CINRAD/SA&SB回波强度定标故障的诊断分析和解决方法

根据CIRAD/SA、SB雷达接收机特点,论述了回波强度定标相关的接收机测试通道、信号主通道以及发射机测试信号流程。根据多年天气雷达技术保障经验,详细论述了回波强度定标故障的诊断分析方法,总结出回波强度定标故障诊断流程,并列举了根据诊断分析方法和诊断流程,排除了由接收机测试通道、信号主通道、发射机射频泄露信号引起的回波强度定标故障的三个典型个例。体现了故障诊断流程在新一代天气雷达技术保障的重要作用,为新一代天气雷达技术保障提供借鉴。     

新一代天气雷达回波异常情况分析

针对新一代天气雷达CINRAD/SA,在运行过程中出现的雷达回波异常情况,从新一代天气雷达受到外界电磁波的干扰、计算机系统、接收机系统、天伺系统等方面,来分析造成雷达回波异常的故障成因,在此基础上,归纳出该型号雷达在使用过程中出现回波异常时,雷达操作、维护人员应掌握的故障排查方法及技巧.     

CINRAD/CC雷达接收机特性曲线异常诊断

依据新一代天气雷达接收机系统工作原理及接收系统特性曲线关键点参数测量方法,结合对CINRAD/CC新一代天气雷达系统特性曲线异常故障的分析,提出了接收系统特性曲线异常故障诊断流程及处理方法,该方法在排除CINRAD/CC新一代天气雷达接收机特性曲线异常的故障实践中得到验证,结果表明:采用这种诊断流程和处理方法不仅快捷、有效,还具有规范性和稳定性,可为雷达技术保障人员处理各种型号新一代天气雷达接收机特性曲线异常故障提供借鉴.     

数字化713天气雷达定标及结果验证

根据气象雷达回波的理论和气象雷达方程，介绍了数字化713天气雷达回波强度定标方法及对定标结果的验证方法。     

CINRAD/SB雷达回波强度定标调校方法

回波强度定标和调校方法是保障CINRAD/SB回波强度测量精度的关键技术,方法不当会导致回波强度测量误差增大,直接影响雷达定量估测降水产品的可靠性。为了满足回波强度测量误差在±1 dBZ范围内的技术要求,根据雷达气象方程,通过对CINRAD/SB接收机测试通道、主通道、天馈系统相关影响回波强度测量误差的因素进行分析,提出了从接收机动态范围和雷达参数调整、线性通道增益定标目标常数定标,到测试通道参数调整的回波强度定标工作流程。总结出以线性通道增益定标目标常数定标为基准,采用测试通道参数测量法或基准法调校,以保证发射功率和接收机动态范围变化导致的回波强度测量误差得到在线实时校正,提高了CINRAD/SB回波强度测量精度。从接收机测试通道、主通道、天馈系统及发射功率4个方面,给出了回波异常的分析和诊断流程。并提出在接收机保护器前端增加机外信号注入口和定标信号功率检测功能,以利于机内外回波强度定标对比校准和消除测试通道参数变化导致回波强度测量误差的建议。     

新一代天气雷达（CINRAD/CD）几种故障分析和排除过程

根据使用CINRAD／CD新一代天气雷达过程中发现的雷达设备硬件和软件故障及维修实践,分析了发射系统人工线故障、雷达系统监控软件在网络正常运行情况下上传监控信息丢失字节、雷达回波同周围雷达相比回波强度存在明显误差及接收系统电源故障等问题的原因,并提出了快速准确的解决方法。     

新一代天气雷达产品故障识别及监测预警系统设计实现

新一代天气雷达故障直接影响数据质量,异常产品的产生对短时临近预报预警带来了重大的影响,实现雷达异常产品实时监测具有一定现实意义。本系统采用WinForm 3层架构+ORM模型架构,通过统计纹理分析、灰度图像特征值分析等图像处理技术实现自动识别雷达异常产品。新一代天气雷达产品故障监测预警系统可以实时、高效、准确检测出异常雷达产品,满足强对流天气预警监测、天气雷达故障预警服务预判、天气雷达产品可用性服务等功能要求,从单部雷达产品数据中识别出异常回波,避免进一步影响多雷达组网拼图,对天气雷达组网产品的质量控制具有重要的意义。     

新一代天气雷达(CINRAD/CD)几种故障分析和排除方法

根据使用CINRAD/CD新一代天气雷达过程中发现的雷达设备硬件和软件故障及维修实践,分析了发射系统人工线故障、雷达系统监控软件在网络正常运行情况下上传监控信息丢失字节、雷达回波同周围雷达相比回波强度存在明显误差及接收系统电源故障等问题的原因,并提出了快速准确的解决方法。     

