A Discussion on recent research in air pollution - The dispersion of pollutants in the free atmosphere by the large scale wind systems

1969 ◽  
Vol 265 (1161) ◽  
pp. 273-294 ◽  
Keyword(s):  
Wind Field ◽  
Large Scale ◽  
Three Dimensional ◽  
Horizontal Wind ◽  
Wind Fields ◽  
Free Atmosphere ◽  
Mean Values ◽  
Level Model ◽  
Small Factor ◽  
Numerical Forecast

The travel and dispersion of pollutants in the free atmosphere m ay be investigated by the direct measurement of the distributions of tracer materials such as water vapour, ozone and radioactive substances. Another method is to study the spread of pollutants from a constant point source or the expansion of large clusters, by using air trajectories found by tracking balloons or estimated from sequences of wind values obtained from synoptic charts. So far these latter techniques have usually only taken horizontal motions into account since the balloons are normally maintained at constant levels and the winds taken from the charts have been assumed to be geostrophic. In principle the effect of large (synoptic) scale vertical motions can be included by using the component wind fields given at the different time steps of a numerical forecast integration to construct suitable three-dimensional trajectories. A pilot study of this type at the 900, 700, 500 and 300 m bar pressure levels (90, 70, 50 and 30kN m ~2) using the results of a 24 h numerical forecast by the Meteorological Office’s 10 level model is described. In the case studied the use of constant level trajectories gave horizontal dispersions (variances of the trajectory end points relative to their centre of gravity) which differed by only small amounts from those due to the three dimensional trajectories. The zonal variances exceeded the meridional variances by a small factor and both were 4 to 6 orders greater than those of the corresponding variances in the vertical. In each case for at least 12 to 18 h they were all roughly proportional to the square of the time after release (the ‘short time’ case). The large scale clusters rapidly distorted at rates which increased with their initial size and also with the deformation components of the wind field. At these scales deformation plays a major role in the apparent dispersion and the mean values of total deformation so obtained agreed satisfactorily with those calculated from a kinematic analysis of the horizontal wind field.

scholarly journals Engineering Comprehensive Model of Complex Wind Fields for Flight Simulation

Aerospace ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 145
Author(s):  
Jianwei Chen ◽  
Liangming Wang ◽  
Jian Fu ◽  
Zhiwei Yang
Keyword(s):  
Wind Field ◽  
Three Dimensional ◽  
Great Influence ◽  
Spatial Location ◽  
Flight Simulation ◽  
Comprehensive Model ◽  
Flight Trajectory ◽  
Wind Fields ◽  
Wind Field Simulation ◽  
Low Level Jet

A complex wind field refers to the typical atmospheric disturbance phenomena existing in nature that have a great influence on the flight of aircrafts. Aimed at the issues involving large volume of data, complex computations and a single model in the current wind field simulation approaches for flight environments, based on the essential principles of fluid mechanics, in this paper, wind field models for two kinds of wind shear such as micro-downburst and low-level jet plus three-dimensional atmospheric turbulence are established. The validity of the models is verified by comparing the simulation results from existing wind field models and the measured data. Based on the principle of vector superposition, three wind field models are combined in the ground coordinate system, and a comprehensive model of complex wind fields is established with spatial location as the input and wind velocity as the output. The model is applied to the simulated flight of a rocket projectile, and the change in the rocket projectile’s flight attitude and flight trajectory under different wind fields is analyzed. The results indicate that the comprehensive model established herein can reasonably and efficiently reflect the influence of various complex wind field environments on the flight process of aircrafts, and that the model is simple, extensible, and convenient to use.

Impacts of Assimilating Measurements of Different State Variables with a Simulated Supercell Storm and Three-Dimensional Variational Method

2013 ◽  
Vol 141 (8) ◽  
pp. 2759-2777 ◽  
Author(s):  
Guoqing Ge ◽  
Jidong Gao ◽  
Ming Xue
Keyword(s):  
Potential Temperature ◽  
Three Dimensional ◽  
Horizontal Wind ◽  
Cold Pool ◽  
State Variables ◽  
Wind Fields ◽  
Simulation Experiments ◽  
Supercell Storm ◽  
The Impact ◽  
Analysis Quality

