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1.
从湍流经典理论到大气湍流非平衡态热力学理论 总被引：2，自引：0，他引：2
湍流是日常生活中一种普遍的自然现象,也是经典物理学仍未完全解决的难题。湍流更是大气运动的最基本特征。本文系统地回顾了大气湍流经典理论发展简史,进一步详细介绍了大气湍流非平衡态热力学理论。大气湍流非平衡态热力学理论在熵平衡方程中引入动力过程,进而统一推导出大气湍流输送的Fourier定律、Flick定律和Newton定律,证明了Dufour效应、Soret效应、可逆动力过程与热力不可逆湍流输送过程之间的交叉耦合效应,以及湍流强度定理。这些定律和定理中得到了观测的事实验证,同时它们的唯象系数也由观测资料所确定。湍流强度定理揭示,湍流发展的宏观原因是速度和温度的剪切效应,Reynolds湍流和Rayleigh-Bénard湍流共存于大气湍流中。热力过程和动力过程间耦合效应现象的发现突破了传统湍流输送理论,即Fourier定律、Flick定律和Newton定律的观点——一个宏观量的输送通量等价于这个宏观量的梯度湍流输送通量。热力和动力过程间的耦合原理认为,一个宏观量的输送通量包括这个量的梯度湍流输送通量和速度耦合输送通量两部分。因此,能量和物质的垂直输送通量除了相应物理量梯度造成的湍流输送外,还应包括垂直速度耦合效应,即辐散或辐合运动造成的耦合效应。在一个很宽的尺度范围内,地表面的空间特征是非均匀的。下垫面非均匀性造成的对流运动将引起大气的辐散或辐合运动。这可能是导致地表能量收支不平衡的重要原因之一。垂直速度对垂直湍流输送的交叉耦合效应为非均匀下垫面大气边界层理论的发展,并为克服地表能量收支不平衡问题及非均匀下垫面大气边界层参数化遇到的困难提供了可能的线索。 相似文献
2.
It has been proved that there exists a cross coupling
between vertical heat turbulent transport and vertical velocity by
using linear thermodynamics. This result asserts that the vertical
component of heat turbulent transport flux is composed of both the
transport of the vertical potential temperature gradient and the
coupling transport of the vertical velocity. In this paper, the
coupling effect of vertical velocity on vertical heat turbulent
transportation is validated by using observed data from the
atmospheric boundary layer to determine cross coupling coefficients,
and a series of significant properties of turbulent transportation
are opened out. These properties indicate that the cross coupling
coefficient is a logarithm function of the dimensionless vertical
velocity and dimensionless height, and is not only related to the
friction velocity u*, but also to the coupling roughness
height zW0 and the coupling temperature TW0 of the
vertical velocity. In addition, the function relations suggest that
only when the vertical velocity magnitude conforms to the limitation
|W/u*|≠1, and is above the level zW0, then the
vertical velocity leads to the cross coupling effect on the vertical
heat turbulent transport flux. The cross coupling theory and
experimental results provide a challenge to the traditional
turbulent K closure theory and the Monin-Obukhov similarity
theory. 相似文献
3.
陆气相互作用对中尺度对流系统影响的研究进展 总被引：1，自引：1，他引：0
文章回顾了大气对地表性质的敏感性研究,以及陆气相互作用对中尺度天气过程的影响,说明了地表性质与积云对流及对流降水之间的联系。地表性质的改变对行星边界层的热通量、水汽通量、对流有效位能产生影响,并通过湍流的垂直输送,进而影响到其上大气的性质。陆气之间存在着复杂的、非线性的相互作用。性质不均匀的下垫面造成地表向大气感热通量和潜热通量的差异,从而在近地层大气中形成温度和气压梯度,产生局地环流,在条件适合的情况下可以形成对流,并产生降水,而降水的不均匀分布,又维持了下垫面的不均匀性。土壤湿度对对流的影响受到多个因素的制约,其中天气尺度过程的影响是很显著的;由非均匀的下垫面所产生的局地环流能够触发积云对流。 相似文献
4.
