共查询到19条相似文献，搜索用时 109 毫秒
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利用地面观测资料参考标定雷达VAD资料气压高度方法研究 总被引：1，自引：1，他引：0
针对雷达VAD资料因不包含气压高度信息而在使用中受到限制的问题,设计了VAD资料气压高度标定方案。提出了以雷达站所在地地面气象观测要素作为参考的标定方法。具体为在压高公式中引人多元大气温度递减方案,地面基础要素由雷达站配备的地面自动气象观测站提供。针对这个方案敏感的温度垂直递减率,利用2007年全年探空资料计算得到温度垂直递减率随高度、时间、区域变化的分布,并分别进行常数温度递减率、随高度变化、随时间变化的温度垂直递减率,以及随两者同时变化的温度垂直递减率对标定结果误差影响的敏感性分析,并与传统的气候标定方案误差进行对比。通过一年的实际观测资料试验,结果表明：相对于不引入观测的气候统计值标定方案,可大大缩减标定误差。尤其是随高度和时间同时调整的温度垂直递减率的地面观测要素参考标定方案的误差最小,适应VAD资料的特点。 相似文献
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为了寻求适合珠海-澳门双偏振雷达的差分反射率标定方法,提升其探测的准确性和稳定性,对珠澳雷达的太阳法和垂直指向法的标定结果进行了分析对比。对比表明两个标定方法确定的系统偏差之间存在较大的差异。为了确定真实的系统偏差,基于业务运行的体积扫描数据,在初始差分相移订正的基础上,用差分相移、反射率、信噪比和相关系数作为筛选条件,筛选了适合作为标定参照物的小雨和干雪,对珠澳雷达的标定结果进行了验证并分析了标定误差的成因。结果表明以小雨和干雪作为目标物得到的差分反射率系统偏差和太阳扫描法得到的结果非常一致,且在超过两个月时间内表现较为稳定,可以用于对雷达系统的差分反射率偏差进行长期的在线监控。垂直指向法标定的结果存在明显偏差。与英国Thurnham C波段雷达以及南京大学C波段雷达的垂直入射标定数据的横向对比和分析表明,珠澳雷达的垂直指向法标定受到位于天线罩顶部的航空障碍灯和维护窗的影响,使得标定结果出现偏差。 相似文献
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初步探索了CE318型太阳光度计的室内和野外标定方法, 并对两种方法的标定结果进行对比。基于积分球辐射源的辐亮度标定方法, 对CE318型太阳光度计不同波段天空散射辐射通道进行标定实验; 分别采用Langley标定法和标准仪器相对标定方法, 对CE318型太阳光度计的不同波段太阳直接辐射通道进行了标定实验。实验结果显示:天空散射辐射通道的标定结果在670 nm, 870 nm和1020 nm波段与仪器出厂时给定的标定结果偏差不超过6%, 而440 nm波段处得到的标定结果要高于出厂时给定的结果, 偏离幅度约18.9%。太阳直接辐射各通道的标定结果普遍大于出厂时给定的结果, 说明滤光片老化较为严重, 需要进行更换, 以保证观测精度。由于标准仪器相对标定方法对太阳直接辐射通道的标定结果明显优于Langley法, 因此利用标准仪器相对标定方法对中国气象局太阳光度计站网仪器进行定期标定更能够保证仪器观测数据的准确性。 相似文献
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《气象科技》2019,(1)
为了寻求适合珠海-澳门双偏振雷达的差分反射率标定方法,提升其探测的准确性和稳定性,对珠澳雷达的太阳法和垂直指向法的标定结果进行了分析对比。对比表明两个标定方法确定的系统偏差之间存在较大的差异。为了确定真实的系统偏差,基于业务运行的体积扫描数据,在初始差分相移订正的基础上,用差分相移、反射率、信噪比和相关系数作为筛选条件,筛选了适合作为标定参照物的小雨和干雪,对珠澳雷达的标定结果进行了验证并分析了标定误差的成因。结果表明以小雨和干雪作为目标物得到的差分反射率系统偏差和太阳扫描法得到的结果非常一致,且在超过两个月时间内表现较为稳定,可以用于对雷达系统的差分反射率偏差进行长期的在线监控。垂直指向法标定的结果存在明显偏差。与英国Thurnham C波段雷达以及南京大学C波段雷达的垂直入射标定数据的横向对比和分析表明,珠澳雷达的垂直指向法标定受到位于天线罩顶部的航空障碍灯和维护窗的影响,使得标定结果出现偏差。 相似文献
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沈焕琦 《沙漠与绿洲气象(新疆气象)》1994,(3)
1标定和维护1．1天线标定：标定水平时在第一次标定以后（天线没大修，没加漆以前）将水准仪的放置位置，旋钮位置做好记号并记录，以后的月标定就可简单的多，只要略调天线的三个螺钉就行了。方位标定在第一次标定好以后，记下固定目标物回波的仰角、距离、方位，以后就以此固定回波标准标定天线不需再用经纬仪。1．2天线上滑环易服。金属表面的油污、积灰和氧化物，很易产生各种各样奇特多处故障现象。所以，集流环接触点一定要定期维护，维护后还应“擦上一层薄润滑油”，滑环维护后，若层间绝缘电阻仍太小，可松动集流环上面的小螺丝，… 相似文献
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雷达接收机对数动态特性的标定是运用信号源输出信号对雷达接收机、数字视频积分器（ＤＶＩＰ）进行定标，以标定的雷达接收机、ＤＶＩＰ输出特性来对回波信号功率进行测量。１ 标定过程 海口和三亚７１３雷达用的是新型数字化终端，标定步骤如下：２ 实际操作过程２．１ 信号处理（ＳＰ）的主要测试内容、方法、步骤 信号处理板简图：２．１．１ 检查１．５Ｖ基准电压 该电压由电压基准蕊片ＬＭ３３６产生２．５Ｖ，分压后得到 １．５Ｖ送往 Ａ／Ｄ 蕊片ＡＤＳ８０４Ｕ作为Ａ／Ｄ转换的基准电压。 方法：用万用表在信号处理器板的ＶＲＥＦ… 相似文献
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利用地物杂波进行天气雷达强度标定 总被引：1，自引：0，他引：1
地物杂波的回波强度相对稳定,对成都和新疆地区的寺物杂波强度的统计表明,地物杂波的雷达反射因子方差分别小于３ｂｄ和１．５ｂｄ,因此,地物回波可作为一个标准目标,用来对天气雷达进行强度的标定,本文给出了这种强度标定的流程图,标定方法和标定结果。使用这种标定方法将大大改善天气雷达的维护和使用质量。 相似文献
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Covadonga Palencia Claude Berthet Marta Massot Amaya Castro Jean Dessens Roberto Fraile 《Atmospheric Research》2007,83(2-4):493-504
This paper is a comparative study between the two most common hailpad calibration systems: one annual calibration of a whole consignment of material, and the individual calibration of each plate after a hailfall. Individual calibration attempts to minimize errors due to differences in sensitivity to the impact of hailstones between plates from the same consignment, or due to differences in the inking process before the actual measurement.The comparison was carried out using calibration data from the past few years in the hailpad network in south-western France, and data from an individual calibration process on material