Retrieving microphysical properties and air motion of cirrus clouds based on the doppler moments method using cloud radar

Radar parameters including radar reflectivity,Doppler velocity,and Doppler spectrum width were obtained from Doppler spectrum moments.The Doppler spectrum moment is the convolution of both the particle spectrum and the mean air vertical motion.Unlike strong precipitation,the motion of particles in cirrus clouds is quite close to the air motion around them.In this study,a method of Doppler moments was developed and used to retrieve cirrus cloud microphysical properties such as the mean air vertical velocity,mass-weighted diameter,effective particle size,and ice content.Ice content values were retrieved using both the Doppler spectrum method and classic Z-IWC(radar reflectivity-ice water content) relationships;however,the former is a more reasonable method.     

Comparison of Precipitation Observations from a Prototype Space-based Cloud Radar and Ground-based Radars

A prototype space-based cloud radar has been developed and was installed on an airplane to observe a precipitation system over Tianjin,China in July 2010.Ground-based S-band and Ka-band radars were used to examine the observational capability of the prototype.A cross-comparison algorithm between different wavelengths,spatial resolutions and platform radars is presented.The reflectivity biases,correlation coefficients and standard deviations between the radars are analyzed.The equivalent reflectivity bias between the S-and Ka-band radars were simulated with a given raindrop size distribution.The results indicated that reflectivity bias between the S-and Ka-band radars due to scattering properties was less than 5 dB,and for weak precipitation the bias was negligible.The prototype space-based cloud radar was able to measure a reasonable vertical profile of reflectivity,but the reflectivity below an altitude of 1.5 km above ground level was obscured by ground clutter.The measured reflectivity by the prototype space-based cloud radar was approximately 10.9 dB stronger than that by the S-band Doppler radar(SA radar),and 13.7 dB stronger than that by the ground-based cloud radar.The reflectivity measured by the SA radar was 0.4 dB stronger than that by the ground-based cloud radar.This study could provide a method for the quantitative examination of the observation ability for space-based radars.     

一次东北冷涡云降水垂直结构特征分析

利用辽宁阜新国家站(121.7458°E,42.0672°N)的毫米波云雷达(8 mm)和微雨雷达(12.5 mm)对2020年8月12-13日东北冷涡影响下的一次降水过程进行了观测,分析了云降水的垂直结构特征并探讨了降水机制。结果表明：本次过程中,云水平方向发展不均匀,以层状云和层积混合云为主,云内有时还嵌有对流泡。云降水阶段性变化明显,先后出现了层状云降水、层积混合云降水和对流云降水。层状云降水和层积混合云降水均表现出明显的亮带特征,但层积混合云降水的雷达回波强度、回波顶高和降水强度明显大于层状云降水。对流云降水的雷达回波会因强降水而产生明显衰减,因此回波顶高不能表示出实际的云顶情况。层状云降水阶段,云雷达反射率随高度降低增长缓慢,雨滴在下落过程中受蒸发和碰并的共同作用,反射率降低。与层状云降水相比,层积混合云降水的碰并效应强,且由于前期降水对近地面的增湿作用,使云下蒸发弱。对流云降水阶段,反射率的增长主要发生在冰水混合层,有利于大滴的产生,拓宽了云滴谱,提高了碰并效率。     

