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1.
《高原气象》2021,40(2):374-383
利用小兴安岭南麓五营地区涡动相关系统的观测资料,分析不同大气稳定度条件的湍流速度谱、温度谱、湿度谱、协谱及局地各向同性特征。结果表明:三维速度(u、v、w)谱和垂直速度(w)与水平纵向速度(u)、温度(θ)的协谱(uw、θw)的谱峰均随稳定度的增加而向高频端移动。湍流速度(u、v、w)谱、温度(θ)谱和湿度(q)谱在惯性副区均满足-2/3定律。uw协谱、θw协谱和垂直速度(w)与湿度(q)的协谱(qw)在惯性副区并不完全遵循-4/3定律,尤其是uw协谱的拟合斜率更接近-1。水平方向湍流谱峰波长范围为130～1820 m,垂直范围为49～113 m。温度谱谱峰波长范围为149～260 m,湿度谱谱峰波长范围为198～455 m。uw协谱谱峰波长范围为228～455 m,θw协谱谱峰波长范围为172～260 m,qw协谱谱峰波长范围为172～346 m。v谱在惯性副区基本满足局地各向同性,w谱在惯性副区不满足局地各向同性,可能与森林下垫面对垂直方向湍流大涡的破碎作用有关。 相似文献
2.
大气近地层湍流能谱特征的再分析 总被引：5，自引：1，他引：4
根据Kolmogorov局地均匀性湍流假设,大气近地层湍流能谱在惯性副区符合"-5/3律".但是作者通过翻阅大量文献以及实测资料分析发现,大气近地层湍流能谱符合"-5/3律"的频率范围比较狭窄,而用幂函数+指数函数形式"fS(f)∝F-ae-bf"拟合更恰当一些,这种能谱函数形式是连续时间混沌系统所特有的.利用HEIHE实验湍流观测资料分析结果表明,对于径向风分量,a＝0.447,b＝0.228;切向风分量:a＝0.489,b＝0.190;垂直风分量:a＝0.551,b＝0.124;温度:a＝0.588,b＝0.123. 相似文献
3.
根据Kolmogorov局地均匀性湍流假设，大气近地层湍流能谱在惯性副区符合“－5／3律”。但是作者通过翻阅大量文献以及实测资料分析发现，大气近地层湍流能谱符合“－5／3律”的频率范围比较狭窄，而用幂函数＋指数函数形式“fS(f)∝f^-ae^-bf”拟合更恰当一些，这种能谱函数形式是连续时间混沌系统所特有的。利用HEIHE实验湍流观测资料分析结果表明，对于径向风分量，a=0.447,b=0.228；切向风分量：a=0.489,b=0.190；垂直风分量：a=0.551,b=0.124；温度：a=0.588,b=0.123。 相似文献
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根据黑河地区地气相互作用实验研究(HEIFE)1988年POP和1990年PIOP实验的观测资料,分析了戈壁地区近地层大气的湍流结构,主要是风速分量和温度方差的相似关系,以及各有关量的功率谱和湍流通量的协谱。1988年POP期间发现的戈壁近地层大气中白天经常出现的水汽由上而下输送等特殊现象,在1990年PIOP中得到进一步的验证。文中分析了有关物理机制,认为这一现象和众所周知的“绿洲效应”是戈壁-绿洲这一地区性中尺度环流影响的两个侧面。 相似文献
8.
郑新倩 《沙漠与绿洲气象(新疆气象)》2017,11(5):63-69
利用2013年6月巴丹吉林沙漠拐子湖地区流沙下垫面的陆气通量观测资料,计算并分析了该研究区不同大气稳定层结条件下的湍流速度各分量谱和温度谱及湍流的局地各向同性特征。结果表明:该研究区风速各分量的湍流强度随平均风速的增加而逐渐减小,当平均风速2 m/s时,风速各分量的湍流强度逐渐稳定且基本限定在0.5以内。在不同大气稳定度下,湍流速度和温度能谱曲线在惯性副区内逐渐有合并趋势且遵循Kolmogorov提出的-2/3定律,速度各分量谱在高频段均满足各向同性且符合低频限制理论。随着稳定度的增加,风速分量的能谱曲线逐渐降低且向高频端移动,风速分量和温度能谱对应的谱峰长度则逐渐减小。该研究区水平湍流尺度范围为9.0~600 m,垂直湍流谱峰波长为10.79~75 m。该结果介于草地和森林下垫面之间,与塔克拉玛干沙漠腹地的试验结果较为接近。 相似文献
9.
