南京夏季城郊湍流统计特性及湍流通量对比分析

利用2010年南京夏季城市热岛三维结构试验中的湍流观测资料,对南京市委党校和南京信息工程大学观测场2个观测点的湍流统计量和湍流通量进行了对比分析。结果表明：城市平均风速大于郊区;城郊2地的湍流强度都呈现出Ix〉Iy〉Iz的趋势,水平方向上的湍强城郊相差不大,而垂直方向上,郊区的Iz要明显低于城市;城、郊的风速归一化标准差σu/u＊、σv/u＊、σw/u＊都符合MoninObukhov相似理论的＂1/3＂定律,城市的垂直风速归一化标准差大于郊区,而水平方向上的风速归一化标准差则明显小于其他下垫面;郊区风速归一化标准差与常熟农田的拟合结果较为相似,而城市风速归一化标准差与长白山森林的拟合结果更为接近;夏季城市以感热通量为主,而郊区湍流能量的输送以潜热通量为主,且城市的湍流热通量受太阳辐射的影响更大。     

重庆地区近地面层湍流谱特征分析

利用１９８９年１２月－１９９０年１月重庆地区的观测资料，计算了一般天气条件下和雾中的湍流谱。结果表明，重庆地区中性和不稳定的条件下，湍谱的峰值频率比平坦地形大，峰值区较窄。在夜间静力稳定条件下，湍谱的低频部分能量突然增大。也揭示了雾中湍流说的一些特性。     

SPECTRAL CHARACTERISTICS OF SURFACE-LAYER TURBULENCE OVER THE SUBURBS OF TIANJIN

The paper computed the spectra of velocity and temperature,and the cospectra of velocity and temperature by theobservational data of July,1990 in the suburbs of Tianjin.The results show that the characteristics of the atmosphericturbulence spectra over the suburbs are basically in accordance with some typical results over the flat terrain.But thescale,on which turbulence can satisfy the isotropic condition,over the suburbs is larger than over the flat terrain.Thespectrum peak frequency range is a bit narrower.The feature of the spectrum range in low frequency(LF)is out ofaccordance with that of the flat terrain either.     

SPECTRAL CHARACTERISTICS OF SURFACE-LAYER TURBULENCE OVER THE SUBURBS OF TIANJIN*

The paper computed the spectra of velocity and temperature,and the cospectra of velocity and temperature by the observational data of July,1990 in the suburbs of Tianjin.The results show that the characteristics of the atmospheric turbulence spectra over the suburbs are basically in accordance with some typical results over the flat terrain.But the scale,on which turbulence can satisfy the isotropic condition,over the suburbs is larger than over the flat terrain.The spectrum peak frequency range is a bit narrower.The feature of the spectrum range in low frequency(LF) is out of accordance with that of the flat terrain either.     

边界层急流型重力波——飞机颠簸的一种形成机制

采用线性化的Boussinesq流体边界层绝热流动方程，比较一维边界层急流型重力波的垂直运动量级，讨论边界层急流型重力波中的湍流发展，认为边界层急流型重力波是造成边界层飞机颠簸的一种机制。     

边界层急流型重力波─-飞机颠簸的一种形成机制

采用线性化的Boussinesq流体边界层绝热流动方程,比较一维边界层急流型重力波的垂直运动量级,讨论边界层急流型重力波中的湍流发展,认为边界层急流型重力波是造成边界层飞机颠簸的一种机制。     

河谷城市小风条件下的近地层湍流特征

利用兰州城市和郊区皋兰县冬季同期的湍流观测资料,分析了城市和郊区的湍流强度、脉动速度标准差和湍流的欧拉时间积分尺度等湍流特征量,并与其他地区的湍流观测量进行了对比,从而揭示了兰州河谷城市小风条件下的大气湍流特征。     

TURBULENCE STRUCTURE AND TRANSFER CHARACTERISTICS IN THE SURFACE LAYER OF HEIFE GOBI AREA

Based on the HEIFE 1988 and 1990 pilot observations,an analysis on the turbulence structure of Gobi surfacelayer,mainly on the similarity formulations of wind and temperature variances,the spectra and cospectracharacteristics,is presented.The phenomenon of downward water vapor flux over Gobi desert in daytime is confirmedin both observations,this and the well-known‘oasis effect’are two sides of a local mesoscale circulation.     