Abstract This paper investigates the impacts of assimilating measurements of different state variables, which can be potentially available from various observational platforms, on the cycled analysis and short-range forecast of supercell thunderstorms by performing a set of observing system simulation experiments (OSSEs) using a storm-scale three-dimensional variational data assimilation (3DVAR) method. The control experiments assimilate measurements every 5 min for 90 min. It is found that the assimilation of horizontal wind can reconstruct the storm structure rather accurately. The assimilation of vertical velocity , potential temperature , or water vapor can partially rebuild the thermodynamic and precipitation fields but poorly retrieves the wind fields. The assimilation of rainwater mixing ratio can build up the precipitation fields together with a reasonable cold pool but is unable to properly recover the wind fields. Overall, data have the greatest impact, while have the second largest impact. The impact of is the smallest. The impact of assimilation frequency is examined by comparing results using 1-, 5-, or 10-min assimilation intervals. When is assimilated every 5 or 10 min, the analysis quality can be further improved by the incorporation of additional types of observations. When are assimilated every minute, the benefit from additional types of observations is negligible, except for . It is also found that for , , and measurements, more frequent assimilation leads to more accurate analyses. For and , a 1-min assimilation interval does not produce a better analysis than a 5-min interval.

scholarly journals A Simulation Experiment to Retrieve the Atmospheric Density and Three-Dimensional Wind Field by Double Falling Spheres

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1312
Author(s):  
Yue Wu ◽  
Zheng Sheng ◽  
Xinjie Zuo ◽  
Minghao Yang
Keyword(s):  
Wind Field ◽  
Simulation Experiment ◽  
Middle Atmosphere ◽  
Three Dimensional ◽  
Optimal Solution ◽  
Vertical Wind ◽  
Horizontal Wind ◽  
Atmospheric Density ◽  
Falling Sphere ◽  
Falling Spheres

Falling-sphere sounding remains an important method for in situ determination in the middle atmosphere and is the only determination method within the altitude range of 60–100 km. Traditional single-falling-sphere sounding indicates only the atmospheric density and horizontal wind but not the vertical wind; the fundamental reason is that the equation set for retrieving atmospheric parameters is underdetermined. For tractability, previous studies assumed the vertical wind, which is much smaller than the horizontal wind, to be small or zero. Obtaining vertical wind profiles necessitates making the equations positive definite or overdetermined. An overdetermined equation set consisting of six equations, by which the optimal solution of density and three-dimensional wind can be obtained, can be established by the double-falling-sphere method. Hence, a simulation experiment is designed to retrieve the atmospheric density and three-dimensional wind field by double falling spheres. In the inversion results of the simulation experiment, the retrieved density is consistent with the constructed atmospheric density in magnitude; the density deviation rate does not generally exceed 20% (less than 5% below 60 km). The atmospheric density retrieved by the double-falling-sphere method is more accurate at low altitudes than the single-falling-sphere method. The vertical wind below 50 km and horizontal wind retrieved by double-falling-sphere method is highly consistent with the constructed average wind field. Additionally, the wind field deviation formula is deduced. These results establish the fact that the double-falling-sphere method is effective in detecting atmospheric density and three-dimensional wind.

scholarly journals Retrieving 3D Wind Field from Phased Array Radar Rapid Scans

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Xiaobin Qiu ◽  
Qin Xu ◽  
Chongjian Qiu ◽  
Kang Nai ◽  
Pengfei Zhang
Keyword(s):  
Wind Field ◽  
Adjoint Method ◽  
Phased Array ◽  
Elevation Angle ◽  
Three Dimensional ◽  
New Method ◽  
Horizontal Wind ◽  
Phased Array Radar ◽  
Temporal And Spatial ◽  
Vertical Winds

The previous two-dimensional simple adjoint method for retrieving horizontal wind field from a time sequence of single-Doppler scans of reflectivity and/or radial velocity is further developed into a new method to retrieve both horizontal and vertical winds at high temporal and spatial resolutions. This new method performs two steps. First, the horizontal wind field is retrieved on the conical surface at each tilt (elevation angle) of radar scan. Second, the vertical velocity field is retrieved in a vertical cross-section along the radar beam with the horizontal velocity given from the first step. The method is applied to phased array radar (PAR) rapid scans of the storm winds and reflectivity in a strong microburst event and is shown to be able to retrieve the three-dimensional wind field around a targeted downdraft within the storm that subsequently produced a damaging microburst. The method is computationally very efficient and can be used for real-time applications with PAR rapid scans.

The impact of large-scale winds on thermally driven flows and exchange processes over mountainous terrain

2020 ◽  
Author(s):  
Jan Weinkaemmerer ◽  
Ivan Bašták Ďurán ◽  
Jürg Schmidli
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Volume Effect ◽  
Turbulent Heat ◽  
Atmospheric Conditions ◽  
Free Atmosphere ◽  
Convective Boundary ◽  
Mean Values ◽  
Mountainous Regions ◽  
The Impact

