共查询到19条相似文献,搜索用时 630 毫秒
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垂直散度廓线可用于推断大气垂直运动情况,垂直温度平流廓线可用于推断大气层结是否稳定,有助于预报员推断本站降水演变趋势。鉴于我国多普勒天气雷达中还没有垂直散度和温度平流廓线产品,提出了这两种产品的反演方法。首先使用分层VVP方法从雷达体扫径向速度资料中反演出雷达站上空的垂直风廓线和垂直散度廓线,然后在假设大气处于地转平衡条件下,基于温度平流与地转风随高度的变化关系,从垂直风廓线中反演出垂直温度平流廓线。以两次大范围暴雨天气过程为例,反演了雷达站上空的垂直风廓线、散度廓线和温度平流廓线,并对反演结果进行了分析。结果表明:在雷达周围有大范围降水回波的情况下,使用分层VVP方法能合理地反演出雷达站上空的垂直风廓线和散度廓线;在这种情况下,反演的垂直风廓线代表各个高度雷达有效探测范围内的平均水平风,可近似满足地转平衡条件,因此,使用热成风方程能较为合理地从垂直风廓线中反演出垂直温度平流廓线;三个反演产品的合理性可用天气学理论和天气实况来解释。 相似文献
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基于湍流散射理论,运用边界层风廓线雷达 (WPR) 联合RASS (Radio Acoustic Sounding System), GPS/PWV (Global Position System/Precipitable Water Vapor) 进行全遥感系统的大气比湿廓线反演试验,并对影响因子进行分析。利用2011年8—9月云南大理综合探测试验数据的反演结果与探空数据进行比较分析,结果表明:WPR联合探空的温度廓线和起始边界比湿 (q0) 反演大气比湿廓线,与探空大气比湿廓线相比具有相同的变化趋势,标准差为0.84 g·kg-1,误差随高度增加呈递增趋势;WPR联合RASS, GPS/PWV数据反演大气比湿廓线,与探空大气比湿廓线的标准差为0.85 g·kg-1。参加反演的数据中,折射指数结构常数Cn2与谱宽σturb2对反演影响最大,反演算法中大气折射指数梯度M符号的判断对反演精度也有较大影响。 相似文献
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本研究提出了一种在边界层风廓线雷达连续运行的降水探测时段中对降水频谱进行在线分析的新的应用方式。详细介绍了边界层风廓线雷达在线分析原理和方法。同时结合典型降水频谱个例,分析了可获得的多个潜在的气象参数和信息。并指出,该在线分析方式的实施可以使风廓线雷达的应用领域从晴空探测向降水测量拓展;有效缓解当前风廓线雷达应用存在的瓶颈问题;间接证明边界层风廓线雷达组网间距不固定的观点。文章分析说明,随着在线分析方式的推广应用,边界层风廓线雷达将成为单站精细化气象探测和预报/服务的重要工具。 相似文献
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上海TWP3型边界层风廓线雷达探测性能评估 总被引:1,自引:0,他引:1
在简述上海TWP3型风廓线雷达系统的基础上,从雷达运行情况、风数据获取率和产品资料分析3方面对该型号雷达探测性能进行评估。通过统计分析不同高度层上平均测风数据全年和逐月的数据获取率,发现TWP3风廓线雷达在3km以下具有较高的数据获取率,对于边界层的探测能力要远高于高层,且夏季的数据获取率明显高于冬季。利用风廓线雷达提供的信号噪声比SNR、垂直速度和折射率结构常数C2N等资料分析了一次弱降水探测过程,二次产品可以清晰地反映降水的始末时间,且降水期间探测高度增高2km左右。评估结果表明TWP3型边界层风廓线雷达具有较低的故障率和较好的探测性能,产品资料具有可靠性和应用价值。 相似文献
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风廓线雷达资料在天气业务中的应用现状与展望 总被引:2,自引:0,他引:2
风廓线雷达是目前我国着重规划发展的垂直风廓线探测设备,其探测资料对天气预报预警具有重要价值。本文回顾了风廓线雷达资料在灾害性天气监测和预报中的应用,阐述了业务应用中存在的主要问题和未来发展的方向。风廓线雷达探测产品能够监测不同尺度天气系统的结构和演变,估计降水相态以及雨滴谱分布的云微物理信息,其提供的高空风资料进入快速同化系统和中尺度模式可以提高预报准确率,最后介绍了风廓线雷达单站和组网资料在强对流天气监测和业务中的应用情况,为预报员通过利用风廓线雷达资料了解天气系统的中尺度信息提供了一定的参考。 相似文献
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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
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John R. Taylor Nathan J. Segal Michael R. Bradshaw David J. Low 《Meteorology and Atmospheric Physics》2013,119(3-4):197-206
Potential sonic temperature profiles from a continuous electromagnetic, pulsed acoustic, radio acoustic sounding system (RASS) were compared with profiles recorded by a commercially available temperature, relative humidity and pressure recorder mounted in a radio-controlled model motor-glider. The glider profiles covered the period of the morning transition in the lowest 200 m of an initially stably stratified boundary layer. Comparison of the profiles shows that the sonic temperature can be calculated based on the average speed of sound in the boundary layer; this removes the need to correct for