卫星SAR图像的海洋大气边界层特征参数的反演

针对中国南海ERS-2／SAR三维对流涡旋图像,分别利用Young的协方差方法和惯性子域方法,反演了对流海洋大气边界层高度、海洋大气边界层垂直对流尺度速度、表面浮力通量、Obukhov长度、稳定性校正后的海面风速和海面风速稳定性校正因子。结果表明,2种反演方法的结果符合较好,在一定程度上说明利用协方差方法和惯性子域方法从卫星SAR图像反演海洋大气边界层参数的有效性。     

On Algebraic Perturbations in the Atmospheric Boundary Layer

Izvestiya, Atmospheric and Oceanic Physics - A simple model for the development of submesoscale perturbations in the atmospheric boundary layer (ABL) is proposed. The growth of perturbations is...     

Helicity and Turbulence in the Atmospheric Boundary Layer

Izvestiya, Atmospheric and Oceanic Physics - Helicity is inherent in many circulating motions and structures in the atmospheric boundary layer (ABL), where it is continuously reproduced due to the...     

Determination of Vertical Refraction in the Atmospheric Boundary Layer

Izvestiya, Atmospheric and Oceanic Physics - Classical methods for determining vertical refraction have been developing for more than 300 years, but their accuracy does not correspond to the...     

Study on Hydrodynamic Characteristics of Wave Turbulent Bottom Boundary Layer Using A Large-Sized Wave Flume

China Ocean Engineering - Experimental studies were conducted in a super-large wave flume, aiming at uncovering the hydrodynamic characteristics involved in the turbulent wave boundary layer of...     

Using Small Unmanned Aerial Vehicles for Turbulence Measurements in the Atmosphere

Izvestiya, Atmospheric and Oceanic Physics - This paper demonstrates the possibility of using the telemetry of small unmanned aerial vehicles (UAVs) to monitor the state of atmospheric turbulence....     

A Simple Eddy Viscosity Model of Rough Turbulent Wave Boundary Layer

- A one-layer time-invariant eddy viscosity model is specified to develop a mathematical model for describing the essential features of the turbulent wave boundary layer over a rough bed. The functional form of the eddy viscosity is evaluated based on computational results from a two-equation turbulence model in which the eddy viscosity varies with time and space. The present eddy viscosity model simplifies much of the mathematical complexity in many existing models. Predictions from the present model have been compared with a wide range of experimental data. It is found that the eddy viscosity model adopted in the present study is physically reasonable.     

Using Unmanned Aerial Vehicles for Search and Prediction of Ore Mineralization

Izvestiya, Atmospheric and Oceanic Physics - This paper is dedicated to reviewing and analyzing domestic and foreign literature on the use of unmanned aerial vehicles to search and predict ore...     

Turbulent and Macro-turbulent Structures Developed in the Benthic Boundary Layer Downstream of Topographic Features

The characteristics and effects of large-scale flow structures developed in the benthic boundary layer downstream from large topographic features were analysed throughout a tidal cycle. The observed signature of the macro-turbulent features consisted of streamwise modules of low horizontal velocity and high suspended sediment concentration (SSC), alternating with modules of high horizontal velocity and low SSC. These modules extended 10 to 20 m streamwise and exceeded 1 m vertically, and are believed to be related to flow separation effects over large bedforms upstream of the deployment site. The macroscale flow modules intensified the ‘ burst-like ’ turbulent events and favoured sediment transport. ‘ Ejection-like ’ events were magnified during modules of decreasing horizontal velocity and increasing turbidity, whereas ‘ sweep-like ’ events were magnified during modules of increasing horizontal velocity and decreasing SSC. The enhanced turbidity of the macroscale modules may be the result of enhanced upward diffusion of sediment by ejection events, whereas the low-turbidity modules may be induced by increased downward transport of suspended sediment by sweep events. These hypotheses were supported by cross-spectral analysis performed on velocity and suspended sediment concentration time-series recorded at the site. An enhanced (negative) contribution of outward and inward interaction events to the Reynolds stress, compared to those reported in uniform BBLs, resulted in ‘ abnormally ’ low stress values.     

