双线偏振天气雷达工作的十年总结

本文回顾了我所十年来双线偏振天气雷达工作，系统总结了双线偏振天气雷达在识别云中粒子相态、识别冰雹区、定量测量降雨强度及在水文领域应用等方面的研究成果，以供我国广大天气雷达气象工作者参考。在此基础上，对我们的工作进行了展望。     

TDR——3600HP多普勒气象雷达产品介绍

TDR－3600HP雷达是由美国Kavouras公司生产的速调管全相干多普勒气象雷达，它有丰富的气象产品，这些气象产品有着广泛的应用，它们可以直接用于天气的预警和预报上。它的产品可分为两类：实时产品和二次产品。实时产品是在整个雷达系统中的第三级控制Triton上生成，天气分析人员可通过Triton对雷达进行控制，改变雷达参数并获得实时产品。实时产品又分为两种：一是实时PPI产品，包括求修正的反射率（T），修正过的反射率（Z），多普勒速度（V）及谱宽（W）；二是实时RHI产品，其中也包括以上四种实时产品，使用方便、快速，还可以…     

701—B雷达检修二例

故障一：701－B雷达天控分机仰角只能驱动上升，未能驱动下降；而按驱动下降慢、快档时，指示刻度盘均未动，同时出现过载及电机保险丝BX3－5A或电源保险丝BX1－2A即烧。测角未能正常工作。分析修理：根据故障分析，检查仰角有关电路及有关机械连动部分。（1）仰角运放调零I、II挡检查，驱动上升一切正常；驱动下降各档表针指示有振动不稳归零较慢；电路无开、短路现象，桥式整流以及基准三角波输出、供运放用的正负15伏正常。（2）从CZ2的2－3输出测直流电机电枢（包限位电路元件在内）电阻与正常值60欧姆偏差不大；未加入速度设置驱…     

多普勒雷达观测模式浅谈

根据五家渠多普勒雷达站的工作任务和目的，总结半年来的观测工作经验及有关雷达站的观测模式，结合新疆气候的特征，初步制定了多普勒雷达观测模式，使之能实时地准确地收集、分析雷达回波资料，以利于今后的工作。     

偏振气象雷达发展现状及其应用潜力

偏振雷达是近二十多年来发展起来的新型天气雷达。由于它的问世，极大地促进了雷达气象和云及降水物理学科的发展，增强了人类认识和抗御天气灾害的能力。本文结合中国科学院寒区旱区环境与工程研究所以及世界各国偏振雷达发展的情况和经验，主要就圆偏振雷达、椭圆偏振雷达和双线偏振雷达的发展现状及其在云和降水物理研究以及人工影响天气方面的应用潜力进行说明，它对我国新兴的偏振雷达的发展和应用事业有一定的指导和借鉴意义。     

701雷达三轴一致性调整方法的应用

《高空气象观测手册》关于701雷达观测使用部分规定：机械轴、光轴、电轴一致性的检查每半年进行一次，以保证高空风记录的准确性。雷达的三轴是：光轴一指瞄准镜在正常工作位置时，其物镜中心线中心点所对方向的射线。几何轴（机械轴）一指整个天线阵的各引向天线的对称轴线。它既垂直平整个反射网平面，也垂直干天线仰角转轴。电轴一指天线波瓣交点所对方向的射线，即四个波瓣的等信号强度线。由雷达测角原理中知道：701雷达的测角是由电轴对准目标，而方位、仰角的数值却是天线几何轴所处方位、仰角的数值，所以电轴和几何轴必须一致时，…     

数字化天气雷达和双线偏振雷达的标定方法初探

数字化天气雷达定量探测的精度误差与雷达标定的误差有直接关系。特别是对于双线偏振其差反射率因子ＺＤＲ的典型值又为－３－＋５ｄＢ，而不同类型降水物的ＺＤＲ值可能仅相差十分之几分贝，因此，雷达标定的精度是至关重要的。     

714B雷达的一次故障检修

故障现象：一次雷达总电源开关故障后，回波强度在终端显示下降约30dB。检修分析：此现象最有可能由接收机性能变差和发射机功率下降等原因引起。检修过程：检查发射机，功率指示正常，因而重点怀疑接收机性能变差。而接收机的性能与自频调跟踪的关系极大。经检查发现。自频调并非最佳。通过精心的细调，再调大接收机的增益，终于使得主机显示主要地物——罗浮山的回波强度达到45dB以上（广州714B雷达1990年新装调机时，曾以此作为调校标准），故判定生机正常了。但这时出现了令人困惑的现象，数字终端的显示仍偏弱，且出现彩底。再细看主…     

711雷达发射机故障诊断

发射机是全机核心部分之一，一旦出现故障，雷达便处于瘫痪状态。本文对实际工作中出现的较严重故障；电源电压输出不正常；予调器Ｇ２“热短路”引起Ｒ１１、Ｒ１４烧焦，使无予调脉冲输出；调制管低效及接线板ＪＸ－５软击穿，造成磁控管振荡下降；电缆２ＣＴ５接触不良，导致＋１２５０Ｖ电压偏低等故障，进行全面综合分析。着重介绍故障原因诊断和检修方法，这对维修经验积累是很有益的。     

Wavy Vertical Motions in the ABL Observed by Sodar

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.     

