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FY-2C云迹风资料在中尺度数值模式中的应用研究 总被引:6,自引:1,他引:5
利用探空观测资料对FY-2C云迹风资料进行统计检验和误差分析,并针对其误差特征进行偏差订正和热成风原理两种方法的质量控制.然后通过GRAPES-3Dvar同化到GRAPES-Meso模式中,对2005年7月1日00时至7月2日00时发生在中国西北部的一次暴雨过程进行了数值对比试验.结果表明:云迹风数量在垂直方向上主要集中分布于500 hPa以上的对流层中高层,在250 hPa附近数量分布概率最大;高度在500 hPa以下云迹风存在明显的风向误差和很大的风速误差,而且误差分布发散,可用性较差.500 hPa以上层次的云迹风误差较小,且误差分布呈高斯分布具有一定的系统特性,可用性较好;通过质量控制后,可以把风向错误或风速偏差太大的云迹风予以剔除,进一步提高云迹风的精度;同化云迹风资料后,在暴雨区附近初始风场低层的西南气流明显加强,有利于暴雨区水汽输送和水汽辐合,最终能很好地改善24 h暴雨预报的强度和落区. 相似文献
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对利用静止气象卫星云导风系统生成的云迹风资料与无线电探空风资料对比分析 ,估计云迹风资料的可靠性与精度。选取2001年5~7月间12天共16个时次的资料 ,采用临近层比较法 ,对气象卫星的红外图像云迹风与水汽图像的轨迹风计算结果分别与探空风进行对比分析 ,水汽图像的导风效果略好于红外图像。把云迹风矢和探空风矢分为高、低空两层 ,分别统计给出高、低空云迹风的误差 ,在高空 ,风速误差大、风向误差小 ;在低空 ,风速误差小 ,风向误差大。对卫星云迹风与无线电探空风的最佳层比较 ,在最佳层的风速误差均方根与风向差绝对平均值均明显地减小。 相似文献
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对基于雷达反射率因子观测数据的层状云降水粒子谱参数反演算法进行研究。(1)给出层状云降水粒子谱参数的反演理论和反演算法流程;(2)选取吉林省伊通县的一次降水层状云过程进行反演试验和验证分析,利用雷达反射率因子观测数据反演得到雨滴平均直径和数浓度参数,并用放置在伊通县气象局观测场中的Parsivel激光雨滴谱仪的实测数据与近地层反演结果进行对比。结果发现,通过反演算法计算得到的滴谱与实测滴谱的变化趋势基本相同,而且反演的雨滴平均直径和数浓度在量级和数值上的大小与实测数据具有良好的一致性,说明该反演方法用于从现有天气雷达回波强度数据中挖掘出降水性层状云的微物理参数是可行的。 相似文献
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FY-2E云迹风资料的高度调整对“灿都”(1003)台风路径数值预报影响的研究 总被引:4,自引:2,他引:2
首先分析了FY-2E云迹风资料在不同高度上的分布,并利用背景场信息对云迹风资料的高度进行整体调整,然后进行数值对比试验,即将高度调整前和高度调整后的云迹风资料分别同化到GRAPES-3DVAR系统中,比较分析同化这两种资料对2010年7月21日0000 UTC—23日0000 UTC的台风路径预报的影响。结果表明,在垂直方向上,500 hPa以上才有云迹风资料,大约在300 hPa的资料最多;文中提出的重定高方法能有效地重新调整云迹风资料的高度,调整后的云迹风分布没有明显的矛盾,分布合理;同化重定高后的云迹风资料后,尤其是水汽通道的云迹风资料,能合理地对初始风场进行调整,使"灿都"台风周围的引导气流有利于其向实测路径靠近,进而有效改进台风路径预报。 相似文献
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逐时云迹风资料同化对暴雨预报的模拟试验 总被引:5,自引:1,他引:4
文中基于不同的云迹风同化方案,用GRAPES模式对2005年7月11-12日长江中下游一次暴雨强降水过程进行了云迹风资料同化试验及数值模拟,通过对比分析不同方案所得的分析场及预报场的差异,研究逐时云迹风资料三维变分同化对分析场及暴雨预报的影响.首先,根据连续性原理及双通道各层次云迹风资料的误差分析,分3个步骤对7月11日00:00-12:00 UTC共12个时次的双通道云迹风资料进行了初步的质量控制;然后,把经过质量控制的云迹风资料放入基于GRAPES 3D-VAR三维变分同化方案开发的逐小时循环同化系统中进行同化,将得出的分析场与单一时次未经质量控制的云迹风资料同化得出的分析场进行对比,探讨了逐时云迹风资料同化对数值预报分析场的影响;最后,把同化后的分析场作为初始场,用 GRAPES模式对 2005年7月11-12日长江流域暴雨过程做24 h降水预报试验,分析两个同化方案所模拟得到的预报场的差异.结果表明,经资料的筛选、同经纬度单点通道的选择及资料的稀疏化3个步骤控制后,各层次云迹风资料的误差有明显减小;加入经质量控制的逐时云迹风资料其三维变分同化可以提高分析场中风压场及水汽场的质量;而且在暴雨预报试验中可以相对更准确地预报暴雨落区及雨强. 相似文献
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FY-2C云迹风资料同化应用对台风预报的影响试验研究 总被引:3,自引:2,他引:1
针对0505号台风“海棠”, 采用WRF区域中尺度模式进行控制试验和两个同化试验, 利用WRF-3DVAR同化系统同化FY-2C红外和水汽两个通道云迹风反演产品, 同化分云迹风经质量控制和未经质量控制两组同化试验。通过三组试验分析云迹风资料对降水和风场等的预报结果的影响, 并进行24小时降水量分级Ts评分检验以及风场点对点检验。结果表明: 同化经质量控制云迹风资料可以提高降水落区和强度预报的准确度, 不同等级的Ts评分较其它试验都有较明显改进; 风场预报模拟也有所改善。增加两例台风, 使用与“海棠” 相似的处理方法进行模拟试验, 并对模拟结果24小时降水分析与检验, 得到与“海棠”类似结论。因此, 经过合理性选择的云迹风资料的加入, 有利于补充初始场中可能未包含的中尺度信息, 从而提高试验中对于降水、风场等的模拟效果, 提高WRF模式的模拟预报能力。 相似文献
