Probabilistic comparison between turbulence closure model and Bulk Richardson Number approach for ABL height estimation using copula     

《Dynamics of Atmospheres and Oceans》2019

In this paper, a numerical study has been carried out to assess changes in Atmospheric Boundary Layer (ABL) height under changing hydro-climatic conditions. ABL height is estimated by using the data from experiments conducted at three different sites- LAnd Surface Process EXperiment (LASPEX-97) in Sabarmati river basin, Gujarat, India, during 1997; Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) in Lannemezan, France, during 2011 and Integrated Global Radiosonde Archive (IGRA) in Tucson at Arizona, USA, during 2011. Here ABL height is estimated, during Intensive Observation Period (IOP), using 1-D turbulence closure model at all three site locations as well as following the Bulk Richardson Number (BRN) Approach. For LASPEX-97 only, the 1-D model with module for sub-surface processes coupled with upper-surface model is used for the estimation and compared with the only upper-surface model. ABL height, estimated by the coupled model, is found to be slightly higher than that by the un-coupled model. A copula-based analysis indicates that ABL height estimated by the 1-D model and same by BRN-based approach are statistically similar within 90% confidence interval (CI) under similar stratification condition. Thus, it validates the 1-D turbulence closure model for ABL height estimation. The sensitivity analysis of height of ABL, derived by 1-D model, against critical parameters reveals that surface condition (soil temperature) is more critical than atmospheric condition (net radiation) in forcing change on height of ABL in summer.  相似文献   

阵风因子与大气边界层要素的关系及预报试验     

胡波 《气象科技》2019,47(2):282-288

利用2008—2016年舟山4个海岛气象站大风资料和欧洲中心的ERA-interim再分析资料,分析了阵风因子随平均风速、风向、小时、月份等分布的气候特征,统计阵风因子与边界层的大气稳定度、250～1000m风速与10m风速的比值、6h变温等要素的相关后,选取最佳预报因子,利用BP人工神经网络方法,根据不同因子组合对阵风进行循环试报。结果表明:①平均风速较小时阵风因子波动范围大;靠近大陆站点的阵风因子及来自陆地方向气流的阵风因子偏大。②白天11:00—16:00受太阳辐射影响大气湍流相对较强,阵风因子偏大。7—9月沿海受台风影响频繁,其阵风因子要大些,而11—12月阵风因子偏大则与来流方向的地表粗糙度较大有关。③阵风因子和边界层不同高度的风速与10m风速比值,及气温具有明显正相关,与边界层大气稳定度参数具有负相关,相关结果印证了阵风主要物理成因与动量的垂直湍流输送有关。④阵风循环试报表明最佳组模型试报的绝对误差及方差均比对比组模型减少约11%～25%,具有较好的预报效果。  相似文献   

人为热源和城市绿化对冬季山谷城市边界层结构影响的数值模拟   总被引：3，自引：3，他引：0       下载免费PDF全文

杨胜朋  吕世华  陈玉春  奥银焕  余晔  王长友 《高原气象》2009,28(2):268-277

为了探讨人为热源和城市绿化对城市边界层的影响,本文在RAMS模式中引入周期性日变化的人为热源和人工改变下垫面状况,初步模拟分析了人为热源和城市绿化对城市边界层结构的影响.结果表明:人为热源具有明显的增温效应,增强了城市的湍流交换,白天增加了大气不稳定度,促进了混合层的发展,夜间降低了大气稳定度,减弱了城市夜间逆温.城市绿化减小了地表反照率,增加了到达地面的净辐射,模拟期间土壤冻结,增加的净辐射其中一部分以感热的形式来加热大气;绿化后地气之间的湍流交换增强,增加了大气不稳定度,减弱了白天高空逆温;本文还讨论了不同绿化布局对白天高空逆温的影响以及人为热源和城市绿化之间的非线性相互作用.  相似文献   

旋转扰动流体中壁面湍流不稳定及其拟序结构研究I：实验     

Arnaldo  Longhetto  Enrico  Ferrero  张瑛  全利红  Massimiliano  Manfrin  Luca  Mortarini  Renato  Forza 《气象与减灾研究》2009,32(3):15-18

重点介绍和讨论了中性条件下旋转扰动流体中边界层强迫不稳定及其相关的一些问题,阐述了旋转体系中切变驱动边界层不稳定的动力学特征。这些不稳定状态的研究在大气物理学、流体动力学、海洋学等多个领域中引起科学家极大的兴趣,近年来在实验和理论研究中都得到了不断的发展。意大利都灵大学基础物理系地球科学实验组通过水槽旋转实验方法,不断改变水槽启动或结束时的旋转运动速度,以及底部壁面粗糙度等要素,所得到的实验结果与SDBL理论非常一致。  相似文献   

旋转扰动流体中壁面湍流不稳定及其拟序结构研究Ⅰ:实验     

Enrico Ferrero  张瑛  全利红  Luca Mortarini  Renato Forza 《气象与减灾研究》2009,32(3)

重点介绍和讨论了中性条件下旋转扰动流体中边界层强迫不稳定及其相关的一些问题,阐述了旋转体系中切变驱动边界层不稳定的动力学特征.这些不稳定状态的研究在大气物理学、流体动力学、海洋学等多个领域中引起科学家极大的兴趣,近年来在实验和理论研究中都得到了不断的发展.意大利都灵大学基础物理系地球科学实验组通过水槽旋转实验方法,不断改变水槽启动或结束时的旋转运动速度,以及底部壁面粗糙度等要素,所得到的实验结果与SDBL理论非常一致.  相似文献   