登陆台风近地层湍流特征观测分析 总被引：16，自引：1，他引：15
在对多个登陆台风实地观测的基础上,选取出较有代表性的实验观测个例:“黄蜂”、“杜鹃”和“黑格比”3个登陆台风,分析探讨在登陆台风的中心、靠近中心位置的强烈影响区域和台风外围环流影响地区近地层湍流特征,以期对登陆台风的边界层湍流过程有所认识。观测资料分析显示,在登陆台风的中心及其强烈影响的区域:(1)风速和湍流强度均有强烈的变化;(2)水平湍流积分尺度明显增大,越靠近中心位置,增大越明显,而垂直方向没有明显变化;(3)在湍流谱的低频和高频区,湍能均可增大1~2个量级,其中垂直方向湍能增大的幅度略小于水平方向;(4)湍谱在惯性子区u,v,w3个方向的分布均不满足-5/3次方律,存在较大偏移,而在台风外围环流影响区和无台风影响时,则无上述的4个特征。 相似文献
10.
城市冠层上下大气湍流特征分析 总被引：2，自引：0，他引：2
利用兰州市榆中县城市冠层架设的3台涡动相关仪(EC)观测大气湍流资料,分析了城市冠层上下不同下垫面湍流通量和不同风向范围内湍流动能变化特征,之后对城市冠层上下3台EC观测湍流动能最小、最大分布方向上分别对应的最小最大湍流动能的风速谱进行了研究,进一步检验了局地相似理论在城市冠层上下的适用性。结果表明:(1)城市冠层之上水泥、砖石等构成下垫面和城市冠层之内草坪下垫面观测感热通量、摩擦速度较为接近,观测潜热通量、CO2通量在白天差异明显。(2)城市冠层之上的湍流动能总体上大于冠层之内,冠层之上气流来向的上风向较为开阔时湍流动能较大,而冠层之内气流来向的上风向为街道口时湍流动能较大。(3)城市冠层之上的湍涡尺度大于冠层之内,城市冠层小尺度湍涡风速谱在惯性副区基本符合-2/3次方关系,且准各向同性,大尺度湍涡风速谱在惯性副区不符合-2/3次方关系,且各向异性。(4)不稳定层结下,城市冠层上下无量纲速度方差与稳定度基本满足1/3次方局地相似关系,稳定层结下不满足;城市冠层上下无量纲温度、湿度、CO2浓度方差在所有层结下均不满足-1/3次方局地相似关系。(5)近中性层结下,城市冠层上下u、v、w方向无量纲速度方差分别为3.52,3.03,1.49和2.62,2.22,1.50。 相似文献
11.
We present the power spectra of wind velocity and the cospectra of momentum and heat fluxes observed for different wind directions
over flat terrain and a large valley on the Loess Plateau. The power spectra of longitudinal (u) and lateral (v) wind speeds satisfy the −5/3 power law in the inertial subrange, but do not vary as observed in previous studies within
the low frequency range. The u spectrum measured at 32 m height for flow from the valley shows a power deficit at intermediate frequencies, while the v spectrum at 32 m downwind of the valley reaches another peak in the low frequency range at the same frequency as the u spectrum. The corresponding peak wavelength is consistent with the observed length scale of the convective outer layer at
the site. The v spectrum for flat terrain shows a spectral gap at mid frequencies while obeying inner layer scaling in its inertial subrange,
suggesting two sources of turbulence in the surface layer. All the spectra and cospectra from the valley direction show a
height dependency over the three levels. 相似文献
12.
Meteorological data of velocity components and temperature have been measured on a mast of height 4.9 m at one site in the Heihe River Basin Field Experiment (HEIFE) conducted in west China. Mean and individual turbulence parameters, power spectra/cospectra, phase angles and their changes withfetch downwind of a change in surface roughness were analyzed. The turbulence characteristics depend strongly on the prevailing wind direction, which in turn is associated with changes in the upwind surface roughness pattern. The results show that values of horizontal velocity standard deviations sigma;u,v scaled with local friction velocity u under different stratifications are larger than those over flat terrain, while the values of w/u have the same values as over flat terrain. The differences between variance values of the horizontal velocity components, u and v, over inhomogeneous terrain were found to be significantly smaller than those over flat terrain. Since energy densities of the w spectra, uw and wT cospectra at low frequencies are relatively lower than those of longitudinal velocity spectra, total energies of w spectra, uw and wT cospectra tend to be in equilibrium with the local terrain. The values of phase angles at the low frequency end of the frequency showed obvious differences associated with changes of roughness. 相似文献
13.
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. 相似文献
14.
SPECTRAL CHARACTERISTICS OF SURFACE-LAYER TURBULENCE OVER THE SUBURBS OF TIANJIN 总被引：1，自引：0，他引：1 
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下载免费PDF全文 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. 相似文献
15.
天津市郊大气边界层湍谱特征分析 总被引：10，自引：2，他引：10
用１９９０年７月在天津市郊的观测资料，计算了风速谱、温度谱及动量和热量通量的协谱。结果表明，市郊下垫面上的大气湍流谱特征与平坦地形上得到的典型结果基本一致，但满足各向同性的湍流尺度似乎比在平坦地形上的略大，谱的峰值频率区域略窄，谱的低频区（含能区）特征与平坦地形上的情况也不同。 相似文献
16.
