共查询到20条相似文献，搜索用时 15 毫秒
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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
3.
M. A. Lokoshchenko 《Russian Meteorology and Hydrology》2007,32(1):35-42
Features of diurnal and annual cycles and of seasonal changes of temperature stratification in the lower 800-m air layer over Moscow are discussed on the basis of analysis of long-term data of acoustic (sodar) observations at Moscow State University (MSU). Of about 34 000 separate hours of height-time sweep of echo signal during 1988–2003, refined estimates are presented of occurrence frequencies of surface and elevated inversions, unstable stratification, etc., in Moscow. On the basis of long series of hourly sodar data and surface weather observations at MSU, special features of temperature stratification are considered under extremely low and high values of air temperature, wind speed, and relative humidity. A review is presented of existing data on temperature stratification in central Russia for the whole period of aerological observations; results of acoustic sounding are compared against the data obtained using other techniques. 相似文献
4.
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
5.
Evidence of Organized Large Eddies by Ground-Based Doppler Lidar, Sonic Anemometer and Sodar 总被引：3，自引：0，他引：3
Philippe Drobinski Robert a. Brown Pierre H. Flamant Jacques Pelon 《Boundary-Layer Meteorology》1998,88(3):343-361
In an experiment investigating the planetary boundary layer (PBL) wind and temperature fields, and PBL inversion height recorded by various instruments, the results reveal the presence of organized large eddies (OLE) or rolls. The measurements by lidars, anemometers, soundings and sodar gave an overview of the characteristics of the rolls and sources of energy production that maintain them. The experimental results obtained on two consecutive days are compared to model outputs. The agreement is excellent, showing that thermal stratification and wind shear are important factors in the structure and dynamics of OLE. A heterodyne Doppler lidar (HDL) is shown to be a useful tool in the study of OLE. 相似文献
6.
S. Reid 《Boundary-Layer Meteorology》2003,108(2):305-314
A Remtech PA2 sodar has been operated at two hilltop sites in New Zealand overperiods of several months. Data were lost predominantly in periods of high windspeed. Data obtained from the sodar have been used to obtain typical wind profilesat the sites for the cross-ridge direction for neutral stratification and have beencompared with model profiles. 相似文献
7.
Summary Application of acoustic sounders (sodars) to study the atmospheric boundary layer (ABL) began in the early 1970s. During the last two decades the scope of sodars applications enlarged considerably. The proceedings of eleven symposia of the International Society for Remote Acoustic Sensing of the Atmosphere and Oceans (ISARS) are a unique collection of papers, where all directions of the sodar use since 1981 are presented. In this paper, a review of sodar applications to atmospheric research is presented based on materials published in these proceedings in the following fields: conditions of microwave and light propagation; regional climatology of the ABL; air pollution meteorology and weather forecast; mesoscale phenomena under stable and unstable stratification; micrometeorology; peculiarities of the ABL in remote and complex terrain. 相似文献
8.
Summary This paper presents a brief synopsis of past, current and anticipated progress and problems in the use of acoustic remote
sensing for basic and applied research of the lower atmosphere. The potential and reality of the sodar for determination of
meteorological parameters and turbulence characteristics is discussed. Sodars’ place alongside other ground-based remote sensors,
including radar wind profilers, radioacoustic sounding systems (RASS) and lidars, is elucidated. Areas of atmospheric research
where Doppler sodar has certain advantages are described such as cost, sensitivity, spatial and temporal resolution and surface
layer measurements. The use of sodar in networks of integrated radar/RASS systems designed to supply uninterrupted monitoring
of atmospheric parameters for improvements in forecasts of weather and air quality is demonstrated.
The special potential role of sodar in education and training of specialists is suggested to aid in developing and using new
methods of atmospheric measurements and meeting the requirements of modern environmental science.
A number of problems are formulated whose solution would favor further advancement of acoustic remote sensing in integrated
systems for remote monitoring of the atmospheric boundary layer.
Received November 23, 1998 Revised January 29, 1999 相似文献
9.
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
10.
Results of simultaneous balloon and acoustic sounding in the lower troposphere (in the surface layer up to 800 m) carried out in Velikie Luki in May–June 2002 jointly by the Moscow State University (MSU) and Central Aerological Observatory (CAO) are discussed. During the experiment, the tethered (captive) balloon for measuring air temperature and ozone partial pressure was ascended and descended 15 times. Simultaneously, gradient measurements were performed at a 4-m tower. During the intervals between ascents, the temperature stratification was determined by using the Ekho-1 sodar data. A dominating influence of temperature stratification and of some weather events on the ozone distribution with altitude is shown. In case of unstable stratification, its partial pressure is almost unchanged within the entire lower troposphere; in case of surface inversion, the ozone decrease is observed near the surface. In case of elevated inversion the ozone partial pressure is almost the same both below inversion and above it; in the layer of the inversion itself, it increases spasmodically with the altitude. Synoptic conditions largely influence the stratification regime: under conditions of the Arctic air mass, the thermal convection is observed more often and surface inversions are observed more rarely than when the local mass dominates. Artificial dynamic mixing can lead to the surface inversion dissipation in several minutes. 相似文献
11.
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
12.
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
13.
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
14.