Organized Roll Circulation and Transport of Mineral Aerosols in the Atmospheric Boundary Layer

Izvestiya, Atmospheric and Oceanic Physics - An investigation into mesoscale roll circulation and its transport characteristics in the atmospheric boundary layer (ABL) is carried out. The case...     

海域无人机全景监视监测技术及其应用

为充分利用先进设备和技术,提高我国海域使用动态监管水平,文章介绍无人机全景技术及其作业流程,并分析大笔架山海域无人机全景监视监测实例。研究结果表明:目前全景图主要利用普通相机拍摄的照片经专业图像软件后期处理生成,在多个行业领域应用,结合无人机的利用可大大扩展视野,具有快速高效、安全可靠和操作简便等优势,但在测量、自动化和视距等方面仍存在局限性;无人机全景图作业主要包括方案制订、数据获取、数据处理和图像发布4个步骤;海域无人机全景监视监测工作的开展为大笔架山海域使用动态监管提供有力的数据支撑。     

Experience of Studying the Vertical Structure of an Urban Heat Island Based on Satellite Data

Izvestiya, Atmospheric and Oceanic Physics - The structure of an urban heat island in the large industrial centers of the European part of Russia is studied based on the MetOp-A and MetOp-B...     

Linear Approximations of the Second Turbulent Moments of the Atmospheric Convective Surface Layer in a Forced-Convection Sublayer

The Monin–Obukhov similarity theory for the convective surface layer distinguishes two limiting cases: a dynamic limit and a free-convection limit. The dynamic limit for the convective surface layer is defined as a flow with a logarithmic profile of wind and a zero buoyancy flux at the underlying surface. The free-convection limit is characterized by a zero wind speed and a positive buoyancy flux at the underlying surface. The limits of the generalized Monin–Obukhov similarity theory are able to describe the higher order turbulent moments. In this paper, it is assumed that the convective surface layer consists of two sublayers: the lower dynamic sublayer adjacent to the surface and the upper forced-convection sublayer. The turbulent moments can be approximated separately for each sublayer. Linear approximations are suggested for the turbulent moments of the vertical velocity and the potential temperature variance in the forced-convection sublayer. The first-order expansion terms of them correspond to the free-convection limits of the Monin–Obukhov theory under no-wind conditions. The second-order expansion terms describe profiles of the turbulent moments in under convective conditions with a moderate wind. A comparison between the proposed approximations and experimental data strongly suggests that the linear approximation is correct within a forced-convection range.     

On the Applicability of Similarity Theory for the Stable Atmospheric Boundary Layer over Complex Terrain

Micrometeorological measurements in the atmospheric boundary layer over a hilly forest terrain have been made on a meteorological tower at several levels from the forest canopy top to a height that exceeds the height of trees almost seven times. A semiempirical length scale depending on the local topography features and the underlying surface type has been proposed and calculated. This scale has been shown to allow the universal functions of the Monin–Obukhov similarity theory to be corrected for a stable atmospheric boundary layer over complex terrain without substantial modification when compared to the universal functions over a homogeneous surface with small roughness elements. This approach can be used to refine the methods for calculating turbulent momentum fluxes from profile measurements over spatially inhomogeneous landscapes.     