vertical velocity in each temperature profile, thus avoiding the possibility of contaminating the temperatures with measurement noise from the vertical velocity profiles. Further, the low-level cold bias that occurs with the spatially separated transmit and receive antennas of a bistatic RASS system was not significant for the present measurements as the separation between the antennas was minimised. The comparison of RASS and glider temperatures gives confidence in the use of RASS-derived temperatures for investigating the performance of boundary layer models. 相似文献
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D. Engelbart H. Steinhagen U. Görsdorf J. Neisser H. J. Kirtzel G. Peters 《Meteorology and Atmospheric Physics》1999,71(1-2):61-68
Summary At a special measuring site for boundary-layer studies as well as land-surface processes the Meteorological Observatory Lindenberg
of the German Weather Service (DWD) has recently put into operation a newly-desi gned phased-array SODAR/RASS, which has been
developed by METEK on behalf of the DWD. This system provides the vertical profiles of the three-di mensional wind vector
in the boundary layer on an operational basis and is furthermore suitable for getting information on the profile of virtual
temperature up to about 400 m in height based on the addition of RASS components. The following paper describes both the technique
of this SODAR/RASS and the various modes of operation as well as the different options in managing the system. First evaluations
on the data availability concerning the maximum height coverage will give an impression on the system’s capabilities. Finally,
the accuracy of the derived profiles of winds and temperature will be investigated by means of comparisons of the SODAR/RASS
data with measurements of a six-sonde tethered-balloon system as well as meteorological data of a 99 m tower in the vicinity
of the system.
Received November 27, 1998 Revised April 9, 1999 相似文献
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Stefan Emeis Klaus Sch?fer Christoph Münkel Roman Friedl Peter Suppan 《Boundary-Layer Meteorology》2012,143(1):25-35
Since 2006 different remote monitoring methods for determining mixing-layer height have been operated in parallel in Augsburg
(Germany). One method is based on the operation of eye-safe commercial mini-lidar systems (ceilometers). The optical backscatter
intensities recorded with ceilometers provide information about the range-dependent aerosol concentration; gradient minima
within this profile mark the tops of mixed layers. Special software for these ceilometers provides routine retrievals of lower
atmospheric layering. A second method, based on sodar observations, detects the height of a turbulent layer characterized
by high acoustic backscatter intensities due to thermal fluctuations and a high variance of the vertical velocity component.