<p>In the convective boundary layer over mountainous regions, the mean values and the fluxes of quantities like heat, mass, and momentum are strongly influenced by thermally induced flows. Several studies have pointed out that the enhanced warming of the air inside a valley can be explained by the valley-volume effect whereas the cross-valley circulation leads to a net export of heat to the free atmosphere. We are interested in the influence of an upper-level wind on the local circulations and the boundary-layer properties, both locally and in terms of the horizontal mean, as this aspect has not yet received much attention. LES are carried out over idealized, two-dimensional topographies using the CM1 numerical model. For the analysis, turbulent, mean-circulation, and large-scale contributions are systematically distinguished. Also, budget analyses are performed for the turbulence kinetic energy and the turbulent heat and mass flux. Based on the first results for periodic topographies, no crucial influence on the horizontally averaged heat-flux and temperature profile can be observed, even though the flow pattern of the thermal wind is qualitatively changed. In addition to that, the impact on moisture transport will be evaluated and simulations over different topographies as well as for different atmospheric conditions and surface properties will be presented.</p>

scholarly journals A Simulation Study of the Formation of Large-Scale Cyclonic and Anticyclonic Vortices in the Vicinity of the Intertropical Convergence Zone

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Igor V. Mingalev ◽  
Natalia M. Astafieva ◽  
Konstantin G. Orlov ◽  
Victor S. Mingalev ◽  
Oleg V. Mingalev ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Intertropical Convergence Zone ◽  
Lower Atmosphere ◽  
Horizontal Wind ◽  
Initial Moment ◽  
Convergence Zone ◽  
Height Range ◽  
Limited Region ◽  
Surface Time

A regional nonhydrostatic mathematical model of the wind system of the lower atmosphere, developed recently in the Polar Geophysical Institute, is utilized to investigate the initial stage of the origin of large-scale vortices at tropical latitudes. The model produces three-dimensional distributions of the atmospheric parameters in the height range from 0 to 15 km over a limited region of the Earth’s surface. Time-dependent modeling is performed for the cases when, at the initial moment, the simulation domain is intersected by the intertropical convergence zone (ITCZ). Calculations are made for various cases in which the initial forms of the intertropical convergence zone are different and contained convexities with distinct shapes, which are consistent with the results of satellite microwave monitoring of the Earth’s atmosphere. The results of modeling indicate that the origin of convexities in the form of the intertropical convergence zone, having distinct configurations, can lead to the formation of different large-scale vortices, in particular, a cyclonic vortex, a pair of cyclonic-anticyclonic vortices, and a pair of cyclonic vortices, during a period not longer than three days. The radii of these large-scale vortices are about 400–600 km. The horizontal wind velocity in these vortices can achieve values of 15–20 m/s in the course of time.

scholarly journals A new module for the tracking of radar-derived precipitation with model-derived winds

2007 ◽  
Vol 10 ◽  
pp. 77-83 ◽  
Author(s):  
T. Winterrath ◽  
W. Rosenow
Keyword(s):  
Wind Field ◽  
Lead Time ◽  
Weather Prediction ◽  
Dynamical Evolution ◽  
Linear Displacement ◽  
Wind Data ◽  
Horizontal Wind ◽  
Time Range ◽  
Wind Fields ◽  
Precipitation Field

Abstract. A new approach for the nowcasting of precipitation has been developed at the German Weather Service combining extrapolation techniques and Numerical Weather Prediction (NWP) for a lead time range of several hours. Radar-derived precipitation fields serve as input data for a tracking algorithm using model-derived wind data. The composite precipitation field is derived from the precipitation scans which are performed every five minutes at the 16 German radar stations. The data are corrected from clutter and shading effects. The tracking of this radar-derived precipitation field is performed using the temporally and spatially resolved horizontal wind fields at different pressure levels provided by the Local Model Europe (LME). The optimal wind field is derived from minimization of the least-squares difference between a linear combination of model wind data from different pressure levels and the linear displacement vectors calculated via pattern recognition from previous radar measurements. An area-preserving displacement of the precipitation fields is realized by eliminating the wind field divergence and by omitting the dynamical evolution of the precipitation fields. Advection is performed using the fourth-order Bott scheme. Forecasted data comprise precipitation rates for every five minutes lead time as well as hourly sums of precipitation. The verification of a case study's results against radar precipitation measurements lead to a mean Equitable Threat Score (ETS) of 70%, 46%, and 38% for the first, second, and third forecast hour, respectively.