采用北京大学三维的复杂地形中尺度模式,结合陆面过程模式(SiB),模拟了草原和沙漠并存的下垫面的边界层大气运动.利用SiB模式计算了地表辐射、感热、潜热通量,并且预报地表温度.中尺度模式则模拟了沙漠地区受热抬升,形成的辐合运动,垂直速度的分布,不同高度上水平流场的变化以及中尺度动量和热量通量,把中尺度通量跟湍流通量进行了比较,以确定这种中尺度运动在GCM模式的参数化过程中的重要性.试验表明中尺度通量尤其是热量通量要比湍流通量大很多. 相似文献
5.
凝结潜热释放和地表热通量对一次飑线过程的影响 总被引：2，自引：0，他引：2
针对2013年7月4—5日一次产生大风、短时强降水强对流天气的飑线过程进行数值试验,研究了凝结潜热释放和地表热通量在中尺度对流系统的发生发展过程中的影响。结果表明:(1)凝结潜热释放对飑线系统有重要的作用,对飑线发展维持、移动及成熟阶段的垂直结构都有着一定影响。(2)当飑线系统进入成熟阶段后,小尺度的积云对流中的凝结加热作用于中高层大气,加强了高层辐散低层辐合的配置,而对流系统内垂直上升运动的加强又导致凝结加热作用更强。(3)凝结加热作用极大地促进了飑线的低层入流、高层出流的垂直结构,以及系统前方中层入流和高层出流之间形成的间接垂直反环流,促进高空动能下传的同时,使系统前方对流不稳定性增加,新的对流单体易于触发。(4)潜热释放间接增强了对流内部的冷性下沉气流,进而加强了低层的阵风锋,使得新的对流单体能在飑锋处触发,飑线以新老对流单体交替的方式向前移动。(5)在高低空急流的垂直耦合促进飑线发展的同时,成熟阶段飑线中较强的凝结加热对高低层急流有反馈作用,一定程度上增强了这种垂直耦合。(6)地表感热、潜热通量等边界层非绝热过程在对流系统的触发和发展中起到了较为重要的作用。地表热通量在白天加强了对流边界层的湍流混合作用,由此产生的特征维持到了夜间,形成了适合飑线触发的层结条件。另外,在对流形成之前,与地表潜热通量相关的边界层加湿作用为对流的爆发贮存了丰富的水汽和不稳定能量。 相似文献
6.
Keith Julien Sonya Legg Jim McWilliams Joseph Werne 《Dynamics of Atmospheres and Oceans》1996,24(1-4)
Turbulent convection forced by a surface heat flux into a stably stratified region is a feature of both the atmospheric and oceanic planetary boundary layers. Of particular interest is the interface between the convective layer and the stable stratification, where the entrainment of fluid into the convective layer by penetrating plumes may lead to a reverse buoyancy flux, and an enhancement of the stable stratification. Whereas in the atmosphere the influence of rotation on this penetrative convection is negligible, oceanic convection may be subjected to lower Rossby numbers and hence greater rotational influence. To isolate the effects of rotation, we present three numerical solutions for turbulent penetrative convection, characterised by different rotation rates, with all other parameters being held constant. Our results indicate that at lower Rossby numbers the lateral scale of the plumes is reduced, whereas the vertical vorticity of the plumes is much enhanced. Vertical transports of buoyancy and kinetic energy across the convective layer are reduced, leading to less efficient penetration at the interface with the stratified layer, and hence less reverse buoyancy flux in this region. 相似文献
7.
建立了一个农林复合带地区一维非静力大气边界层能量闭合模式，对1000m以下的大气边界层内的风、温、湿作了24h的预报，并对下垫面3种不同参数化方案(农作物、森林、无植被)的输出结果与实测值进行了分析和比较；同时通过敏感性试验，突出比较了农作物和森林下垫面对大气边界层垂直流场，湍流垂直交换和湍能的影响。结果表明，本模式能改善边界层风速、位温和湿度预报的模拟效果，下垫面植被对边界层气象要素大小和分布有显著的作用，对湍能垂直分布有一定影响。 相似文献
8.