provided by the hailpad network in Lleida (Spain). The same type of material was used in the two cases.The results confirm that the error in measuring hailstone sizes is smaller in the case of an individual calibration of hailpads than when one single calibration process was carried out for a whole consignment. The former is approximately 80% of the latter. However, this error could have been higher if it had not been the same person carrying out the single calibration process and the measuring of the dents: it has been found that differences in the inking process may account for up to 20% of the error in the case of small hailstones. Calibration errors affecting other variables, e.g. energy or parameter λ of the exponential size distribution are generally higher (5% and 18%, respectively) than errors due to the spatial variability of the hailstones. However, the calibration method does not influence the maximum size, since the relative error attributed to the spatial variability is about 8 times the calibration error.In conclusion, if errors in determining energy or parameter λ are to be reduced to a minimum, it is highly advisable to be consistent in applying the measuring procedure (if possible with the same person carrying out the measurements all the time), and even to use individual calibration on each plate, always bearing in mind that technicians have to be trained appropriately in order to achieve the highest possible degree of uniformity. 相似文献
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重叠函数的校准对地基激光雷达低空大气探测的准确性至关重要。目前被广泛用于校准拉曼激光雷达重叠函数的双通道实验标定法,需要满足弹性散射通道与氮气拉曼散射通道的重叠函数近似相等的前置条件。但实际仪器光路往往会偏离理想状态,使得该前置条件无法得到满足,导致校准失败。本文使用光线追踪法模拟重叠函数,计算了各种光路失调情况下弹性散射通道与氮气拉曼散射通道的比值,并引入了一种镜头遮蔽实验来评估双通道实验标定法的前置条件是否得到满足。数值模拟结果表明,当雷达接收面的不同象限被遮蔽时,如果弹性散射通道与氮气通道的信号强度比值基本保持不变,则满足前置条件;如果弹性散射通道与氮气通道的信号强度比值有显著差异,则可判定仪器光学系统失调,需要调整直至满足上述前置条件时才能使用双通道实验标定法标定。利用该方法对南京市气象局安装的拉曼激光雷达进行了光路测评和调整,并与CCD(charge-coupled device)侧向成像激光雷达观测信号做对比,结果显示调整后的定标效果更好。 相似文献
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Amin Haghnegahdar Bryan A. Tolson Bruce Davison Frank R. Seglenieks Erika Klyszejko Eric D. Soulis 《大气与海洋》2014,52(4):281-293
This paper reports on recent progress towards improved predictions of a land surface-hydrological modelling system, Modélisation Environmentale–Surface et Hydrologie (MESH), via its calibration over the Laurentian Great Lakes Basin. Accordingly, a “global” calibration strategy is utilized in which parameters for all land class types are calibrated simultaneously to a number of sub-basins and then validated in time and space. Model performance was evaluated based on four performance metrics, including the Nash-Sutcliffe (NS) coefficient and simulated compared with observed hydrographs. Results from two calibration approaches indicate that in the model validation mode, the global strategy generates better results than an alternative calibration strategy, referred to as the “individual” strategy, in which parameters are calibrated individually to a single sub-basin with a dominant land type and then validated in a different sub-basin with the same dominant land type. The global calibration strategy was relatively successful despite the large number of calibration parameters (51) and relatively small number of model evaluations (1000) used in the automatic calibration procedure. The NS values for spatial validation range from 0.10 to 0.72 with a median of 0.41 for the 15 sub-basins considered. Results also confirm that a careful model calibration and validation is needed before any application of the model. 相似文献