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Abstract Cloud‐motion winds measured from organized and disorganized cumulus cloud fields are compared with winds measured at collocated buoys in the northeast Pacific Ocean. Findings suggest that an automated tracking algorithm using GOES satellite imagery can measure cloud‐level winds at these latitudes. Comparisons with buoy wind measurements show that the influence of boundary‐layer stability should be included in estimates of surface winds from cloud‐motion data. 相似文献
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H. Jean Thiébaux 《大气与海洋》2013,51(4):291-305
Abstract Data assimilation in numerical weather forecasting corrects current forecast values by subtracting a portion of interpolated forecast‐minus‐observation differences at the points of a three‐dimensional grid. Deviations used in updating a forecast data field are forecast errors obtained or derived from observations available at update time. When observations are missing at mandatory levels, construction of full vertical soundings by interpolation introduces extraneous errors. The present paper is concerned with determination of the error in vertical extrapolations of surface winds, and of aircraft and satellite cloud‐tracked winds. In addition it examines the effect on accuracy of using location‐specific statistics compared to averaged statistics as the basis for the interpolation weighting scheme and compares errors of one‐ and two‐variable interpolations. Interpolation accuracy tests demonstrate the influence of the interpolation scheme on the quality of interpolated information used in forecast updating. The results show that the level of accuracy exceeds the benchmark provided by monthly mean forecast error values only with bivariate interpolation of wind components from off‐level data sources. 相似文献
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半透明云风矢量高度指定是卫星风矢量算法的重要部分,需要使用来自半透明云体的辐射和云下背景辐射两个变量。为了更精确地获得来自半透明云体的辐射,采用像元对追踪相关系数的贡献和红外亮温两个变量进行统计分析,将追踪图像块中的像元分为3个部分:小贡献像元、暖区段大贡献像元和冷区段大贡献像元;对暖区段、冷区段内大贡献像元的特征进行考察表明,冷区段的大贡献像元更能代表追踪图像块运动,称为代表运动像元。选择代表运动像元参与计算来自半透明云体的辐射,对半透明云风矢量高度指定算法进行改进,在该算法中分别使用和不使用代表运动像元,计算FY-2气象卫星风矢量,将结果与欧洲中期天气预报中心(ECMWF)分析场进行对比表明,在半透明云高度指定算法中使用代表运动像元,FY-2气象卫星风矢量误差明显降低。 相似文献
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A statistical study of GMS low cloud winds in January,April,July and October,1983 shows that on an average,there exist 223.5 low cloud winds over western North Pacific each synoptic time.The low cloud winds have a diurnal change with more low cloud winds at 12 Z than at 00 Z. The wind fields at 850 hPa over western North Pacific,with and without application of low cloud winds, have been analyzed by a successive correction scheme.The results indicate that the flow patterns without low cloud winds are considerably distorted from short of wind data over the oceanic region.On the contrary,with application of low cloud winds,the flow patterns get much more improved over the oceanic region. 相似文献