94GHz云雷达回波及测云能力分析

重点利用英国的94 GHz Galileo测云雷达,结合35 GHz云雷达、地面雨滴谱仪、雨量计和探空资料等,分析了94 GHz 雷达的回波特征及测云能力。结果表明：（1）94 GHz云雷达能清楚反映出云及弱降水过程的云系结构变化和云内小尺度变化,可以探测到雾,雾的多普勒速度杂乱;（2）94 GHz云雷达区别于厘米波雷达的较显著的回波特征是层状云降水的0℃层亮带下面雷达反射率因子降低不明显或没有降低及0℃层亮带上面存在0℃层暗带,分别是因为雨滴较大及冰晶较大产生非瑞利散射引起的,暗带区域的宽度一般在600 m以下,暗带区域的许多冰晶聚合物最大尺度可超过3 mm,有些暗带区域的许多冰晶聚合物最大尺度可超过6.8 mm,多普勒速度及谱宽显著增大的地方是融化层顶;（3）与35 GHz测云雷达相比,由于衰减和非瑞利散射,降水时的94 GHz雷达反射率因子远小于35 GHz雷达反射率因子,使探测到的高云云顶高度偏低,但94 GHz云雷达抑制地物杂波的能力更高,在晴空低云探测方面具有优势。这些结果为中国正在研制的94 GHz云雷达回波可靠性分析提供了参考。94 GHz云雷达与其他探测手段结合,可揭示各种天气形成的物理机制,对天气预报、云物理的发展、人工影响天气、气候变化的研究均有重要意义。     

The First Observed Cloud Echoes and Microphysical Parameter Retrievals by China's 94-GHz Cloud Radar

By using the cloud echoes first successfully observed by China's indigenous 94-GHz SKY cloud radar, the macrostructure and microphysical properties of drizzling stratocumulus clouds in Anhui Province on 8 June2013 are analyzed, and the detection capability of this cloud radar is discussed. The results are as follows.(1) The cloud radar is able to observe the time-varying macroscopic and microphysical parameters of clouds,and it can reveal the microscopic structure and small-scale changes of clouds.(2) The velocity spectral width of cloud droplets is small, but the spectral width of the cloud containing both cloud droplets and drizzle is large. When the spectral width is more than 0.4 m s-1, the radar reflectivity factor is larger(over –10 dBZ).(3) The radar's sensitivity is comparatively higher because the minimum radar reflectivity factor is about–35 dBZ in this experiment, which exceeds the threshold for detecting the linear depolarized ratio(LDR) of stratocumulus(commonly –11 to –14 dBZ; decreases with increasing turbulence).(4) After distinguishing of cloud droplets from drizzle, cloud liquid water content and particle effective radius are retrieved. The liquid water content of drizzle is lower than that of cloud droplets at the same radar reflectivity factor.     

基于多源资料的积层混合云降水微物理特征

基于地基云雷达、微雨雷达和天气雷达等遥测设备观测资料,结合挂载KPR云雷达和DMT粒子测量系统的飞机平台,详细分析了山东积层混合云降水过程的云降水微物理结构特征。结果表明,积层混合云降水过程呈现层状云和对流云降水特征。零度层以上,5～6 km高度层内,对流云降水多普勒速度和谱宽均大于层状云,说明对流云降水环境垂直气流、粒子尺度等均大于层状云。对流云降水,云雷达和微雨雷达时空剖面上出现由衰减造成的“V”字形缺口,云雷达衰减程度大于微雨雷达,且随高度增加,衰减越大。层状云降水,零度层亮带附近,雷达反射率因子跃增高度比多普勒速度高80 m,多普勒速度跃增高度又比谱宽高20 m。降水云系零度层附近降水机制复杂,粒子形态有辐枝冰晶聚合物、针状冰晶聚合物和云滴;0°C层以上,5～6 km处,对流云降水的多普勒速度和谱宽均大于层状云降水,即对流云降水环境垂直气流、粒子尺度范围等均大于层状云降水。     