南沙海域近海层大气湍流结构及输送特征研究

本文根据南沙群岛渚碧礁的一次大气湍流观测资料，分析研究南沙海域的湍流热通量输送、方差相似性、风速各分量谱、温度谱及各湍流通量协谱等大气湍流结构和输送特征，并与陆地下垫面上的结果作了比较，得到了一些有关南沙海域大气湍流输送及湍流结构的新认识。     

ATMOSPHERIC TURBULENCE STRUCTURE AND SPECTRAL CHARACTERISTICS AT NEAR SURFACE LAYER ON TROPICAL COASTS

By use of an observational experiment at the village of Tianwei, Haikou, Hainan province in 1990,characteristic turbulence values such as velocity component spectra and turbulence intensity are studied.The data were mostly obtained in cloudy condition, so that the stability parameter (L) and thermal flux (wt) did not vary diurnally while the turbulent energy and mean-temperature did. The basic characteristics of turbulence spectra are similar to those with fine weather, hems close to local isotropy in the inertial subrange. The velocity spectra agree with the law of "-2/3 th power"in Kolmogrov's similarity theory. The relationship between turbulent intensity of components δ_i/U (i=u,v,w) and stability Z/L is studied follow ins the Monim-Obukhov(M-O) similarity theory. It is shown that the two observe the law of "1/3 th power", though the turbulent intensity and energy are generally larger than those on the flat underlying topography.     

城市冠层中湍流运动的统计特征

对１９９７ 年夏天和冬天北京湍流运动的各种统计特征量进行了初步的统计分析。结果表明,城市冠层中湍流运动的各种统计特征量与平坦下垫面条件下边界层湍流运动的相比, 有不同的地方也有相似的地方; 无论白天还是夜晚, 垂直方向的湍流强度和湍流脉动风速标准差均小于水平方向的, 水平方向的相应湍流特征量则总是接近相等; 城市冠层中湍流脉动强度和标准差几乎均大于平坦下垫面边界层的; 平均风速ｕ≥１ ｍ ／ｓ 时的湍流统计特征量与ｕ＜ １ ｍ ／ｓ 时的有所不同; 城市冠层的阻力系数较大, 可达００６２５,Ｐａｎｏｆｓｋｙ 等提出的公式σｗ ／ｕ＊ ＝ １３ （１－ ３ｚ／Ｌ）１／３在城市冠层中并不适用。     

湍流不同尺度间的相互作用

湍流是由各种不同尺度的涡旋构成的。从整体上讲,存在Ｋｏｌｍｏｇｏｒｏｖ导得的惯性区结构函数的２／３次方定律和能谱的－５／３次方定律。这种幂律相关的湍流是由每种尺度上指数相关的局部相似的Ｂｒｏｗｎ运动所构成,从而从理论上解释了不同尺度之间的相互作用以及湍流系数Ｋ随尺度变化的规律,初步论证了大气不同层结下湍流系数的差别。结果对研究大气、海洋不同尺度间的相互作用有重要意义。     

中南地区航空器空中颠簸指数适用分析

利用ERA Interim再分析资料和2015—2019年中南地区航空器空中报告，对比分析7个指数在中南地区空中颠簸的适用效果，结果表明：①不同指数有无颠簸之间的值域重合率，Brown指数最低，其次是Ellrod1和Ellrod2，能够从指数值判断颠簸的强弱及存在与否，空报率较低；MOS CAT和L P指数值域重合率过高，容易造成较高的空报。②Ellrod1、Ellrod2和Brown计算的颠簸区与空中报告的位置对应最好，Dutton和HTG表现不稳定，MOS CAT和L P指数计算范围偏大，适用性较差。不同指数计算侧重点不同，当热力因素占主导时，HTG指数计算效果较好。     

The Characteristics of Turbulence Structure and Transfer over the Middle Area of the Tibetan Plateau

In this paper, turbulent data obtained from the Damxung site during the Secondary Tibetan Plateau Science Experiment (TIPEX) in 1998 are used to study the characteristics of the turbulent spectra, turbulence transport, and the dissipation rates of turbulent kinetic energy, temperature variance, and humidity variance in the middle area of the Tibetan Plateau. The turbulent spectra of wind velocity, potential temperature, and humidity satisfy the-2/3 power law in the high frequency range. Horizontal transportation of heat and water vapor is negligible compared with vertical transportation under strong unstable conditions, and as the stability parameter z/L increases (where z is the observational height, and L is the Monin Obukhov length), horizontal transportation becomes dominant under near-neutral, neutral, and stable conditions. The non-dimensional temperature and humidity variances are 20% less than the temperature and humidity gradient variances. These deficits appear to increase as the absolute stability parameter increases. Moreover, the effects of turbulence transportation and pressure variance exist throughout the entire stability region.     