北京燕山地区声回波探测资料的统计分析

近十几年来,许多国家用声雷达长时间的连续观测资料为厂区、城区和山区污染状况的预评价和污染事件的监测和预告服务,并进行了边界层气候和污染气候方面的研究。如何更有效而合理地使用声雷达的长时间连续观测资料,并从中获得有规律性的结果,是十分重要的问题。我们于1984年5月26日至6月23日,10月6日至12月12日,1985年1月8日至2月8日,4月11日至26日四个季节,     

A STATISTICAL ANALYSIS OF SODAR DATA DETECTED IN YANSHAN MOUNTAIN AREA,BEIJING

According to the characteristics of sodar echo,a classified method for temperature stratification is given.By using sodar data observed in Yanshan Mountain area in Beijing,the statistical characteristics for the heightof inversion layer,thermal plume,and the depth of mixed layer are compared.Finally,the appearancefrequency for stable,unstable and neutral stratification is analyzed.     

Sodar Detected Top-Down Convection in a Nocturnal Cloud-Topped Boundary Layer: A Case Study

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 ²_w 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.     

Corrections for Wind-Speed Errors from Sodar and Lidar in Complex Terrain

The quality of lidar and sodar wind estimates is generally judged through comparisons with mast-mounted instruments, and the resulting regressions. Evaluation of the relative merits of lidars versus sodars is complicated by the fact that lidars are generally placed close to a mast whereas sodars are generally placed some distance from a mast so that acoustic reflections off the mast are reduced. This leads to the two technologies, lidar and sodar, not being compared in similar situations. Differences arising from the two geometries can be expected to be larger in complex terrain, where the wind regime can vary significantly spatially. The current work explores these differences in moderately complex terrain. Lidar–mast comparisons are performed with the lidar close to an 80 m mast, and sodar–mast comparisons performed with the sodar 300 m from the mast. Systematic variations in estimated wind speed are found to occur with height, consistent with predictions from a simple flow model. When the lidar was moved to the sodar location, further from the mast, there were significant changes in the estimated wind speeds and a reduction in correlation with the mast-based wind speeds, as expected. However, the correlation between collocated lidar and sodar winds was high. This finding emphasizes that any comparison of two remote sensing instruments needs to be through similar experiments, and that differences in accuracy often reported for the lidar and sodar technologies are likely to be contaminated due to poor comparison configurations. A method was devised to simulate the sodar being collocated with the mast, by using the lidar–sodar measurements and the lidar–mast measurements. It was found that there was then no statistically detectable difference between lidar–mast regressions and sodar–mast regressions for the particular lidar and sodar tested. Both remote sensing instruments were also found to be good estimators of Weibull parameters, as compared with those derived from mast data. The conclusion is that the sodar measured the winds above the sodar with a similar accuracy to the lidar measuring winds above the lidar.     

Foehn signals detected by sodar wind and turbulence measurements in the Rhine Valley, Austria, during the MAP field phase

Summary Within the Mesoscale Alpine Programme MAP conducted in autumn 1999, the vertical structure and the temporal evolution of the planetary boundary layer (PBL) in the Rhine Valley 2km south of Lake Constance were observed with a Remtech PA2 sodar (sound-detection-and-ranging instrument) rendering half-hour averages of the three-dimensional wind profile within the lowest kilometre above ground. During Foehn events, tethered balloon soundings and wind profiler measurements were conducted in addition to the rawinsonde network which was built up for the MAP field campaign.The remote sensing instrument renders a surprisingly high number of valid data during south Foehn. Due to the frequent formation of a cold air pool with stable conditions below the Foehn flow with near-neutral static stability, even more sodar data is valid during Foehn periods than during no Foehn periods. A significant reduction of the sodar data quality is only observed during Foehn events with grounding of the Foehn at the sodar site due to high background noise. At higher levels, a Foehn signal can be detected from the sodar wind and turbulence intensitiy information. With Foehn, higher wind speeds and larger turbulence intensities occur than without Foehn. Comparisons to rawinsonde and tethersonde soundings and wind profiler measurements at sites nearby reveal the spatial inhomogeneity of the Foehn flow within this part of the valley as well as instrumental short-comings. Different methods to determine the mixing height using the vertical sounding devices lead to some uncertainty of mixing height estimates which however can reasonably be explained.     

Characteristics of wind speed and wind direction in the atmospheric boundary layer on the southern coast of Bulgaria

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.     

Use of a High-Resolution Sodar to Study Surface-layer Turbulence at Night

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.     

Hilltop Wind Profiles Using Sodar

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.     

Mixing-height estimation in the convective boundary layer using sodar data

Sodar has been used for about 20 years to determine mixing height. However, estimation of the height of a convective boundary layer (CBL) that exceeds the sodar-probing range is still an unsolved question. As one possible way, it is suggested that one adapt a simple mixed-layer model to sodar observations during the morning growth period of the CBL, when its top can be clearly detected. Results are compared with other methods for CBL-height estimation from sodar data that have been proposed in the literature. Finally, some prognostic aspects are discussed.