Atmospheric turbulence is an important factor in the modelling of wind forces on structures and the losses they produce in
extreme wind events. However, while turbulence in non-hurricane winds has been thoroughly researched, turbulence in tropical
cyclones and hurricanes that affect the Gulf and Atlantic coasts has only recently been the object of systematic study. In
this paper, Florida Coastal Monitoring Program surface wind measurements over the sea surface and open flat terrain are used
to estimate tropical cyclone and hurricane wind spectra and cospectra as well as integral length scales. From the analyses
of wind speeds obtained from five towers in four hurricanes it can be concluded with high confidence that the turbulent energy
at lower frequencies is considerably higher in hurricane than in non-hurricane winds. Estimates of turbulence spectra, cospectra,
and integral turbulence scales presented can be used for the development in experimental facilities of hurricane wind flows
and the forces they induce on structures. 相似文献
17.
Turbulence Characteristics of the Stable Boundary Layer Over a Mid-Latitude Glacier. Part I: A Combination of Katabatic and Large-Scale Forcing 总被引：1，自引：1，他引：0
Profile and eddy-correlation (heights of 4 and 10 m) measurements performed on the Pasterze glacier (Austria) are used to study the characteristics of the stable boundary layer under conditions of katabatic and large-scale forcing. We consider cases where large-scale forcing results in a downslope (or following) ambient wind. The analysis of averaged spectra and cospectra reveals low frequency perturbations that have a large influence on the variances of temperature and horizontal wind components and also alter the cospectra of momentum and sensible heat flux. Only the spectrum of the vertical wind speed is comparable to universal spectra. The low frequency perturbations occur as brief intermittent events and result in downward entrainment of ambient air thereby producing enhanced downward sensible heat fluxes and downward as well as upward momentum fluxes with various magnitudes and timescales. After the variances were high pass filtered, the normalised standard deviations of wind speed and temperature compare favourably to findings in the literature within the range 0>z/L>0.5. For larger z/L they deviate as a result of an increased influence from low frequency perturbations and thus non-stationarity. In line with this, the turbulent kinetic energy budget (at 4 m height) indicates that production (shear) is in balance with destruction (buoyancy and dissipation) within the range 0>z/L>0.3. Non-dimensional gradients of wind speed within the range 0>z/L>0.3 have a slope of about 3.5. The scatter for the dimensionless temperature gradient is quite large, and the slope is comparable to that for wind speed gradients. For z/L>0.3 the imbalance in the turbulent kinetic energy budget grows and non-dimensional gradients for wind speed and temperature deviate considerably from accepted values as a result of increased non-stationarity. Average roughness lengths for momentum and sensible heat flux derived from wind speed and temperature profiles are respectively 1 × 10-3 m and 6 × 10-5 m, consistent with the literature. The ratio (z0h/z0m) compares to those predicted by surface renewal models. A variation of this ratio with the roughness Reynolds number is not indicated by our data. 相似文献
18.
北京城郊近地层湍流实验观测 总被引：13，自引：2，他引：13
本文利用两台FA-11超声风速温度仪于1992年3月到４月间在北京325 m气象观测塔47 m和120 m两个高度观测到的风速三个正交分量以及声虚温的湍流脉动资料，计算和分析了北京城郊粗糙下垫面近地层湍流特征量及其日变化，无量纲垂直速度和声虚温的方差随稳定度的变化，风速分量和温度的归一化湍流能谱以及动量和热通量的互谱及其随稳定度的变化。并且与平坦均一下垫面近地层湍流观测的结果进行了对比。 相似文献
19.
城市边界层动量和保守物通量的特征 总被引：2，自引：0，他引：2
利用2005年1-5月北京325 m气象塔47 m高度的湍流脉动资料(风速、温度、水汽和CO2),对城市边界层冠层内的湍流运动统计特征(相似关系、高阶矩、通量和谱等)进行了分析。其中,谱分析的结果表明,城市冠层内稳定度对湍流谱的影响比较小,而水平风速的影响比较大。因此,速度和温度的相似关系在夜间稳定条件下也成立。但是,由于水汽和CO2还受其他因素的影响,相似关系并不适用。更高阶矩的研究表明它们的陡峭度与偏斜度之间存在平方关系。而水汽和CO2之间也存在差异,它们的通量日变化特征明显不同,CO2通量的日变化更能体现人类活动的影响。同时,感热通量、潜热通量和CO2通量存在季节变化,尤其是潜热通量季节差异很大。 相似文献
20.
Boundary-layer flow over very rough surfaces is poorly understood so the applicability of standard micrometeorological theory is uncertain. This study presents observations of the turbulent fluctuations of meteorological parameters over a suburban area. Even though the height of measurement is considered to be close to the junction between the inertial and roughness sub-layers, the wind and temperature spectra and the momentum and sensible heat flux cospectra are in good agreement with reference data from smoother surfaces. Recommendations are made concerning site requirements, height of measurement and averaging times for the study of turbulence and turbulent fluxes over suburban terrain. 相似文献