共查询到20条相似文献，搜索用时 36 毫秒
1.
Zhou Mingyu Chen Jingnan Li Shiming Zheng Yueming Su Lirong L&#;Naiping 《Acta Meteorologica Sinica》1991,5(3):331-341
A Doppler sodar system controlled by microcomputer is described in this paper. The sodar was usedto detect the vertical distribution of wind and temperature stratification in the atmospheric boundary layer.The detecting results show that at night the vertical distribution of wind is very complicated, which can appearas a structure of two or three layers. In nocturnal atmospheric boundary layer sometimes there exists verythin layer in multi-layer inversion and it can be retained for a long time. 相似文献
2.
V. P. Yushkov 《Russian Meteorology and Hydrology》2013,38(12):818-827
The wind speed shear in the case of stable stratification in the linear part of the profile spreading high above the surface layer of constant flows is studied using the data of long-term sodar measurements in the atmospheric boundary layer. The wind speed shear in this part remains almost invariable during several hours at the significant change in parameters of the Monin-Obukhov theory. The length of this linear part can be associated with the layer of the critical Richardson number. In the case of the pronounced temperature inversion (with the positive gradient of more than 1°C per 100 m), the wind speed profile is close to the linear function in the most part of the nocturnal mixing layer. Proposed is a scale characterizing the height of the surface layer of constant flows. 相似文献
3.
Igor Petenko Giangiuseppe Mastrantonio Angelo Viola Stefania Argentini Ilaria Pietroni 《Boundary-Layer Meteorology》2012,143(1):125-141
Some characteristics of wavelike motions in the atmospheric boundary layer observed by sodar are considered. In an experiment
carried out in February 1993 in Milan, Italy, Doppler sodar measurements were accompanied by in situ measurements of temperature
and wind velocity vertical profiles using a tethered balloon up to 600 m. The oscillations of elevated wavy layers containing
intense thermal turbulence, usually associated with temperature-inversion zones, were studied by using correlation and spectral
analysis methods. The statistics of the occurrence of wavelike and temperature-inversion events are presented. The height
distributions of Brunt–Vaisala frequency and wind shear and their correlation within elevated inversion layers were determined,
with a strong correlation observed between the drift rate of the wavy layers and the vertical velocity measured by Doppler
sodar inside these layers. Spectral analysis showed similarities regarding their frequency characteristics. The phase speed
and propagation direction of waves were estimated from the time delay of the signals at three antennae to provide estimates
of wavelength. Moreover, wavelengths were estimated from the intrinsic frequency obtained from sodar measurements of the Doppler
vertical velocity and oscillations of wavy turbulent layers. The two wavelength estimates are in good agreement. 相似文献
4.
S. Casadio A. Di Sarra G. Fiocco D. Fuà F. Lena M. P. Rao 《Boundary-Layer Meteorology》1996,79(4):375-391
Convective plume patterns, characteristic of clear sky and light wind daytime boundary layers over land, were observed for two nights with a tri-axial Doppler sodar operated in the central area of Rome during the summer of 1994. An urban heat island effect, combined with a continuation of a breeze from the sea late into night during both days, is believed to be responsible for the observed nocturnal convection. Estimates of the surface heat flux and the vertical velocity scaling parameter are obtained from profiles of vertical velocity variance, and the Raman lidar water vapor measurements are used to obtain the humidity scaling parameter. Convective scaling results for vertical wind and humidity fairly agree with the results of other experiments and models. On the basis of available measurements, it appears that mixed-layer similarity formulations used to characterize the daytime convective boundary layer over horizontally homogeneous surfaces can also be applied to the nocturnal urban boundary layer during periods of reasonable convective activity. 相似文献
5.
Summary ?This paper describes the configuration of measurement systems operated continuously at the Meteorological Observatory Lindenberg
with the aim of constructing combined profiles of wind and temperature – so-called composite profiles – covering the boundary
layer with high temporal and vertical resolution. This is required for the forcing of a micro-α-scale model in order to simulate
the atmospheric boundary layer structure over a heterogeneous landscape during the LITFASS-98 experiment. The problems of
combining measurements of different remote sensing and in-situ systems are briefly discussed. Although the measuring range
of individual remote sensing systems is variable, the height coverage of wind and temperature profile measurements by sodar/RASS
and two wind profiler radar/RASS complement each other very well. Using a simple merging procedure composite wind and temperature
profiles have been synthesized based on radiosonde, windprofiler/RASS, sodar/RASS and tower measurements. Time-height cross
sections of hourly composite profiles show considerably more details of the boundary layer structure than simple radiosonde
interpolation due to the higher sampling frequency, higher vertical resolution and increased accuracy at the lower levels.
Finally some qualifications of the formulated algorithm are suggested for future application.