黄东海大气边界层高度季节变化特征及其成因

利用CFSR再分析资料,采用EOF的分析方法统计分析了黄东海边界层高度的季节变化特征,探讨了2个模态的分布型以及与之相联系的下垫面热通量和垂直环流,统计了ICOADS资料中近30a逐月低云发生频率和海雾发生频率,揭示了其与边界层高度分布特征的一致性。结果表明:盛行风的平流作用与下垫面特征相结合造成的低空稳定性的变化是黄东海边界层高度时间上夏季低、冬季高,空间上呈现东高西低、南高北低的重要因素。EOF分析中第一模态表现为整个黄东海区域具有一致性,主要是大尺度环流的影响;第二模态为春秋相反的2个分布型,与海洋锋、冷舌以及暖水团的季节变化有着密切关系。黄东海大气边界层高度的最大值出现时间以及其大小在空间上较为一致,而最小值以黄东海海洋锋为界,向北逐渐减小,以南差异性不大,出现时间上有较大的差异。,这主要由黄东海冷舌、暖水团以及海洋锋的季节变化所引起对边界层经向分布影响较大所引起的。春夏季节,南部(西部)低云发生频率高于北部(东部),海雾发生频率低于北部(东部);海雾高频区对应较低边界层高度,而低云高频区对应相对较高边界层高度。     

某无人水下航行器阻力特性数值模拟

基于FLUENT流体CFD软件,对带鳍舵布局的某无人水下航行器进行了阻力特性数值模拟.选择了合理入口边界条件、出口边界条件、压力与速度的耦合求解方法.数值模拟结果与风洞实验对比表明:该方法对无人水下航行器的阻力特性的预测精度较高,且对流场的显示更加详细、直观.所取得的研究成果对带鳍舵布局无人水下航行器的外形设计具有一定...     

Large-Eddy Simulation and Parameterization of Decaying Turbulence in the Evening Transition of the Atmospheric Boundary Layer

Izvestiya, Atmospheric and Oceanic Physics - This study presents the results of large-eddy simulation (LES) of the evening transition in the atmospheric boundary layer in the case of free...     

基于CFD的TBL脉动压力水下航行器流激噪声计算

高速航行时的水下航行器的水动力噪声问题一直尤为突出,水动力噪声分为流体脉动压力直接辐射声与流激噪声,流激噪声是结构表面受到湍流脉动压力引起结构振动产生的噪声。由于湍流扰动的随机性,表面脉动压力时空不均,在计算流激噪声时需要统计分析方法的介入。湍流边界层脉动压力的计算方法主要包括传统的半经验公式法计算和 CFD 流场分析计算,将二者相结合对流激噪声进行预报,在流场仿真中提取出频率波数谱预测模型所需的参数,分别使用有限元法和统计能量法代入并计算,对比结果与理论经验公式方法得到的结果,二者的噪声结果较为吻合。     

The Effect of Internal Gravity Waves on Fluctuations in Meteorological Parameters of the Atmospheric Boundary Layer

Variations in the intensity of turbulence during wave activity in the stable atmospheric boundary layer over a homogeneous steppe surface have been analyzed. Eight wave activity episodes recorded with a Doppler sodar in August 2015 at the Tsimlyansk Scientific Station of the Obukhov Institute of Atmospheric Physics have been studied. These episodes include seven trains of Kelvin–Helmholtz waves and one train of buoyancy waves. Variations in the rms deviation of the vertical wind-velocity component, the temperature structure parameter, and vertical heat and momentum fluxes have been estimated for each episode of wave activity. It has been found that Kelvin–Helmholtz waves slightly affect the intensity of turbulence, while buoyancy waves cause the temperature structure parameter and the vertical fluxes to increase by more than an order of magnitude.     

Structure of the Wave Bottom Boundary Layer over Smooth and Rough Bottoms

The comparison of six well-known models of the wave bottom boundary layer shows that they are identical in the case of a smooth bottom but exhibit serious differences for the other types of conditions. The thickness of the wave bottom boundary layer and the coefficient of vertical diffusion of momentum are studied by using the relations of the k-ε-model. The validity of these estimates is checked by comparing the measured and computed values of the friction velocity. This comparison demonstrates fairly good agreement between the results characterized by a coefficient of correlation equal to 0.851. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 54–67, November–December, 2005.