Auto　CAD技术在市政工程系列图成图上的应用     

万刚 《测绘学院学报》1995,(2)

本文通过对ＡｕｔｏＣＡＤ技术的二次开发，实现了市政工程系列图图形的直观显示、编码管理、快速成图等功能。  相似文献   

Study on the Thermal internal Boundary Layer and Dispersion of Air Pollutant     

Jiang Weimei  Yu Hongbin 《大气科学进展》1994,11(3):285-290

ＳｔｕｄｙｏｎｔｈｅＴｈｅｒｍａｌｉｎｔｅｒｎａｌＢｏｕｎｄａｒｙＬａｙｅｒａｎｄＤｉｓｐｅｒｓｉｏｎｏｆＡｉｒＰｏｌｌｕｔａｎｔｉｎＣｏａｓｔａｌＡｒｅａｂｙＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎ￥ＪｉａｎｇＷｅｉｍｅｉ（蒋维楣）ａｎｄＹｕＨｏｎｇ...  相似文献   

Thermal decomposition of NH<Subscript>4</Subscript><Superscript>+</Superscript>-vermiculite from Santa Olalla (Huelva,Spain) and its relation to the metal ion distribution in the octahedral sheet     

J. L.?Pérez-RodríguezEmail author  J.?Poyato  M. C.?Jiménez de Haro  L. A.?Pérez-Maqueda  A.?Lerf 《Physics and Chemistry of Minerals》2004,31(7):415-420

The investigation of the NH₃ loss in the NH₄⁺-vermiculite (Santa Olalla) by thermogravimetry, evolved gas analysis, chemical analysis, X-ray diffraction and IR spectroscopy is reported here. The mass loss during heating takes place in two steps at about 650 and 825 °C. Additionally, the releases of H₂O and NH₃ occurs simultaneously. The experimental results indicate that the protons remaining in the interlayer space after NH₃ removal trigger the H₂O release. X-ray diffraction shows that during the decomposition of NH₄⁺-vermiculite there are two domains with different interlayer spaces at ~9 and ~10 Å. As the decomposition proceeds, the intensity of the 9 Å peak increases at the expense of the second one. The change in the IR-stretching modes of the structural OH groups during heating indicates that the OH groups surrounded by 3Mg²⁺ or 2Mg²⁺Fe²⁺ are released at lower temperatures than those with environments like 2Mg²⁺Fe³⁺, 2Mg²⁺Al³⁺ or more complex ones.  相似文献   

Numerical study of the effects of urban heat island on the characteristic features of the sea breeze circulation     

Abhijit Sarkar  R. S. Saraswat  A. Chandrasekar 《Journal of Earth System Science》1998,107(2):127-137

A two-dimensional numerical model is employed to study the effect of the coastal urban heat island on the sea breeze front and the thermal internal boundary layer height. The temperature at the land surface is determined by solving an energy budget equation. The effect of the urban heat island is studied by varying the width of the region and its intensity. During the early afternoon, the presence of the urban heat island enhances the strength of convergence of the sea breeze front and also reduces its inland penetration. The presence of the urban heat island causes increased thermal internal boundary layer height. Larger urban width causes larger vertical velocity and higher thermal internal boundary layer. Stronger convergence and higher thermal internal boundary layer are also obtained in case of larger heat island intensity.  相似文献   

A multi-limit formulation for the equilibrium depth of a stably stratified boundary layer   总被引：1，自引：0，他引：1  

Sergej Zilitinkevich  Dmitrii V. Mironov 《Boundary-Layer Meteorology》1996,81(3-4):325-351

Currently no expression for the equilibrium depth of the turbulent stably-stratified boundary layer is available that accounts for the combined effects of rotation, surface buoyancy flux and static stability in the free flow. Various expressions proposed to date are reviewed in the light of what is meant by the stable boundary layer. Two major definitions are thoroughly discussed. The first emphasises turbulence and specifies the boundary layer as a continuously and vigorously turbulent layer adjacent to the surface. The second specifies the boundary layer in terms of the mean velocity profile, e.g. by the proximity of the actual velocity to the geostrophic velocity. It is shown that the expressions based on the second definition are relevant to the Ekman layer and portray the depth of the turbulence in the intermediate regimes, when the effects of static stability and rotation essentially interfere. Limiting asymptotic regimes dominated by either stratification or rotation are examined using the energy considerations. As a result, a simple equation for the depth of the equilibrium stable boundary layer is developed. It is valid throughout the range of stability conditions and remains in force in the limits of a perfectly neutral layer subjected to rotation and a rotation-free boundary layer dominated by surface buoyancy flux or stable density stratification at its outer edge. Dimensionless coefficients are estimated using data from observations and large-eddy simulations. Well-known and widely used formulae proposed earlier by Zilitinkevich and by Pollard, Rhines and Thompson are shown to be characteristic of the above interference regimes, when the effects of rotation and static stability (due to either surface buoyancy flux, or stratification at the outer edge of the boundary layer) are roughly equally important.  相似文献