SACOL站冰云粒子下降末速度的反演及其时空分布特征研究

冰云是影响气候变化最为重要的因子之一,其生命周期的变化在很大程度上决定了冰云的气候辐射效应。冰云粒子下降末速度是影响冰云生命周期的关键参数。为了开展对冰云粒子下降末速度的研究,利用兰州大学半干旱气候与环境监测站Ka波段毫米波云雷达2013年8月至2015年7月连续观测数据,反演了冰云粒子的下降末速度（V_t）,并根据雷达反射率因子（Z）与V_t的关系计算了拟合因子a、b的值;在此基础上应用聚类分析方法,对比分析了4种不同特性冰云Z、V_t和拟合因子a、b的时、空分布特征,进而尝试通过参数垂直分布特征识别研究云中不同位置上云微物理过程的变化。结果表明:冰云粒子下降末速度的分布与雷达反射率因子有很好的对应,最大频率都出现在距离地面约7 km高度处,且具有显著的季节变化,粒子下降末速度在暖季较冷季可增大25%,峰值出现在6月和9月;云层较厚且持续时间长的第一、三类冰云,其雷达反射率因子、粒子下降末速度及拟合因子a和b的平均值都显著大于云层较薄且持续时间短的第二、四类云。垂直方向上,Z、V_t和拟合因子b从云顶到云底随着高度的降低呈现先增大后减小的趋势,体现了云粒子在云顶区域成核和水汽凝华效应,随着粒子在下落过程中碰并增长,云滴粒子逐渐增大,水汽的凝华和粒子的聚合起主要作用,最后在云底部分,云粒子蒸发、升华减小消亡的过程。由此表明中纬度干旱半干旱地区冰云是从云顶到云底自上而下的形成过程。      

福建省古田试验区云系回波特征与人工增雨作业条件分析

利用2008—2012年4—6月古田试验区的新一代天气雷达、探空及地面雨量观测等资料,结合天气形势分析,研究古田试验区云系的回波特征与人工增雨作业条件,结果表明:影响古田试验区的主要天气系统分别为低涡切变、暖区辐合、高空槽和大陆高压。降水云系以积层混合云为主,其次为积状云。天气系统所对应的云系回波类型及降水情况有明显差异,积层混合云的结构有利降水;积层混合云大于25 d Bz的回波面积明显比积状云大,且平均回波顶高和最大回波顶高均比积状云低;积状云的垂直积分液态水含量明显比积层混合云大;积状云和积层混合云的负温层厚度超2 km;积层混合云的最大回波强度、大于25 d Bz的回波面积和负温层厚度与区域平均日雨量有着明显的对应关系。古田试验区积层混合云的作业指标为回波强度大于25 d Bz,大于25d Bz的回波面积S25 d Bz要大于400 km~2,回波顶高大于5.5 km,负温层厚度大于1.5km,垂直积分液态水含量大于1 kg/m~2。     

毫米波云雷达功率谱密度数据的检验和 在弱降水滴谱反演中的应用研究

本文首先利用数值模拟的方法,分析了利用毫米波云雷达功率谱密度反演雨滴谱时,降水粒子米散射效应、空气湍流、空气上升速度等对雨滴谱和液态水含量等参数反演的影响;建立了功率谱密度处理及其直接反演雨滴谱、液态水含量、降水强度和空气上升速度的方法;并利用2012年7月在云南腾冲观测的二次弱降水数据,采用毫米波雷达和Ku波段微降水雷达观测的回波强度、径向速度垂直廓线以及780 m高度上的功率谱密度对比的方法,以及毫米波云雷达观测的780 m高度上功率谱密度、回波强度与地面雨滴谱计算得到的这些量的对比方法,分析了毫米波雷达数据的可靠性;并将780 m高度上毫米波雷达反演的雨滴谱与地面雨滴谱数据进行了对比,分析了毫米波雷达反演的雨滴谱的准确性;分析了毫米波雷达回波强度偏弱的原因,讨论了该高度以下降水对毫米波雷达衰减的影响。结果表明:空气湍流对弱降水微物理参数反演影响不大,而空气上升速度和米散射效应均对反演结果有一定影响;毫米波雷达观测到的径向速度和功率谱密度与微降水雷达比较一致,回波强度的垂直廓线的形状与微降水雷达也比较一致,但毫米波雷达观测的回波强度偏弱;与雨滴谱计算值相比,毫米波雷达观测的低层的回波强度也偏弱,天线上的积水是造成毫米波雷达回波强度变弱的主要原因。毫米波雷达观测的低层的功率谱密度与地面雨滴谱观测的数据形状比较一致,但有一定的位移。毫米波雷达反演的雨滴谱与地面观测的谱型和粒子大小也比较一致。这些结果初步验证了毫米波雷达观测的功率谱密度及其反演方法的可靠性。     