The Theoretical Model of Atmospheric Turbulence Spectrum in Surface Layer

It is shown that the slope of energy spectrum obtained from the velocity solution of Kdv-Burgers equation lies between -5/3 and -2 in the dilogarithmic coordinates paper. The spectrum is very close to one of Kolmogorov’s isotropic turbulence and Frisch’s intermittent turbulence in inertial region. In this paper, the Kdv-Burgers equation to describe atmospheric boundary layer turbulence is obtained. In the equation, the 1 / Re, corresponds to dissipative coefficient v, to dispersive coefficient β, then (v/ 2β)2 corresponds to .We prove that the wave number corresponding to maximum energy spectrum decreases with the decrease of stability (i.e., the increase of in eddy-containing region. And the spectrim amplitude decreases with the increase of (i.e., the decrease of stability). These results are consistent with actual turbulence spectrum of atmospheric surface layer from turbulence data.     

A STUDY OF 1.5-ORDER CLOSURE TURBULENCE MODEL

Based on turbulence theory,a 1.5-order closure turbulence model is established.The model incorporating with theground surface energy budget equation is constructed by means of a vertical one-dimensional(1-D)40-levelgrid-mesh.The numerical results reveal the 24-h evolution of the clear planetary boundary layer comparing with theWangara boundary layer data of days 33—34.The model also takes into account some physical processes of radiativetransfer and baroclinicity,revealing some important characteristics observed in the boundary layer,especially for theevolution of the mixed layer and low-level jet.The calculated results are in good agreement with the observational data.On the other hand,we also run the high-resolution model of the planetary boundary layer in the Mesoscale Model Ver-sion 4(MM4)with the same physical processes and initial conditions.The results show that the high-resolution modelcan not reveal those important characteristics as the 1.5-order closure model did.In general,it is shown that the 1.5-or-der closure turbulence model based on turbulence theory is better in rationality and reality.     

松林冠层大气湍流结构观测研究

为了更好地了解大气与物质和能量交换，用二层三维超声风速温度仪测量了重庆市郊松林风速和温度脉动值。采样速率为每秒１次和１１次，数字量记录。计算了湍流动最通量和热通量的日变化，以及湍流风速的统计量和功率谱。结果表明，冠层上动量通量向下传输，而冠层内大多向上传输；冠层内湍流风速ｕ的三阶矩平均值大于零，ｗ的小于零；冠层上无因次湍流风速分量ｕ，ｗ标准差和无因次湍流动能耗散率与局地Ｍｏｎｉｎ－Ｏｂｕｋｈｏｖ长     

云南安宁市辐射雾大气扩散参数研究

利用三向风标探测资料，分析了安宁县辐射雾中的扩散参数，结果表明：平均风速对水平风向脉动标准差起着重要作用，是影响水平湍流扩散的关键因子；雾中的横向和铅直方向扩散参数分别相当于ＰａｓｑｕｉｌｌＢ类和Ｄ类稳定度下的扩散参数，表明在辐射雾出现期间，虽然铅直方向上的扩散能力不强，但有较强的水平扩散能力。     

植被冠层湍流代数应力模式

从植被冠层湍流时空平均雷诺应力方程出发，根据植被冠层内有关参数化的准则，建立了湍流代数应力模式，并用玉米和小麦两种作物地的实测资料对模式进行了验证。     

Application of a Large-Eddy Simulation Database to Optimisation of First-Order Closures for Neutral and Stably Stratified Boundary Layers

Large-eddy simulation (LES) is a well-established numerical technique, resolving the most energetic turbulent fluctuations in the planetary boundary layer. By averaging these fluctuations, high-quality profiles of mean quantities and turbulence statistics can be obtained in experiments with well-defined initial and boundary conditions. Hence, LES data can be beneficial for assessment and optimisation of turbulence closure schemes. A database of 80 LES runs (DATABASE64) for neutral and stably stratified planetary boundary layers (PBLs) is applied in this study to optimize first-order turbulence closure (FOC). Approximations for the mixing length scale and stability correction functions have been made to minimise a relative root-mean-square error over the entire database. New stability functions have correct asymptotes describing regimes of strong and weak mixing found in theoretical approaches, atmospheric observations and LES. The correct asymptotes exclude the need for a critical Richardson number in the FOC formulation. Further, we analysed the FOC quality as functions of the integral PBL stability and the vertical model resolution. We show that the FOC is never perfect because the turbulence in the upper half of the PBL is not generated by the local vertical gradients. Accordingly, the parameterised and LES-based fluxes decorrelate in the upper PBL. With this imperfection in mind, we show that there is no systematic quality deterioration of the FOC in the strongly stable PBL provided that the vertical model resolution is better than 10 levels within the PBL. In agreement with previous studies, we found that the quality improves slowly with the vertical resolution refinement, though it is generally wise not to overstretch the mesh in the lowest 500 m of the atmosphere where the observed, simulated and theoretically predicted stably stratified PBL is mostly located. The submission to a special issue of the “Boundary-Layer Meteorology” devoted to the NATO advanced research workshop “Atmospheric Boundary Layers: Modelling and Applications for Environmental Security”.