Received June 18, 2001; revised May 30, 2002; accepted June 6, 2002 相似文献
6.
U. Corsmeier M. Kossmann N. Kalthoff A. Sturman 《Meteorology and Atmospheric Physics》2006,91(1-4):129-148
Summary In July 2000 (South Hemisphere winter), the Christchurch Air Pollution Study (CAPS2000) was performed in order to establish a comprehensive data set for documentation and analysis of nocturnal winter
smog conditions in the Christchurch area. Field activities included meteorological surface measurements, tethersonde ascents,
radiosoundings and sodar measurements. Air pollutant monitoring included CO, NO, NOx, O3, PM10, PM2.5, and black carbon measurements near the surface, and for the first time vertical CO-profile measurements in the nocturnal
boundary layer up to 100 m height.
A prerequisite for nocturnal winter smog conditions is the evolution of stable stratification before the evening traffic and
domestic heating reach a maximum. When stable stratification persists during domestic heating and road traffic in the morning,
a second pronounced maximum of air pollutants evolves at around 0800 NZST. The meteorological measurements also revealed a
complex nocturnal surface wind field, dominated by drainage winds from the Port Hills to the south and from the Canterbury
Plains to the west of the Christchurch city area. A resulting convergence zone forms over the central parts of the city and
is accompanied by low wind speeds. The position of the convergence zone varies during the night. These low winds over the
city centre, in conjunction with stable stratification, favour the accumulation of air pollutants in the lowest tens of metres.
The nocturnal winter smog situation ends with the erosion of the surface inversion at about 1100 NZST. It is shown from analysis
of the vertical CO profiles that the level of air pollution in the Christchurch area depends on the height of the stable nocturnal
boundary layer, which itself is governed by variations in the local wind systems. 相似文献
7.
Summary A combination of low frequency sodar, radar wind profiler and in-situ balloon-borne measurements of temperature and water vapor have been used to investigate the structure of elevated stratified layers within the transition layer above the nocturnal boundary layer during the Vertical Transport and Mixing Field Campaign in Salt Lake City Utah, during October, 2000. Elevated layers determined from sodar and radar vertical time sections were penetrated with a balloon-born instrument package to determine the fine scale temperature and moisture structure of the layers. As expected a potential temperature increase was found in the upper half of the layers; however the magnitude was considerably smaller than found above the daytime well-mixed layer and the vertical distance of the increase was quite variable. Mixing ratio, in the mean was found to have a relative maximum in the lower portion of the layers. It was found that the potential temperature within the layers decreased with time relative to background values, regardless of whether the layer descended or ascended. 相似文献
8.
In this paper, measurements of the first 150 m of the atmospheric boundary layer obtained by a high-frequency acoustic mini-sounder are compared with measurements obtained by a full complement of instruments including sonic anemometers mounted on the Boulder Atmospheric Observatory tower. The acoustic mini-sounder, starting as low as 6 m from the ground, measures in the monostatic mode the profiles of the vertical wind speed, w, and of the temperature structure parameter, C T 2 with enhanced height resolution of the order of 1 m and time resolution of the order of 30 s. The results of the comparison show that the high-frequency mini-sounder is an effective atmospheric boundary-layer profiler that is also portable and relatively inexpensive. Measurements of the spectrum of C T 2 are presented that provide information on the local isotropy of the temperature field. Statistics of the variability of C T 2 in both stable and unstable conditions are also given. The sounder's capabilities are further demonstrated by some detailed observations of the structure and time evolution of a thermal plume root at noon and of a nocturnal, stably stratified layer in which a dynamic instability develops. The plume starts at a height of less than 5 m, possesses substantial internal structure, and includes vertical velocities in excess of 2 m s-1. 相似文献
9.
M. A. Novitskii D. E. Gaitandzhiev N. F. Mazurin M. K. Matskevich 《Russian Meteorology and Hydrology》2011,36(9):580-589
Turbulence characteristics in the surface layer of the coastal area of Akhtopol (Bulgaria) under conditions of the breeze
circulation are measured. The measurements were carried out at the level of 4.5 m by means of three-component ultrasonic anemometer.
To estimate the wind regime in the atmospheric boundary layer, the sodar data and synoptic charts were used. All turbulent
characteristics except the correlation coefficient of the friction flow have an appreciable daily course in the case of the
sea breeze. In the frontal zone, some characteristics demonstrate sometimes short-term variations of their numerical values.
The sea-land front of the breeze circulation is effectively detected from the measurements of wind speed, wind direction,
and temperature in the surface layer. It is also possible to judge about the breeze circulation type and turbulence structure
in this layer on the basis of these measurements. 相似文献
10.
