logarithmic law roughness height friction velocity

Wind speed scaling and the drag coefficient

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Acta Oceanologica Sinica 2005年第4期24卷 29-42页

作者： WEN Fan GAO Zhiyi WU Ziku Lü Hongmin Laboratory of Physical Oceanography Ocean University of China Qingdao 266003 China

Wind speed scaling in similarity law in wind-generated waves and the drag coefficient are studied. In analyzing the data in the wind wave channel, it is found that the u＊ scaling greatly reduces the scatter in the U10 scaling. The u＊ scaling has much less scatter than the scaling using other wind speeds. The friction velocity seems to play a distinctive role in wave growth. The result is important in the applications of the similarity law and in wave modeling. In theory it gives an insight into the mechanism of wind wave interaction. It is found that wave steepness is important in influencing the drag coefficient. The variability of the coefficients in the currently widely used drag form can be explained by the differences in wave steepness in the observations. A drag coefficient model with wind speed and wave steepness as parameters is proposed. An explanation for Kahma＇s result that the u, scaling does not reduce the scatter in the U10 scaling is given.

关键词： friction velocity scaling scatter drag coefficient wave steepness