An observational analysis of the structures and characteristics of a windy atmospheric boundary layer during a cold air outbreak in the South China Sea region is reported in this paper. It is found that the main structures and characteristics are the same as during strong wind episodes with cold air outbreaks on land. The high frequency turbulent fluctuations(period<1 min) are nearly random and isotropic with weak coherency, but the gusty wind disturbances(1 min相似文献
9.
10.
Helmut Kraus 《Boundary-Layer Meteorology》1971,1(4):385-388
The paper deals with the role of the vertical flux of turbulent energy in the atmospheric boundary layer. The influence of the divergence of this flux on the vertical wind profile and on the eddy diffusivity is shown by theoretical considerations. 相似文献
11.
该文在多尺度湍流理论的研究成果基础上, 将边界层湍流风谱与平均量的梯度相联系, 建立了边界层多尺度湍流参数化子模式, 之后放入MM5模式中进行了个例模拟研究, 并与MM5模式附带的M RF边界层参数化、Blackadar高分辨率边界层参数化的模拟结果进行比较和分析。结果表明, 多尺度湍流理论能够反映出实际大气边界层中热量垂直输送的规律, 将其用于中尺度数值预报模式的边界层物理过程参数化是可行的; 多尺度湍流参数化在地表层和边界层内各个层次上都着重考虑含能量最大的涡的作用以及水平热力不均匀性的影响, 因此在地形和下垫面比较复杂的区域, 对中尺度天气系统的模拟有进一步发展的前景。 相似文献
12.
西北干旱区夏季大气边界层结构及其陆面过程特征 总被引：18，自引：3，他引：15
在中国西北干旱区影响大气边界层形成和发展的气候环境和大气环流背景都具有一定特殊性.文中用外场观测试验资料,分析了位于西北干旱区的敦煌荒漠夏季大气边界层气象要素结构特征,发现该地区无论白天的对流边界层还是夜间的稳定边界层均比一般地区更深厚.在夏季晴天,夜间稳定边界层厚度超过900 m,最厚可以达到1750 m,其上的残余层一般能达到4000 m左右的高度;白天混合层最高达3700 m,混合层顶的逆温层顶盖的厚度大约450 m,甚至更厚,对流边界层厚度能够超过4000 m,对流边界层进入残余层后发展十分迅速.研究表明,白天深厚的对流边界层是夜间保持清晰而深厚的残余混合层的先决条件,夜间深厚的残余混合层又为白天对流边界层的发展提供了一个非常有利的热力环境条件.该地区经常性出现连续性晴天使得大气残余层的累积效应得以较长时间持续发展,创造了比较有利于大气对流边界层发展的大气热力环境条件.同时,该地区陆面过程和近地层大气运动特征也为这种独特的大气热力边界层结构提供了较好的支持.就该地区发展超厚大气对流边界层的物理机理而言,地表显著增温是强有力的外部热力强迫条件,近地层强感热通量提供了较充足的能量条件,较大的对流运动和湍流运动的速度是必要的运动学条件,大气残余层的累积效应提供了有利的热力环境条件. 相似文献
13.
Stefan Zacharias Mark Reyers Joaquim G. Pinto Jan H. Schween Susanne Crewell Michael Kerschgens 《Meteorology and Atmospheric Physics》2012,117(1-2):47-61
High-resolution simulations with a mesoscale model are performed to estimate heat and moisture budgets of a well-mixed boundary layer. The model budgets are validated against energy budgets obtained from airborne measurements over heterogeneous terrain in Western Germany. Time rate of change, vertical divergence, and horizontal advection for an atmospheric column of air are estimated. Results show that the time trend of specific humidity exhibits some deficiencies, while the potential temperature trend is matched accurately. Furthermore, the simulated turbulent surface fluxes of sensible and latent heat are comparable to the measured fluxes, leading to similar values of the vertical divergence. The analysis of different horizontal model resolutions exhibits improved surface fluxes with increased resolution, a fact attributed to a reduced aggregation effect. Scale-interaction effects could be identified: while time trends and advection are strongly influenced by mesoscale forcing, the turbulent surface fluxes are mainly controlled by microscale processes. 相似文献
14.