Giampietro Casasanta Ilaria Pietroni Igor Petenko Stefania Argentini 《Boundary-Layer Meteorology》2014,151(3):597-608
The mixing-layer height is estimated using measurements from a high resolution surface-layer sodar run at the French-Italian station of Concordia at Dome C, Antarctica during the summer 2011–2012. The temporal and spatial resolution of the sodar allows the monitoring of the mixing-layer evolution during the whole diurnal cycle, i.e. a very shallow nocturnal boundary layer followed by a typical daytime growth. The behaviour of the summer mixing-layer height, variable between about 10- and 300 m, is analyzed as a function of the mean and turbulent structure of the boundary layer. Focusing on convective cases only, the retrieved values are compared with those calculated using a one-dimensional prognostic equation. The role of subsidence is examined and discussed. We show that the agreement between modelled and experimental values significantly increases if the subsidence is not kept fixed during the day. A simple diagnostic equation, which depends on the time-averaged integral of the near-surface turbulent heat flux, the background static stability and the buoyancy parameter, is proposed and evaluated. The diagnostic relation performance is comparable to that of the more sophisticated prognostic model. 相似文献
11.
M. A. Novitskii L. K. Kulizhnikova O. Yu. Kalinicheva D. Gaitandzhiev D. Barantiev E. Bachvarova K. Krysteva 《Russian Meteorology and Hydrology》2012,37(3):159-164
The characteristics of wind speed and wind direction in the boundary atmospheric layer measured at the meteorological station
in Akhtopol (Bulgaria) are presented. The measurements were carried out with the Scintec sodar and MK-15 automatic meteorological
station. The sodar measurement data on wind parameters at different heights in different months are presented as well as the
frequency of inshore and offshore wind directions, that enables to trace the intensity of the breeze circulation. The frequency
of calms and wind speeds at the heights of 50, 100, and 200 m according to gradations for different months and the probability
of wind of various speeds depending on the direction are also given. The breeze front characteristics in June–September of
2009 are computed from the speed and direction of surface wind measured with the acoustic anemometer of MK-15 complex. 相似文献
12.
定量测量声雷达回波强度可以导出大气温度结构系数（Ct 2）和速度结构系数（Cv2）。文章简要回顾和评述了过去的工作，并讨论了逾量衰减、风和湍流等因素对该测量的影响。研究表明:逾量衰减主要是由速度场的不均匀性所造成。其次，风场也有不可忽视的衰减作用，在风速达10 m/s时，引起的衰减达50%以上。最后给出了改进后的声雷达方程和反演Ct2和Cv2的方法。初步的试验结果对理论的应用是支持的。 相似文献
13.
Sodar performance and preliminary results after one year of measurements at Adelie land coast, east Antarctica 总被引：1，自引：0，他引：1
S. Argentini G. Mastrantonio A. Viola P. Pettre G. Dargaud 《Boundary-Layer Meteorology》1996,81(1):75-103
Dumont d'Urville, on the Antarctic coast, is an area well known for the presence of strong katabatic winds blowing from the Antarctic plateau toward the sea almost all year. Since January 1993, a three-axis Doppler sodar has been operating in this area to investigate the variability of the boundary layer structure and dynamics. In this paper, the capabilities, behavior and advantages of using this ground-based remote-sensing system in Antarctica are evaluated after one year of measurements. This instrument may play an important role in boundary layer studies in remote regions where other profiling techniques (e.g., kitoons, slow ascent balloons) are difficult and expensive. All year long, except in summer when the signal-to-noise ratio was dramatically reduced by the noise of a large group of Adelie penguins, reliable measurements were available up to 900 m. The reliability of the vertical wind velocity has been checked and the influence of the local topography on the flow pattern has been evaluated. Some preliminary results regarding the statistical analysis of the horizontal and vertical velocities and an overview of the main physical processes are also shown. The statistical analysis of the wind speed shows that the wind blows from the 30 ° angular sectors centered at 90 °, 150 °, 180 °, and 0 °. The winds from 90 ° and 150 ° constitute the main local circulation and have, most of the time, the characteristics of a katabatic flow, whereas the winds blowing from 180 °, arising from the surface temperature difference between the sea and the land, are land breezes. Strong winds coming from the ocean (0 °), attributable to the inland penetration of depressions, have been observed in May, October, and November. Finally, some examples of the observed thermal structures, as depicted in the facsimile recording, are shown. 相似文献
14.