深圳S波段与X波段双偏振雷达在定量降水估计中的应用

双偏振多普勒天气雷达的一个重要应用是进行定量降水估计（QPE）,它可以获得反射率（Z_H）、差分反射率（Z_DR）和差传播相移率（K_dp）这些与降水粒子有关的信息,常用的双偏振雷达降水估计方法有基于Z_H的R（Z_H）、基于Z_H和Z_DR的R（Z_H,Z_DR）、基于K_dp的R（K_dp）和基于K_dp与Z_DR的R（K_dp,Z_DR）这4种。文中利用深圳市S波段和X波段双偏振多普勒雷达探测资料,结合高精度地形数据和雨滴谱仪观测数据,设计了基于双偏振量的定量降水估计方法:首先利用地形数据和雷达地理信息,分析了雷达的遮挡状况,形成了这两部雷达的复合平面扫描仰角信息;随后利用雨滴谱仪观测资料,使用T矩阵方法统计得到了深圳地区的上述4种降水反演方法的参数;最后设计了混合降水反演方法,基于双偏振信号（即K_dp和Z_DR）的强弱,使用不同的降水反演方法进行定量降水估计。基于12个降水个例,利用各反演方法产生的定量降水估计结果与雨量计观测资料比较。结果表明,混合降水反演方法在降水反演的准确度和稳定性上均优于任何一种单一定量降水估计反演方法。基于文中介绍的定量降水估计方法,使用深圳S波段和X波段雷达产生了定量降水估计产品,并与深圳目前业务定量降水估计产品进行对比评估。结果表明,使用本方法产生的定量降水估计产品在准确度和稳定性上要优于目前的业务产品。此外,X波段雷达的定量降水估计产品性能要略高于S波段雷达的定量降水估计产品,这说明高时、空分辨率的X波段雷达可以提高定量降水估计精度。但由于雷达扫描平面内双偏振雷达对融化层和冰区的偏振量观测与降水的关系尚未明确,因此,本方法仅适用于雷达扫描平面内液态降水区。      

Application of a Three-dimensional Variational Method for Radar Reflectivity Data Correction in a Mudslide-inducing Rainstorm Simulation

Various types of radars with different horizontal and vertical detection ranges are deployed in China, particularly over complex terrain where radar blind zones are common. In this study, a new variational method is developed to correct threedimensional radar reflectivity data based on hourly ground precipitation observations. The aim of this method is to improve the quality of observations of various types of radar and effectively assimilate operational Doppler radar observations. A mudslide-inducing local rainstorm is simulated by the WRF model with assimilation of radar reflectivity and radial velocity data using LAPS(Local Analysis and Prediction System). Experiments with different radar data assimilated by LAPS are performed. It is found that when radar reflectivity data are corrected using this variational method and assimilated by LAPS,the atmospheric conditions and cloud physics processes are reasonably described. The temporal evolution of radar reflectivity corrected by the variational method corresponds well to observed rainfall. It can better describe the cloud water distribution over the rainfall area and improve the cloud water analysis results over the central rainfall region. The LAPS cloud analysis system can update cloud microphysical variables and represent the hydrometeors associated with strong convective activities over the rainfall area well. Model performance is improved and the simulation of the dynamical processes and moisture transport is more consistent with observation.     

Observational Characteristics of Cloud Vertical Profiles over the Continent of East Asia from the CloudSat Data

