scholarly journals Spectral Analysis of Gravity Waves from Near Space High-Resolution Balloon Data in Northwest China

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 133 ◽  
Author(s):  
Yang He ◽  
Zheng Sheng ◽  
Mingyuan He
Keyword(s):  
Spectral Analysis ◽  
High Resolution ◽  
Wind Field ◽  
Spectral Characteristics ◽  
Three Dimensional ◽  
Northwest China ◽  
Radiosonde Data ◽  
Horizontal Wind ◽  
Height Range ◽  
Near Space

Using a set of near space high-resolution balloon data released in Hami, Xinjiang, we explored the spectral characteristics of temperature fluctuations and three-dimensional wind field fluctuations. As different from previous studies, which were based on radiosondes, we have increased the height range of spectral analysis to the stratosphere (38 km), which can explore the variation of spectral features with altitude, and can analyze higher wavenumber regions. The results show that horizontal wind field disturbances are isotropic, meridional and zonal winds have relatively consistent spectral structures, while vertical wind fluctuations have completely different spectral structures, which cannot be explained by the existing “universal spectrum” theory. The observed spectrum of horizontal wind field can be explained well by the “wind-shifting” theory. The ratio of spectral kinetic energy to potential energy is approximately constant only in the high wavenumber region but it varies at different height intervals. This study is a necessary extension of the observation for the characteristics of the vertical wavenumber spectrum in northwestern China, and it is also an experimental observation of spectral characteristics using radiosonde data at higher altitudes.

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 Vertical wavenumber spectra of three-dimensional winds revealed by radiosonde observations at midlatitude

2017 ◽  
Vol 35 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Shao Dong Zhang ◽  
Chun Ming Huang ◽  
Kai Ming Huang ◽  
Ye Hui Zhang ◽  
Yun Gong ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Meridional Wind ◽  
Vertical Wind ◽  
Radiosonde Data ◽  
Horizontal Wind ◽  
Spectral Structure ◽  
Wind Fluctuation ◽  
The Mean

Abstract. By applying 12-year (1998–2009) radiosonde data over a midlatitude station, we studied the vertical wavenumber spectra of three-dimensional wind fluctuations. The horizontal wind spectra in the lower stratosphere coincide well with the well-known universal spectra, with mean spectral slopes of −2.91 ± 0.09 and −2.99 ± 0.09 for the zonal and meridional wind spectra, respectively, while the mean slopes in the troposphere are −2.64 ± 0.07 and −2.70  ±  0.06, respectively, which are systematically less negative than the canonical slope of −3. In both the troposphere and lower stratosphere, the spectral amplitudes (slopes) of the horizontal wind spectra are larger (less negative) in winter, and they are larger (less negative) in the troposphere than in the lower stratosphere. Moreover, we present the first statistical results of vertical wind fluctuation spectra, which revealed a very shallow spectral structure, with mean slopes of −0.58 ± 0.06 and −0.23 ± 0.05 in the troposphere and lower stratosphere, respectively. Such a shallow vertical wind fluctuation spectrum is considerably robust. Different from the horizontal wind spectrum, the slopes of the vertical wind spectra in both the troposphere and lower stratosphere are less negative in summer. The height variation of vertical wind spectrum amplitude is also different from that of the horizontal wind spectrum, with a larger amplitude in the lower stratosphere. These evident differences between the horizontal and vertical wind spectra strongly suggest they should obey different spectral laws. Quantitative comparisons with various theoretical models show that no existing spectral theories can comprehensively explain the observed three-dimensional wind spectra, indicating that the spectral features of atmospheric fluctuations are far from fully understood.

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.

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 The First Observation of Turbulence in Northwestern China by a Near-Space High-Resolution Balloon Sensor

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 677 ◽  
Author(s):  
Yang He ◽  
Zheng Sheng ◽  
Mingyuan He
Keyword(s):  
Turbulence Intensity ◽  
Northwest China ◽  
Energy Dissipation Rate ◽  
Radiosonde Data ◽  
Turbulence Scale ◽  
Near Space ◽  
Internal Mixing ◽  
New Type ◽  
Instrument Noise ◽  
Scale Turbulence

Based on a new type of sensor mounted on a near-space balloon released in Hami, Xinjiang, the Thorpe method was used to analyze turbulence. The method was applied for the first time to northwest China (the mid-latitude region), and almost no radiosonde data above 40 km have been used to study turbulence hitherto. The feasibility of analyzing turbulence characteristics using radiosonde data based on the Beidou positioning system by the Thorpe method was thus verified. The distribution characteristics of turbulence scale, turbulence intensity, and turbulence kinetic energy dissipation rate, and the turbulence diffusion coefficient, were analyzed and discussed. The relationship between turbulence fraction, turbulence intensity, and stratified instability was also investigated. The results show that over 35 km, the influence of instrument noise on turbulence detection is significantly enhanced, which lead to an overestimation of turbulence in that region. The turbulence fraction was defined to reflect the degree of turbulence internal mixing, which is closely related to atmospheric instability. It was found that when the turbulence fraction reached 60%–80%, the turbulence reached its strongest intensity, and when the turbulence fraction exceeded 80%, the turbulence could not be maintained and began to decay.