城乡过渡地带低空温度平流和边界层特征的观测分析 总被引：4，自引：0，他引：4
利用兰州河谷盆地城乡过渡区边界层观测资料,分析了该地区的温度平流和边界层特征。分析表明:(1)夜间热岛环流明显,白天则较弱;(2)夜间200m高度以下有较强的冷平流,在250～400m高度有较弱的暖平流,冷暖温度平流对测点上空边界层温度和层结变化有显著影响;(3)由声雷达确定的夜间边界层高度对应于Ri<1.0的高度,在这一高度范围内存在逆位温和强的风切变。本地区下垫面和复杂的地形导致夜间边界层高度随时间周期性地升高和降低,变化周期约3h。 相似文献
15.
In this work, the thermic structure of the atmospheric boundary layer is analyzed by means of direct measurements with radiosonde equipment, remote exploration with a three-monostatic Doppler sodar, and a boundary layer model of order one-and-a-half. Intercomparisons of radiosonde data, sodar data, and model results are made through the study of radiative nocturnal inversion, subsidence inversion, development and height of the mixing layer, and calculus of the temperature structure parameter. The ability of sodar to find the mixing layer height and to detect stable layers is enhanced when these layers are low enough. 相似文献
16.
Isidro A. Pérez M. Luisa Sánchez M. ángeles García 《Theoretical and Applied Climatology》2012,107(1-2):247-253
Temperature and wind speed profiles obtained from 3?years of radio acoustic sounding system sodar measurements at a rural site in the northern Spanish plateau were fitted to polynomial functions. Depending on the extrema of these fits, several groups of profiles were considered. Daily evolution of temperature profiles corresponded to the lower boundary layer evolution. However, wind speed profiles revealed a frequent low-level jet during the whole day. CO2 surface concentrations were analysed, and surface CO2 dilution was also considered by selection of thin canopies with variable depth, resulting in dilution rates of 7 and 18?ppm when the layer increased 100?m for the 95th percentile and temperature and wind speed profiles, respectively. 相似文献
17.
M. P. Rao Paolo Castracane Stefano Casadio Daniele Fuá Giorgio Fiocco 《Boundary-Layer Meteorology》2004,111(1):85-108
The simultaneous operation of a three-axis Doppler sodar system in the centralurban area of Rome and two similar systems in the suburban area, forming atriangle about 20 km on each side, provided evidence of solitary-type wavesin the urban boundary layer. Three events, each lasting from a few minutes toabout 30 min, and ranging in depth from the minimum range of the sodar (39 m) to over 500 m, are reported here. Two events were recognizable onall three sodar records while the third event could be observed at the urbanlocation only. Time-height acoustic echo intensity records showed no-echoregions within the wave indicating transport of trapped recirculating air.This is typical of large amplitude solitary waves. The time series plots ofsodar-derived vertical wind velocity revealed a maximum peak-to-peakvariation of about 5 m s-1 during periods of wave-associated disturbance.The vertical velocity is found to increase with height up to the top of the closedcirculation within the wave and decreases further above. The normalisedamplitude-wavelength relationship for the two events indicates that theobserved waves are close to a strongly nonlinear regime. 相似文献
18.
19.
Sodar measurements have been made at La Spezia, Italy during land- and sea-breeze conditions. The backscatter returns are discussed qualitatively, including their relation to the vertical structure of the boundary layer as revealed by vertical soundings of wind and temperature. During inversion conditions, the sodar signals may be difficult to interpret especially when there is a land breeze flowing over irregular terrain. 相似文献
20.
Impact of a sea breeze on the boundary-layer dynamics and the atmospheric stratification in a coastal area of the North Sea 总被引：1，自引：0，他引：1
Charles Talbot Patrick Augustin Céline Leroy Véronique Willart Hervé Delbarre Georgui Khomenko 《Boundary-Layer Meteorology》2007,125(1):133-154
In-situ sodar and lidar measurements were coupled with numerical simulations for studying a sea-breeze event in a flat coastal
area of the North Sea. The study’s aims included the recognition of the dynamics of a sea-breeze structure, and its effects
on the lower troposphere stratification and the three-dimensional (3D) pollutant distribution. A sea breeze was observed with
ground-based remote sensing instruments and analysed by means of numerical simulations using the 3D non-hydrostatic atmospheric
model Meso-NH. The vertical structure of the lower troposphere was experimentally determined from the lidar and sodar measurements,
while numerical simulations focused on the propagation of the sea breeze inland. The sea-breeze front, the headwind, the thermal
internal boundary layer, the gravity current and the sea-breeze circulation were observed and analysed. The development of
a late stratification was also observed by the lidar and simulated by the model, suggesting the formation of a stable multilayered
structure. The transport of passive tracers inside the sea breeze and their redistribution above the gravity current was simulated
too. Numerical modelling showed that local pollutants may travel backward to the sea above the gravity current at relatively
low speed due to the shearing between the landward gravity current and the seaward synoptic wind. Such dynamic conditions
may enhance an accumulation of pollutants above coastal industrial areas. 相似文献