The CloudSat satellite data from June 2006 to April 2011 are used to investigate the characteristics of cloud vertical profiles over East Asia(20°-50°N,80°-120°E),with particular emphasis on the profiles of precipitative clouds in comparison with those of nonprecipitative clouds,as well as the seasonal variations of these profiles.There are some obvious differences between the precipitative and nonprecipitative cloud profiles.Generally,precipitative clouds mainly locate below 8 km with radar reflectivity in the range of-20 to 15 dBZ and maximum values appearing within 2-4-km height,and the clouds usually reach the ground;while nonprecipitative clouds locate in the layers of 4-12 km with radar reflectivity between-28 and 0 dBZ and maximum values within 8-10-km height.There are also some differences among the liquid precipitative,solid precipitative,and possible drizzle precipitative cloud profiles.In precipitative clouds,radar reflectivity increases rapidly from 11 to 7 km in vertical,implying that condensation and collision-coalescence processes play a crucial role in the formation of large-size drops.The frequency distribution of temperature at-15℃ is consistent with the highest frequency of radar reflectivity in solid precipitative clouds,which suggests that the temperatures near-15℃ are conductive to deposition and accretion processes.The vertical profiles of liquid precipitative clouds show almost the same distributions in spring,summer,and autumn but with differences in winter at mainly lower levels.In contrast,the vertical profiles of solid precipitative clouds change from spring to winter with an alternate double and single high-frequency core,which is consistent with variations of the frequency distribution of temperature at-15℃.The vertical profiles of nonprecipitative clouds show a little change with season.The observations also show that the precipitation events over East Asia are mostly related to deep convective clouds and nimbostratus clouds.These results are expected to be useful for evaluation of weather and climate models and for improvement of microphysical parameterizations in numerical models.     

华北地区一次积层混合云降水的数值模拟研究

利用WRF ARW中尺度数值模式对2009年4月18日华北地区的一次积层混合云系降水进行模拟。首先,对实况的天气形势和雷达反射率及垂直剖面进行分析;并通过垂直剖面对其流场结构概念图进行分析;然后,通过对比,模拟的自然降水分布与实测结果基本一致,模拟的雷达组合反射率和雷达反射率的垂直剖面与实测结果也基本一致;通过分析云中各要素的分布,了解了积层混合云系的微物理特征和动力特征;最后对积层混合云降水机制进行探讨。结果表明：积层混合云水凝物含水量分布不均匀,对流云和层状云相互粘连跨接,水平方向充分混合,雨水的大值中心、云水的大值中心及冰晶的大值区相互对应,存在播撒-供给机制。从动力场来看,在低层对流云区域垂直上升速度较大,高层对流云区域的旁侧有较明显的下沉气流,云区低层存在辐合,高层存在辐散,此种配置有利于维持云系的发展。积层混合云不仅在层状云区有层状云的简单的＂播撒-供给＂机制,或在积状云区有粒子群的循环增长机制,而且可以发生层云—积云间的粒子群交换。     

C波段调频连续波天气雷达探测系统及观测试验

对降水云更高时、空分辨率观测资料的需求推动了天气雷达技术的发展,调频连续波雷达(FMCW)系统采用收发分置双天线体制,采用数字直接移相(DDS)技术和快速傅里叶变换(FFT)信号处理技术,获取高度分辨率达到15、30 m,探测周期2—3 s的回波功率谱分布和谱参数,具有脉冲多普勒雷达无法比拟的探测优势。C波段FMCW(C-FMCW)雷达最小可测信号功率达到-170 dBm,微弱信号的定量标校是技术难点。采用标准信号源输出单频信号,经过数字直接移相扩展为与雷达系统相同扫频范围信号,得到最小输入功率可达-169.77 dBm的定标曲线,由定量标校后的谱分布计算得到回波强度谱密度分布。该雷达于2013年6月起在安徽定远开始观测,利用8月24日降水过程探测数据,与距离该地48 km的蚌埠和83 km的合肥SA扫描雷达观测数据,分别进行对流云与层状云的观测比对分析。对于均匀分布的层状降水云,C-FMCW雷达与SA雷达探测结果基本接近, C-FMCW雷达与蚌埠SA雷达的平均均方根误差为1.75 dB,与合肥SA雷达的平均均方根误差为2.02 dB,C-FMCW雷达与两部SA雷达探测的回波强度差异小于1 dB。对观测试验谱参数及回波强度谱密度分布进行了初步分析,C-FMCW雷达在研究降水云体的相态分区、晴空大气边界层回波等方面有较好的应用前景,有助于加深对强降水云中垂直运动的强烈变化的探测和认识。     