A Modeling Study of a Low-Level Jet along the Yun-Gui Plateau in South China

2016 ◽  
Vol 55 (1) ◽  
pp. 41-60 ◽  
Author(s):  
Ming-Yang He ◽  
Hong-Bo Liu ◽  
Bin Wang ◽  
Da-Lin Zhang
Keyword(s):  
South China ◽  
Large Scale ◽  
Model Simulation ◽  
Three Dimensional ◽  
Radiative Heating ◽  
Horizontal Wind ◽  
Maximum Speed ◽  
Pressure System ◽  
Low Level ◽  
Low Level Jet

AbstractIn this study, the three-dimensional structures and diurnal evolution of a typical low-level jet (LLJ) with a maximum speed of 24 m s−1 occurring in the 850–800-hPa layer are examined using both large-scale analysis and a high-resolution model simulation. The LLJ occurred on the eastern foothills of the Yun-Gui Plateau in south China from 1400 LST 29 June to 1400 LST 30 June 2003. The effects of surface radiative heating, topography, and latent heat release on the development of the LLJ case are also studied. Results show that a western Pacific Ocean subtropical high and a low pressure system on the respective southeast and northwest sides of the LLJ provide a favorable large-scale mean pressure pattern for the LLJ development. The LLJ reaches its peak intensity at 850 hPa near 0200 LST with wind directions veering from southerly before sunset to southwesterly at midnight. A hodograph at the LLJ core shows a complete diurnal cycle of the horizontal wind with a radius of 5.5 m s−1. It is found that in an LLJ coordinates system the along-LLJ geostrophic component regulates the distribution and 65% of the intensity of LLJ, whereas the ageostrophic component contributes to the clockwise rotation, thus leading to the formation and weakening of the LLJ during night- and daytime, respectively. Numerical sensitivity experiments confirm the surface radiative heating as the key factor in determining the formation of the nocturnal LLJ. The existence of the Yun-Gui Plateau, and the downstream condensational heating along the mei-yu front play secondary roles in the LLJ formation.

scholarly journals Wind Field Synthesis for Animating Wind-induced Vibration

2011 ◽  
Vol 10 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Oyundolgor Khorloo ◽  
Zorig Gunjee ◽  
Batjargal Sosorbaram ◽  
Norishige Chiba
Keyword(s):  
Wind Field ◽  
Structural Engineering ◽  
Computational Cost ◽  
Three Dimensional ◽  
Wind Fields ◽  
Simple Method ◽  
Turbulent Wind ◽  
Key Characteristics ◽  
Induced Motion ◽  
Wind Induced Vibration

We present a simple method to generate three-dimensional frozen and non-frozen turbulent wind fields for use in the animation of wind-induced motion. Our approach uses 1/f^_ noise to match the characteristics of natural wind. By employing a noise-based approach, the complexity as well as computational cost is reduced. Additionally, by considering key characteristics of actual wind that are applied in the structural engineering field, our proposed method is able to produce plausible results in outdoor wind field simulations. In this paper, we describe the implementation results of our proposed method and compare them with other existing approaches used to construct turbulent wind fields. The implementation and visualization are carried out for both two- and three-dimensional scenarios and compared with the results of other well-known methods.

Unusually Long Duration, Multiple-Doppler Radar Observations of a Front in a Convective Boundary Layer

2007 ◽  
Vol 135 (1) ◽  
pp. 93-117 ◽  
Author(s):  
John R. Stonitsch ◽  
Paul M. Markowski
Keyword(s):  
Boundary Layer ◽  
Density Gradient ◽  
Doppler Radar ◽  
Deep Convection ◽  
Three Dimensional ◽  
Horizontal Wind ◽  
Normal Density ◽  
Wind Fields ◽  
Convective Boundary ◽  
Convection Initiation

Abstract Dual-Doppler observations acquired by a network of mobile radars deployed in the Oklahoma panhandle on 3 June 2002 are used to document the kinematic structure and evolution of a front. The data were collected during the International H2O Project on a mission to study the initiation of deep convection. Synchronized scanning allowed for the synthesis of three-dimensional wind fields for nearly 5.5 h of the 1557–0000 UTC period. The front initially moved southward as a cold front, stalled, and later retreated northward as a warm front. Deep convection failed to be initiated along the front. In situ thermodynamic measurements obtained by a mobile mesonet were used to document changes in the density gradient at the surface. This paper examines the relationships among the changes in baroclinity, the thermally direct frontal circulation, updraft intensity, alongfront updraft variability, and the intensity of vortices along the front. Increases in the front-normal density gradient tended to be associated with increases in the thermally direct frontal circulation, as expected. Increases in the front-normal density gradient were also associated with an increase in the tilt of the frontal updraft as well as an increase in the contiguity of the updraft along the front, termed the “slabularity.” During periods when the front-normal density gradient and associated thermally direct frontal circulation were weak, the kinematic fields were dominated by boundary layer convection and the slabularity of the front was reduced. Intensification of the front-normal density gradient was accompanied by an increase in the horizontal wind shear and the intensity of vortices that were observed along the front. The vortices modulated the vertical velocity field along the front and therefore the slabularity, too. Thus, although the slabularity was a strong function of the strength of the thermally direct frontal circulation, the slabularity appeared to be modified by vortices in complex ways. Possible implications of the observations for convection initiation are also discussed, particularly with respect to updraft tilt and slabularity.

Sign in / Sign up

Export Citation Format

Share Document