This information is extended by measurements with a radio-acoustic sounding system (RASS) that directly provides the vertical
temperature profile from the detection of acoustic signal propagation and thus temperature inversions that mark atmospheric
layers. Ceilometer backscatter information is evaluated by comparison with parallel measurements. Data are presented from
2 years of combined ceilometer and RASS measurements at the same site and from comparison with a nearby (60 km) radiosonde
for larger-scale humidity information. This evaluation is designed to ensure mixing-layer height monitoring from ceilometer
data more reliable. 相似文献
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Michael Gerding Christoph Ritter Marion Müller Roland Neuber 《Atmospheric Research》2004,71(4):289-302
Ground-based lidars can provide continuous observations of tropospheric humidity profiles using the Raman scattering of light by water vapour and nitrogen molecules. We will present specific humidity profiles obtained at the high Arctic location Ny-Ålesund (Spitsbergen, 79°N). Under nighttime conditions the observations cover a range from about 500 m altitude up to the upper troposphere. Daylight limits the observations to the lower troposphere, depending on atmospheric transmission and the water vapour content. In a case study on 29 January, simultaneous observations of humidity and aerosol extinction show distinct differences in the various altitudes during the advection of aerosol-rich air masses. In the boundary layer, the aerosol is less affected by the humidity. In the free troposphere, the lidar ratio was observed to be up to 60 sr with some evidence for the uptake of water vapour by the aerosol particles. In another case study from 28 February 2002, the influence of the mean wind direction and the orography on the water vapour concentration near the ground and in the free troposphere will be discussed. During wintertime, a humidity inversion up to about 1.5 km altitude with dry air near the ground has frequently been found with wind from the southeast. Such local effects and small-scale structures observed by stationary lidar mostly cannot be resolved by other sounding methods like passive satellite soundings. 相似文献
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Summary A wind‐profiling Doppler radar equipped with a radio acoustic sounding system (RASS) may be used to estimate the vertical
profile of the vertical flux of heat in the atmosphere. Simultaneous measurements of the time‐varying temperature and vertical
air velocity are combined to give the convective heat flux using the eddy‐correlation method. The accuracy of the estimates
depends on the fundamental accuracy of the temperature and vertical velocity measurements. Also, in common with all eddy‐correlation
methods, uncertainties are introduced by the need to define a suitable averaging time and to remove trends. A problem unique
to RASS is the possible presence of ground and intermittent clutter at close ranges, which can cause errors in the vertical
air velocity measurements. These considerations are discussed with particular reference to observations using a UHF radar
wind profiler situated in an urban environment, where clutter is a serious problem.
A Rank‐Order Signal Processing Algorithm (ROSPA) for recognizing and eliminating outliers in the vertical velocity, is introduced.
It is explained how ROSPA uses both a minimum filter and a median filter on the velocity data. It is shown, using a comparison
with nearly clutter free data from a rural site, that the filtering substantially improves the quality of the noisy urban
data. The paper then compares RASS‐measured urban and rural heat flux profiles, along with the heat flux profile measured
by an instrumented airplane. It is concluded that the main obstacles to RASS heat flux measurements are the effects of winds
and turbulence in the boundary layer, rather than clutter.
Received September 24, 1998 Revised January 27, 1999 相似文献
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利用ARW-WRF模式,以垂直方向40个模式层(对低层加密)、水平方向最高1 km的分辨率,对台风桑美(2006)进行数值模拟,模拟结果与实况基本一致。基于台风桑美(2006)1 km分辨率的模拟结果,对台风低层(海面或地表以上1500 m以下)风场结构进行了分析。结果表明,在台风登陆前,其最大风速半径附近存在水平风速在垂直方向有很强变化的风廓线,该类型风廓线的最大风速高度有明显变化,表现出类似急流的特征;而台风登陆后,其水平风速垂直变化明显减弱,即风廓线类型发生较大变化;另有一种水平风速在高层少变的风廓线类型在台风中是普遍存在的。还根据高层和低层两个切变因子,将台风登陆前的风廓线分为急流型、普通型和过渡型,并进一步分析各类风廓线在台风中出现的位置和急流高度。对急流型风廓线的形成原因也进行了初步探讨,结果表明,超/次梯度风在垂直方向上的变化是形成急流型风廓线的原因,而外围绝对角动量的输送在其中起关键作用。 相似文献
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开展TK-2GPS人影探空火箭探测数据的分析检验,对于了解试验仪器的适用性和数据可靠性及其在人影中的应用前景非常重要。利用TK-2GPS人影探空火箭和L波段探空资料,采用平均偏差、均方根误差和相关系数等分析方法,对两种探空的温度、相对湿度、风向及风速等要素的差异性和变化特征进行了对比分析,并对可能造成差异的原因进行了探讨。结果表明:探空火箭与L波段探空同要素间均呈显著的正相关,通过了0.05及以上显著性检验。温度、风速平均偏差和离散度较小,相关性最好;相对湿度的平均偏差虽大,但相关性较好;风向在各高度层的离散度较大。两种探空的温度、风速垂直廓线变化趋势一致性高;相对湿度垂直廓线变化趋势存在一定差异,前者相对湿度较后者明显偏小。随水平探测距离的增加,探空火箭探测数据相对L波段探空的偏差值有所增大。通过相关分析建立的相对湿度订正方程,能很好地对探空火箭的相对湿度进行订正。 相似文献