Reliability of X-band Dual-polarization Phased Array Radars Through Comparison with an S-band Dual-polarization Doppler Radar

Based on the observations of a squall line on 11 May 2020 and stratiform precipitation on 6 June 2020 from two X-band dual-polarization phased array weather radars (DP-PAWRs) and an S-band dual-polarization Doppler weather radar (CINRAD/SA-D), the data reliability of DP-PAWR and its ability to detect the fine structures of mesoscale weather systems were assessed. After location matching, the observations of DP-PAWR and CINRAD / SA-D were compared in terms of reflectivity (ZH), radial velocity (V), differential reflectivity (ZDR), and specific differential phase (KDP). The results showed that: (1) DP-PAWR has better ability to detect mesoscale weather systems than CINRAD/SA-D; the multi-elevation-angles scanning of the RHI mode enables DP-PAWR to obtain a wider detection range in the vertical direction. (2) DP-PAWR’s ZH and V structures are acceptable, while its sensitivity is worse than that of CINRAD/SA-D. The ZH suffers from attenuation and the ZH area distribution is distorted around strong rainfall regions. (3) DP-PAWR’s ZDR is close to a normal distribution but slightly smaller than that of CINRAD/SA-D. The KDP products of DP-PAWR have much higher sensitivity, showing a better indication of precipitation. (4) DP-PAWR is capable of revealing a detailed and complete structure of the evolution of the whole storm and the characteristics of particle phase variations during the process of triggering and enhancement of a small cell in the front of a squall line, as well as the merging of the cell with the squall line, which cannot be observed by CINRAD/SA-D. With its fast volume scan feature and dual-polarization detection capability, DP-PAWR shows great potential in further understanding the development and evolution mechanisms of meso-γ-scale and microscale weather systems.     

双线偏振多普勒雷达资料质量分析

以中国气象科学研究院灾害天气国家重点实验室的车载C波段双线偏振多普勒雷达（CPDRW）2011年完成升级改造后观测的一次大范围层状云降水过程资料为例,讨论了该设备改造后探测资料质量的改进情况及其对降水粒子的探测性能,同时利用模糊逻辑法结合地物的常规特性和偏振特性,建立了一种运用双线偏振雷达观测资料识别地物及地物与降水混合回波的方法,并利用该雷达的观测资料对识别结果进行了分析检验,最后统计分析了降水回波的差分反射率因子(Z_DR)、零滞后互相关系数(ρ_HV（0）)与信噪比的关系,以及系统初始相位的稳定性及降水资料的一致性。分析结果表明,在常规参量的基础上添加偏振参量并采用模糊逻辑法构建的综合识别模式和常规识别模式都能较好地识别地物,但综合识别模式明显改善了常规识别模式0速度区过度识别的问题,且在地物与降水回波混合的情况下叠加混合回波识别模式具有更加明显的优势。雷达改造前,Z_DR及ρ_HV（0）在信噪比小于25 dB时受噪声影响很大,测量值存在较大误差,资料变得不可信;通过这次的升级改造,其信噪比探测阈值由25 dB降低到15 dB。系统初始相位比改造前更加稳定,随仰角和时间的波动性更小。利用垂直扫描数据进行系统误差订正后的Z_DR资料能较好地反映降水粒子的实际情况,Z_DR随信噪比的变化较之改造前更加平稳,而对差传播相移Φ_DP进行分类处理后拟合的差传播相移率K_DP资料也与实际情况一致。     