新一代天气雷达天馈系统故障分析诊断方法和技巧

故障分析诊断技术对保障气象大型装备可靠业务运行具有重要作用。依据CINRAD/SB型新一代天气雷达天馈系统信号流程,通过对新一代天气雷达天馈系统故障诊断方法进行研究,总结出天馈系统漏气、打火故障检测方法,天馈系统损耗大的故障诊断流程和故障定位6种方法。按照故障诊断流程和其中的外接信号源联合频谱仪法,分析诊断、定位并修复了天馈系统天线座内环流器故障导致的雷达观测回波强度偏弱、灵敏度降低故障的典型个例。结果表明,根据雷达现场配备仪表状况,通过故障诊断流程,采用合适方法和技巧,可达到快速定位天馈系统故障部位、在最短时间修复雷达故障目的。     

风廓线雷达回波信号强度定标方法

风廓线雷达返回信号功率定标通常通过返回信号信噪比和系统噪声功率的估算得到。该方法存在着噪声电平的确定、外部噪声等不确定性因素,影响了定标的精度。采用信号源分别对接收机和信号处理器进行定量测试,进而对雷达系统进行定标,是另一种可行的办法,该文利用这种方法对CFL-03风廓线雷达进行了定标,并利用该雷达在东莞2009年7月和8月探测资料与广州S波段天气雷达和地面雨量计资料进行比较。结果表明:用该定标方法得到的回波强度与天气雷达回波强度和地面雨量计资料估算的回波强度基本一致,平均标准差在1 dB左右,表明这种定标方法是可行的。     

新一代天气雷达回波强度自动标校技术

回波强度标定技术直接关系到定量测量的准确度,是新一代天气雷达组网定量测量的基础,是提高天气雷达探测精度的重要手段。简要介绍了新一代天气雷达系统的回波强度自动标校技术,并以CINRAD/CC雷达为例,对新一代多普勒天气雷达(CINRAD/CC)自动标校的技术原理作了详细分析,对其在自动标校中采用的DDS(Direct Digital Synthesis)技术以及标校技术的实施方法作了具体的介绍,对其回波强度自动标校的准确度进行了测量,给出了系统自动标校的实际检验结果。结果表明该系统发射参数、接收参数在出现较大变化时,能保证回波强度的测量准确度在1 dB以内。还对影响自动标校准确度的因素作了分析。     

CINRAD/SC天气雷达系统“太阳法标校”数据修正问题研究

提出CINRAD/SC天气雷达系统的“太阳法标校”数据中含有比较明显的随机误差分量,建议这类数据不宜直接作为调整天线电轴空间指向读数的依据。通过对CINRAD/SC天气雷达系统“太阳法标校”数据生成步骤的分析结果表明：引起“太阳法标校”数据误差的主要因素是“时间错位”。根据这种 “时间错位误差”的产生原理,提出了消除这类误差的方法和步骤,并给出了相应的计算公式。以“时间错位误差”修正后的“太阳法标校”数据作为依据来调整天线电轴指向,将有助于新一代天气雷达系统定向精确度的提高。     

CINRAD／SC天气雷达系统“太阳法标校”数据修正研究

提出CINRAD／SC天气雷达系统的“太阳法标校”数据中合有比较明显的随机误差分量,建议这类数据不宜直接作为调整天线电轴空间指向读数的依据。通过对CINRAD／SC天气雷达系统“太阳法标校”数据生成步骤的分析结果表明：引起“太阳法标校”数据误差的主要因素是“时间错位”。根据这种“时间错位误差”的产生原理,提出了消除这类误差的方法和步骤,并给出了相应的计算公式。以“时间错位误差”修正后的“太阳法标校”数据作为依据来调整天线电轴指向,将有助于新一代天气雷达系统定向精确度的提高。     

基于SYSCAL方法的天气雷达反射率因子在线标定技术

CINRAD天气雷达采用了一种基于SYSCAL的反射率因子在线标定技术,能够在雷达运行中动态检测和校正发射和接收通道的性能变化导致的反射率因子测量偏差,且标定具有良好的性能和时效。通过理论推演详细解析了CINRAD天气雷达反射率因子在线标定的原理,介绍了其在CINRAD/SA天气雷达中的技术实现方式和相应的标定方法及由来。以武汉CINRAD/SA天气雷达的一次在线标定为例对标定实效进行检验和分析,指出了CINRAD天气雷达反射率因子在线标定技术中存在的一些问题。掌握天气雷达反射率因子在线标定原理和技术,对于正确实施标定,保证回波质量和提高雷达故障诊断分析能力,十分必要。     

On the effect of ENSO precipitation anomalies in a global ocean GCM

An ocean general circulation model is used to study the influence of positive precipitation anomalies associated with El Nino and La Nina events. In this idealized model, the precipitation over the appropriate part of the equatorial Indo-Pacific region is doubled for one year. At the surface, salinity anomalies of up to –0.9 parts per thousand result from this anomalous precipitation. Perturbation surface currents ranging from 10–100% of the climatological values are induced in the tropical Indian and Pacific Oceans. A return flow is found beneath the thermocline with upwelling (downwelling) in (outside) the region of enhanced precipitation. The net effect of the precipitation anomalies is to generate a zonal overturning cell which transports fresher surface water away from the forcing region and replaces it with cooler, more saline water from below.     