P. Martano D. Cava G. Mastrantonio S. Argentini A. Viola 《Boundary-Layer Meteorology》2005,115(1):85-103
Nocturnal convection, originating in a well-mixed marine cloud-topped boundary layer, advected onshore, was observed using a Doppler sodar on the Tyrrhenian coast in Italy. The horizontal and vertical dimensions of the downdrafts were evaluated. The oscillation frequency triggered by the downdrafts at the inversion layer, derived from the harmonic analysis of the sodar measured vertical velocity (w), is compared with the Brunt-Vaisala frequency, obtained from the rawinsonde temperature profile. A similarity function for the 2w vertical profile was used to fit the sodar experimental data and to retrieve the depth of the mixing layer and the sensible heat flux at the top of the cloud layer. The results are in agreement with the convection layer depth observed in the sodar echoes facsimile record, and with the energy budget evaluated at the top of the cloud layer using the rawinsonde profiles. 相似文献
15.
Stefania Argentini Giangiuseppe Mastrantonio Igor Petenko Ilaria Pietroni Angelo Viola 《Boundary-Layer Meteorology》2012,143(1):177-188
Measurements in the atmospheric surface layer are generally made with point sensors located in the first few tens of metres.
In most cases, however, these measurements are not representative of the whole surface layer. Standard Doppler sodars allow
a continuous display of the turbulent thermal structure and wind profiles in the boundary layer up to 1000 m, with a few points,
if any, in the surface layer. To overcome these limitations a new sodar configuration is proposed that allows for a higher
resolution in the surface layer. Because of its capabilities (echo recording starting at 2 m, echo intensity vertical resolution
of approximately 2 m, temporal resolution of 1 s) this sodar is called the surface-layer mini-sodar (SLM-sodar). Features
and capabilities of the SLM-sodar are described and compared with the sodar. The comparison of the thermal vertical structure
given by the SLM-sodar and the sodar provides evidence that, in most cases, the surface layer presents a level of complexity
comparable to that of the entire boundary layer. Considering its high vertical resolution, the SLM-sodar is a promising system
for the study of the nocturnal surface layer. The nocturnal SLM-sodar measurements have shown that, depending on wind speed,
the structure of the surface layer may change substantially within a short time period. At night, when the wind speed is greater
than 3 m s−1, mechanical mixing destroys the wavy structure present in the nocturnal layer. Sonic anemometer measurements have shown that,
in such cases, also the sensible heat flux varies with height, reaching a peak in correspondence with the wind speed peak.
Under these conditions the assumption of horizontal homogeneity of the surface layer and the choice of the averaging time
need to be carefully treated. 相似文献
16.
The technical characteristics of the CRPE minisodar are described and it is compared with the classical Doppler sodar.The results of surface layer analysis are given and simple methods are demonstrated for estimating the sensible heat flux and friction velocity in the surface layer.The system is shown to be feasible for working on the birth of gravity waves and the analysis of wind profile and turbulence evolution.Hydrometeorological studies with the minisodar are discussed with special emphasis on the problem of the relationship between wind shear in the surface layer and hydrometeor fall speed.In the conclusion, the prospective uses of the minisodar are presented. 相似文献
17.
The question of estimating the height of the stable boundary layer (SBL) based on digitalized vertical profiles of sodar signal intensity has been re-examined. A simple one-dimensional numerical boundary-layer model is used to compute vertical profiles of the temperature structure parameterC
T
2
. It is shown that especially at the beginning of the night (when stratification is weak) one can not expect any significant profile structure in the upper part of the SBL if its depth is determined in terms of common turbulent height scales. From this it is concluded that the SBL-height will be underestimated early in the night when derived from the maximum gradient in the signal intensity profiles. Later in the night in contrast, the computations often show elevated maxima or even zones with reduced, and above them enhanced, vertical gradients ofC
T
2
, from which a SBL-height can be deduced that compares well with other common height scales. The computed profiles ofC
T
2
are shown to be in qualitative agreement with observed profiles of sodar signal intensity for several analysed cases from the HAPEX-MOBILHY experiment.Comparing different SBL-depth scales with sodar observations, it is demonstrated that most of them are often closely related to a sodar-derived SBL-height only during certain phases of the night. Thus the sodar-SBL-height can, after a transition period, be perhaps associated with the lower turbulent layer of the growing surface inversion during the first part and with the height of the low-level wind maximum during the second part of the night. 相似文献
18.
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
19.
Profile data from simultaneous sodar and tethered balloon measurements have been analyzed with respect to the complex structure of the atmospheric boundary layer in the Upper Rhine Valley. Special attention was focused on ozone concentration profiles measured with a novel lightweight ozone sensor at the balloon. In general, good agreement was found between the signature of the ozone concentration profiles and special features of the backscattered sound intensity profiles. This allows reliable estimation of the mixing height from the sodar data even in a complex stable ABL, except for very shallow mixing layers (below about 75 m), which could not be detected by the sodar. 相似文献
20.
S.P. Singal 《Atmospheric Research》1986,20(2-4)
Radio wave propagation of the decimetric and centimetric waves depends to a large extent on the boundary layer meteorological conditions which give rise to severe fadings, very often due to multipath propagation. Sodar is one of the inexpensive remote sensing techniques which can be employed to probe the boundary layer structure.In the paper a historical perspective has been given of the simultaneously conducted studies on radio waves and sodar at various places. The radio meteorological information needed for propagation studies has been clearly spelt out and conditions of a ray path especially in the presence of a ducting layer have been defined as giving rise to fading or signal enhancement conditions. Finally the potential of the sodar studies to obtain information about the boundary layer phenomena has been stressed, clearly spelling out the use of acoustic sounding in radio wave propagation studies. 相似文献