对非球形冰晶94 GHz云雷达后向散射和衰减的研究

针对94 GHz毫米波云雷达的数据处理,基于离散偶极子近似法(DDA)计算了几种非球形冰晶的后向散射及衰减效率,探讨了不同冰云模型下冰云的雷达反射率因子(Z_e)和衰减系数(k)及冰水含量(IWC,记作W)的关系。结果表明:(1)形状对冰晶的散射及衰减效率与粒子大小有关。(2)在实际的冰云中,将六角形冰晶和椭圆冰晶看做同体积的球形粒子将低估其衰减和后向散射。将聚合物冰晶看做等体积球形,将高估其后向散射及衰减,子弹花冰晶的后向散射与同体积的球形相比有减小也有增大,但是衰减比同体积球形的小。(3)冰云模型对Z_e-k、Z_e-W关系具有较大影响,假设滴谱相同的条件下,得到了具体冰云模型下对应Z_e-k、Z_e-W关系的系数。这些探讨为我国W波段云雷达的数据处理提供了参考。     

The operational weather radar of Fossalon di Grado (Gorizia, Italy): accuracy of reflectivity and differential reflectivity measurements

Summary The error structure of radar measurements should be accurately known in order to provide reliable estimates for a number of quantitative meteorological applications, from rainfall rate estimation to cloud microphysics. The aim of this paper is to give a detailed characterization of Z _H and Z _DR measurements obtained by the weather radar of Fossalon di Grado (Gorizia, Italy). Vertical-looking observations are used to determine the system bias on differential reflectivity and to estimate the measurement error on both Z _H and Z _DR in the rain medium. It is estimated that no bias is affecting Z _DR and the accuracy of Z _H and Z _DR is 0.8 and 0.1 dB, respectively. A similar evaluation is done in the rain medium at larger ranges with the antenna pointing at low elevation angles. The long time stability of the absolute reflectivity calibration is also established by radar-rain gage inter-comparison over almost 200 hours of precipitation data collected during nearly two years. Received June 21, 2001 Revised November 13, 2001     

C-FMCW雷达对江淮降水云零度层亮带探测研究

不同于体扫雷达探测降水系统,垂直指向雷达可探测降水云中粒子垂直演变的微物理过程。C波段调频连续波垂直指向雷达 (C-FMCW) 采用收发分置天线,数据垂直分辨率达15~30 m,时间分辨率达2~3 s,利用其2013年6—8月在安徽定远探测数据对降水云垂直结构特征及亮带中融化微物理过程进行研究。6次降水过程共计46 h中的39.1%数据具有清晰的亮带结构特征,期间降水占地面总降水量的15%;江淮雨季层状云、对流云和混合性降水系统中均出现零度层亮带,层状云中亮带长时间维持,对流降水系统移出后减弱阶段的亮带结构稳定,混合降水系统中的对流扰动加强冲破了亮带结构。以融化层中最大回波强度Z_p所在高度进行融化层的粒子碰并增长和破碎减弱分层分析,上半层融化过程主要表现为碰并增长,下半层则是粒子破碎减弱。剔除了介电常数、下降速度引起的粒子浓度改变影响后,层状云和对流降水后期的回波强度加强表明融化增长程度接近,后者略强,混合降水云的融化增长最强。     

A Test Pattern Identification Algorithm and Its Application to CINRAD/SA(B) Data简

A variety of faulty radar echoes may cause serious problems with radar data applications,especially radar data assimilation and quantitative precipitation estimates.In this study,＂test pattern＂ caused by test signal or radar hardware failures in CINRAD （China New Generation Weather Radar） SA and SB radar operational observations are investigated.In order to distinguish the test pattern from other types of radar echoes,such as precipitation,clear air and other non-meteorological echoes,five feature parameters including the effective reflectivity data percentage （Rz）,velocity RF （range folding） data percentage （RRF）,missing velocity data percentage （RM）,averaged along-azimuth reflectivity fluctuation （RNr,z） and averaged along-beam reflectivity fluctuation （RNa,z） are proposed.Based on the fuzzy logic method,a test pattern identification algorithm is developed,and the statistical results from all the different kinds of radar echoes indicate the performance of the algorithm.Analysis of two typical cases with heavy precipitation echoes located inside the test pattern are performed.The statistical results show that the test pattern identification algorithm performs well,since the test pattern is recognized in most cases.Besides,the algorithm can effectively remove the test pattern signal and retain strong precipitation echoes in heavy rainfall events.