H. L. Kuo 《Boundary-Layer Meteorology》1979,17(1):29-39
Previous theoretical and observational investigations have shown that vertical plumes are formed in the high Rayleigh number convection field over heated horizontal surfaces and that these plumes become unsteady and turbulent when the Rayleigh number is higher than about 20 times its critical value R
c. Based on these results, we conclude that the dissipation of kinetic energy takes place mainly in the surface boundary layer in high Rayleigh number laminar convection and mainly in the vertical plumes in turbulent convection, while the conversion of eddy potential energy into kinetic energy is accomplished mainly in the well-mixed main body of the fluid. On making use of these rather general conclusions concerning the kinetic energy generation and dissipation processes in the energy integrals, we are able to derive the well known 5/4 and 4/3 power laws of upward heat transfer by laminar and turbulent convections theoretically. 相似文献
15.
SENSITIVITY TESTS OF INTERACTION BETWEEN LAND SURFACE PHYSICAL PROCESS AND ATMOSPHERIC BOUNDARY LAYER* 
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下载免费PDF全文 LIU Shuhu WEN Pinghui ZHANG Yunyan HONG Zhongxiang HU Fei LIU Huizhi 《Acta Meteorologica Sinica》2002,16(4):451-469
In this paper,an interactive model between land surface physical process and atmosphere boundary layer is established,and is used to simulate the features of soil environmental physics,surface heat fluxes,evaporation from soil and evapotranspiration from vegetation and structures of atmosphere boundary layer over grassland underlying.The sensitivity experiments are engaged in primary physics parameters.The results show that this model can obtain reasonable simulation for diurnal variations of heat balance,soil volumetric water content,resistance of vegetation evaporation,flux of surface moisture,and profiles of turbulent exchange coefficient,turbulent momentum,potential temperature,and specific humidity.The model developed can be used to study the interaction between land surface processes and atmospheric boundary layer in city regions,and can also be used in the simulation of regional climate incorporating a mesoscale model. 相似文献
16.
SENSITIVITY TESTS OF INTERACTION BETWEEN LAND SURFACE PHYSICAL PROCESS AND ATMOSPHERIC BOUNDARY LAYER 总被引：3，自引：0，他引：3
In this paper,an interactive model between land surface physical process and atmosphereboundary layer is established,and is used to simulate the features of soil environmental physics,surface heat fluxes,evaporation from soil and evapotranspiration from vegetation and structures ofatmosphere boundary layer over grassland underlying.The sensitivity experiments are engaged inprimary physics parameters.The results show that this model can obtain reasonable simulation fordiurnal variations of heat balance,soil volumetric water content,resistance of vegetationevaporation,flux of surface moisture,and profiles of turbulent exchange coefficient,turbulentmomentum,potential temperature,and specific humidity.The model developed can be used tostudy the interaction between land surface processes and atmospheric boundary layer in cityregions,and can also be used in the simulation of regional climate incorporating a mesoscalemodel. 相似文献
17.
Yeong-Jer Lin 《Boundary-Layer Meteorology》1988,44(4):349-357
Dual-Doppler data collected from 1646 to 1648 MDT on 14 July, 1982 in Colorado were employed to study the eddy kinetic energy budget in the subcloud layer of a microburst-producing thunderstorm during its mature stage. Each term in the budget equation was computed from the Doppler-derived winds and retrieved thermodynamic fields within the 10 by 10 km horizontal domain. Results show that in the atmospheric boundary layer (ABL) where the microburst dominates, the turbulent flow extracts energy from the mean flow in order for the microburst to maintain its strong diverging outflow at low levels. The vertical transport of eddy kinetic energy is predominantly downward in the low layer due to the organized downdrafts in the microburst area. The horizontal flux convergence (divergence) of eddy kinetic energy by the mean and eddying motions is approximately balanced by that of the vertical flux divergence (convergence). Similarly, the contributions from the pressure and buoyancy production terms are nearly in balance. As a result, a net change of the eddy kinetic energy generation in the subcloud layer is relatively small in comparison with the individual term in the budget equation. 相似文献
18.