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FY-2B与NOAA卫星红外通道的相对定标 总被引：2，自引：0，他引：2
FY-2是自旋扫描静止气象卫星,其红外通道的在轨定标是将黑体从后光路插入目标光路中进行的,此种定标不是全光路定标,存在较大的误差。为了获得较好的红外通道在轨定标系数,用定标精度较高的NOAA(16,17)卫星通道4观测数据与FY-2B红外通道观测数据进行了相对定标试验。相对定标的工作主要是两种卫星观测仪器响应函数之间的光谱匹配和观测图像之间的几何匹配。拟合匹配后两种卫星的观测数据,利用NOAA卫星较高精度的定标系数可得到改进的FY-2B定标系数。FY-2B相对定标系数的精度比原定标系数有较大的提高。 相似文献
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四川省气象自动站蒸发要素校准工作中示值波动过大的情况时有发生,误差时而满足校准规范要求,时而不满足规范要求,导致校准数据的重复性较差,面对这种情况,按照中国气象局监测网络司发行的自动气象站现场校准方法(试行),难以对测量系统计量性能指标的符合性做出判定。通过查阅JJF1001-2011《通用计量术语及定义》、JJF1126—2004《超声波测厚仪校准规范》等相关资料,得出规定测量系统的示值重复性即可解决这一技术难题,并且通过大量试验及工作经验得出了示值重复性指标及其校准方法,为自动站蒸发系统现场校准规范的制定提供了有力的理论依据。 相似文献
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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。 相似文献
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Dario Camuffo 《Climatic change》2002,53(1-3):297-329
Calibration and instrumental errors of early thermometers are analysed. The first concepts, the development of scientific ideas, the main problems linked to the construction of early thermometers and the calibration are considered in order to evaluate errors. The operating principle of the `constant-volume' air thermometer is presented andits limits are discussed. The theory shows that for an ideal Amontons' thermometer, only one calibration point is sufficient from which the other can be calculated; it is therefore possible to determine the difference from an ideal instrument. A comparison is made between calibrations and instruments made by G. Amontons (1699), G. Poleni (Venice, 1709; Padova 1725), and J.H. Lambert (1779). Amontons' thermometer needs to be integrated with a barometric reading; an important error arises from the different density of mercury during calibration and usage. The calibration was made in winter and at the upper point the thermometer was at 100 ° C, while the barometer remained near 0 ° C. However, field observations were made with both instruments at the same temperature and this caused an error that in the cold season is negligible, but in the hot season reaches 1 ° C. Problems connected with the calibration and scale linearity are discussed in view of the beliefs of the time and the operative methodologies used in early meteorology. Emphasis is given to comparability of different instruments, thermometric scales and calibration methodologies used in Padova in the 18th century for Amontons' Poleni's, Fahrenheit's, Réaumur's and Delisle's thermometers. The instrument supports and the incision of the scale were subject to expand or contract depending on temperature or humidity changes, and this was a source of error that can be corrected with the help of observed or estimated data. Problems linked to the construction of thermometers have been evaluated, as well as the linearity of displacements of the thermometric liquid, or the drift due to ageing and transformation of the thermometric liquid, the glass or the support. All these errors have been evaluated and some of them have been found negligible, but some are of the order of 0.5 ° C. The quantitative resultsobtained here can also be usefully applied to correct and validate other long series. 相似文献
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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。 相似文献
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T213 降水预报订正系统的建立与研究 总被引：5，自引：0，他引：5
目前T213降水预报存在一定程度上的系统性误差,为了更好地使用T213降水预报产品,减小系统性误差对主观预报的影响,利用一种统计学方法可以对T213降水预报进行订正,减小T213降水预报的系统性误差。通过对2004年6—11月订正前后的T213降水预报进行统计学和天气学检验分析,检验该订正系统的订正效果。结果表明,订正后的降水预报的预报偏差B值有了显著改善,其他统计检验量也有了不同程度的提高;订正后雨带的位置和轮廓更加接近降水实况。 相似文献