Individual and combined impacts of ENSO and East Asian winter monsoon on the South China Sea cold tongue intensity

A region of low sea surface temperature (SST) extends southward in the central part of southern South China Sea during boreal winter, which is called the South China Sea cold tongue (SCS CT). The present study investigates the factors of interannual variation of SST in the SCS CT region and explores the individual and combined impacts of El Niño-Southern Oscillation (ENSO) and East Asian winter monsoon (EAWM) on the SCS CT intensity. During years with ENSO alone or with co-existing ENSO and anomalous EAWM, shortwave radiation and ocean horizontal advection play major roles in the interannual variation of the SCS CT intensity. Ocean advection contributes largely to the SST change in the region southeast of Vietnam. In strong CT years with anomalous EAWM alone, surface wind-related latent heat flux has a major role and shortwave radiation is secondary to the EAWM-induced change of the SCS CT intensity, whereas the role of ocean horizontal advection is relatively small. The above differences in the roles of ocean advection and latent heat flux are associated with the distribution of low level wind anomalies. In anomalous CT years with ENSO, low level anomalous cyclone/anticyclone-related wind speed change leads to latent heat flux anomalies with effects opposite to shortwave radiation. In strong CT years with anomalous EAWM alone, surface wind-related latent heat flux anomalies are large as anomalous winds are aligned with climatological winds.

     

新一代天气雷达轴角盒故障的分析处理

CINRAD/SA天气雷达在PPI扫描过程中天线来回摆动,导致雷达无规律出现方位扇形范围无回波,雷达不能正常发挥其有效作用。为查找故障原因,从新一代天气雷达伺服系统信号流程入手,结合雷达基数据分析软件,分析雷达天线运行轨迹,通过信号流程中关键点参数的测量和比较,发现问题出现在轴角编码盒方位环节,导致轴角盒串行方位轴角数据输出不连续,造成雷达无规律出现方位扇形范围无回波。通过对此类故障分析思路与处理经验的总结,对台站级雷达技术保障提供借鉴。     

How do La Niña events disturb the summer monsoon system in Brazil?

The rainy season in most of Brazil is associated with the summer monsoon regime in South America. The quality of this season is important because it rains little during the rest of the year over most of the country. In this study, the influence of La Niña events on the summer monsoon circulation, rainfall and temperature is analyzed with seasonal and monthly resolution, using data from a dense network of stations, giving a comprehensive view of the impact of these events. The expected precipitation percentiles during the monsoon season of La Niña events are calculated, as well as anomalies of surface temperature and thermodynamic parameters. This information is analyzed jointly with anomaly composites of several circulation parameters. The analysis shows that some anomalies, which are consistent and important during part of the season, are smoothed out in a seasonal analysis. There are abrupt changes of anomalies within the summer monsoon season, suggesting the prevalence of regional processes over remote influences during part of the season. In spring there are positive precipitation anomalies in north and central-east Brazil and negative ones in south Brazil. These precipitation anomalies are favored by the perturbation in the Walker and Hadley circulation over the eastern Pacific and South America, and by perturbations in the rotational circulation over southern South America. Northerly moisture inflow from the Atlantic into northern South America is emphasized and diverted towards the mouth of the Amazon by the low-level cyclonic anomaly north of the equator. In December and January, probably triggered by anomalous surface cooling during the spring, there is an anomalous low-level divergence and an anticyclonic anomaly over southeast Brazil. This anomalous circulation directs moisture flux towards south Brazil, causing moisture convergence in part of this region and part of central-west Brazil. The thermodynamic structure in central-east Brazil does not favor precipitation over this region, and the wet anomalies in north Brazil are displaced northward. The dry anomalies in south Brazil almost disappear and even turn positive. In February, after the strongly below normal precipitation of January, the surface temperature anomalies turn positive over southeast Brazil. The low-level anticyclonic anomaly is much weaker than in January. There are positive rainfall anomalies in north Brazil and in the South Atlantic Convergence Zone, and negative ones return to south Brazil.     

2003～2004年强对流灾害性天气多普勒天气雷达产品特征分析

利用银川新一代天气雷达2003～2004年汛期监测到的12次强对流天气过程产品,主要包括：强度、速度、组合反射率、冰雹指数、风廓线、风暴追踪信息、垂直积分液态水含量、中尺度气旋等,特别是径向速度回波产品,根据产品图象特征,将其分为3类,分别从中尺度天气学原理等进行深入的综合分析,得出多普勒天气雷达的几种重要产品对强对流天气特别是冰雹天气的临近预报具有重要使用价值,同时与常规数字化天气雷达进行了对比分析。