非均匀网格的过渡湍流理论及其在大气边界层数值模拟中的应用 总被引：1，自引：1，他引：1
本文将Stull提出的均匀网格下的过渡湍流理论推广到非均匀网格情形，推广的非均匀网格的过渡湍流理论满足Stull提出的对过渡矩阵系数的要求并具有清晰的物理意义。然后，将非均匀网格的过渡湍流理论应用于一维大气边界层数值模式中，对Wangara资料进行了模拟，并与均匀网格情形进行了对比。计算表明，非均匀网格的过渡湍流模式能很好地模拟Wangara大气边界层平均量与湍流量的变化；本文非均匀网格的过渡湍流理论的推广是可行的，它可能会在大气边界层数值模拟及其他方面（如：中尺度模式）得到应用。 相似文献
19.
Numerical Simulation Experiment of Land Surface Physical Processes and Local Climate Effect in Forest Underlying Surface 总被引：1，自引：0，他引：1 下载免费PDF全文
下载免费PDF全文 LIU Shuhu PAN Ying DENG Yi MA Mingmin JIANG Haimei LIN Hongtao JIANG Haoyu LIANG Fuming LIU Heping WANG Jianhua 《Acta Meteorologica Sinica》2006,20(1):72-85
Based on the basic principles of atmospheric boundary layer and plant canopy micrometeorology, a forest underlying surface land surface physical process model and a two-dimensional atmospheric boundary layer numerical model are developed and numerical simulation experiments of biosphere and physiological processes of vegetation and soil volumetric water content have been done on land surface processes with local climate effect. The numerical simulation results are in good agreement with realistic observations, which can be used to obtain reasonable simulations for diurnal variations of canopy temperature, air temperature in canopy, ground surface temperature, and temporal and spatial distributions of potential temperature and vertical wind velocity as well as relative humidity and turbulence exchange coefficient over non-homogeneous underlying surfaces. It indicates that the model developed can be used to study the interaction between land surface process and atmospheric boundary layer over various underlying surfaces and can be extended to local climate studies. This work will settle a solid foundation for coupling climate models with the biosphere. 相似文献
20.
Summary An aircraft-based experimental investigation of the atmospheric boundary layer (ABL) structure and of the energy exchange
processes over heterogeneous land surfaces is presented. The measurements are used for the validation of the mesoscale atmospheric
model “Lokal-Modell” (LM) of the German Weather Service with 2.8 km resolution. In addition, high-resolution simulations using
the non-hydrostatic model FOOT3DK with 250 m resolution are performed in order to resolve detailed surface heterogeneities.
Two special observation periods in May 1999 show comparable convective boundary layer (CBL) conditions. For one case study
vertical profiles and area averages of meteorological quantities and energy fluxes are investigated in detail. The measured
net radiation is highly dependent on surface albedo, and the latent heat flux exhibits a strong temporal variability in the
investigation area. A reduction of this variability is possible by aggregation of multiple flight patterns. To calculate surface
fluxes from aircraft measurements at low altitude, turbulent energy fluxes were extrapolated to the ground by the budget method,
which turned out to be well applicable for the sensible heat flux, but not for the latent flux. The development of the ABL
is well captured by the LM simulation. The comparison of spatiotemporal averages shows an underestimation of the observed
net radiation, which is mainly caused by thin low-level clouds in the LM compared to observed scattered CBL clouds. The sensible
heat flux is reproduced very well, while the latent flux is highly overestimated especially above forests. The realistic representation
of surface heterogeneities in the investigation area in the FOOT3DK simulations leads to improvements for the energy fluxes,
but an overestimation of the latent heat flux still persists. A study of upscaling effects yields more structures than the
LM fields when averaged to the same scale, which are partly caused by the non-linear effects of parameter aggregation on the
LM scale. 相似文献