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.

The Dynamic Response of the Hurricane Wind Field to Spiral Rainband Heating

2010 ◽  
Vol 67 (6) ◽  
pp. 1779-1805 ◽  
Author(s):  
Yumin Moon ◽  
David S. Nolan
Keyword(s):  
Wind Field ◽  
Diabatic Heating ◽  
Three Dimensional ◽  
Secondary Circulation ◽  
Horizontal Wind ◽  
Wind Maximum ◽  
Hurricane Wind ◽  
Spiral Rainband ◽  
Anelastic Equations ◽  
Spiral Rainbands

Abstract The response of the hurricane wind field to spiral rainband heating is examined by using a three-dimensional, nonhydrostatic, linear model of the vortex–anelastic equations. Diabatic heat sources, which are designed in accordance with previous observations of spiral rainbands, are made to rotate with the flow around the hurricane-like wind field of a balanced, axisymmetric vortex. Common kinematic features are recovered, such as the overturning secondary circulation, descending midlevel radial inflow, and cyclonically accelerated tangential flow on the radially outward side of spiral rainbands. Comparison of the responses to the purely convective and stratiform rainbands indicates that the overturning secondary circulation is mostly due to the convective part of the rainband and is stronger in the upwind region, while midlevel radial inflow descending to the surface is due to the stratiform characteristics of the rainband and is stronger in the downwind region. The secondary horizontal wind maximum is exhibited in both convective and stratiform parts of the rainband, but it tends to be stronger in the downwind region. The results indicate that the primary effects of rainbands on the hurricane wind field are caused by the direct response to diabatic heating in convection embedded in them and that the structure of the diabatic heating is primarily responsible for their unique kinematic structures. Sensitivity tests confirm the robustness of the results. In addition, the response of the hurricane wind field to the rainband heating is, in the linear limit, the sum of the asymmetric potential vorticity and symmetric transverse circulations.

High Resolution Microscopy of Multi-Layered Biological Crystals

1982 ◽  
Vol 40 ◽  
pp. 80-83
Author(s):  
H.A. Cohen ◽  
T.W. Jeng ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Low Dose ◽  
Three Dimensional ◽  
Data Interpretation ◽  
Two Dimensional ◽  
Biological Objects ◽  
Density Maps ◽  
Density Map ◽  
Complex Crystal ◽  
High Resolution Microscopy

This tutorial will discuss the methodology of low dose electron diffraction and imaging of crystalline biological objects, the problems of data interpretation for two-dimensional projected density maps of glucose embedded protein crystals, the factors to be considered in combining tilt data from three-dimensional crystals, and finally, the prospects of achieving a high resolution three-dimensional density map of a biological crystal. This methodology will be illustrated using two proteins under investigation in our laboratory, the T4 DNA helix destabilizing protein gp32*I and the crotoxin complex crystal.

Electron crystallographic determination of the 3-D structure of staurolite at atomic resolution

1991 ◽  
Vol 49 ◽  
pp. 540-541
Author(s):  
Kenneth H. Downing ◽  
Hu Meisheng ◽  
Hans-Rudolf Went ◽  
Michael A. O'Keefe
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
Atomic Resolution ◽  
Dimensional Structure ◽  
Structure Information ◽  
Resolution Electron ◽  
Scattering Effects ◽  
High Resolution Images ◽  
Effects Of Radiation

With current advances in electron microscope design, high resolution electron microscopy has become routine, and point resolutions of better than 2Å have been obtained in images of many inorganic crystals. Although this resolution is sufficient to resolve interatomic spacings, interpretation generally requires comparison of experimental images with calculations. Since the images are two-dimensional representations of projections of the full three-dimensional structure, information is invariably lost in the overlapping images of atoms at various heights. The technique of electron crystallography, in which information from several views of a crystal is combined, has been developed to obtain three-dimensional information on proteins. The resolution in images of proteins is severely limited by effects of radiation damage. In principle, atomic-resolution, 3D reconstructions should be obtainable from specimens that are resistant to damage. The most serious problem would appear to be in obtaining high-resolution images from areas that are thin enough that dynamical scattering effects can be ignored.

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