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During summer Monex-79, a variety of observing systems viz. research ships, research aircrafts, constant pres-sure balloons and geostationary satellite etc. were deployed, besides the regular conventional observations The pur-pose of these additional systems was to make the best possible data for the studies on various aspects of monsoon cir-culation. The present study is aimed at the construction of vertical wind profile using cloud motion vectors obtained from GOES (I-O) satellite and to examine whether the constructed wind profiles improves the representation of the monsoon system, flow pattern etc. in the objective analysis. For this purpose, climatological normals of the wind field are considered as the initial guess and the objective analyses of the wind field are made with, first using only data from conventional observations over land areas, subsequently including the constructed winds from cloud motion vectors. These analyses are then compared with the standard analyses of wind field obtained from Quick Look Atlas by T. N. Krishnamurti et al. (1979).It is inferred that satellite estimated mean wind profiles show good agreement with the mean wind profiles of the research ships with RMS errors less than 5 mps below 500 hPa and less than 8 mps above 500 hPa. It is further infer-red that the inclusion of constructed winds shows a positive impact on the objective analysis and improvement is seen to be more marked in the data-sparse region of the Arabian sea. Analyses which include the constructed winds show better agreement with the standard analysis, than the analyses obtained using only conventional winds. Thus, results of our study suggest that the wind profiles constructed using cloud motion vectors are of potential use in objective analysis to depict the major circulation features over the Indian region. 相似文献
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Cloud motion data were compared to ship observations over the Indian Ocean during the summer monsoon, 1 May to 31 July 1979, with the objective of using the cloud data for estimating surface wind and ultimately the wind stress on the ocean. The cloud-ship comparison indicated that the cloud motions could be used to estimate surface winds within reasonable accuracy bounds, 2.6 m s-1 r.m.s. speeds and 22° to 44° r.m.s. directions (22° r.m.s. for winds < 10 m s-1). A body of statistics is presented which can be used to construct an empirical boundary layer with the eventual goal of producing a stress analysis for the summer MONEX from cloud motion data. 相似文献
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多普勒天气雷达VAD(Velocity Azimuth Display)风廓线资料可以提供高时间分辨率的高空风场信息。本文针对中国雷达VAD风廓线资料,设计发展了面向资料同化应用的NMIC(国家气象信息中心)质量控制方案,该方案改进了NCEP(国家环境预报中心)方案中存在的问题。利用2020年2—8月的L波段秒级探空风场资料,分别对比质量控制前、经过NCEP质量控制方案、以及经过NMIC质量控制方案的VAD风廓线资料,统计分析结果表明经过NMIC质量控制方案的VAD风廓线资料最接近观测,准确度最高,并且在各个高度上其偏差和均方根误差最小,充分说明了NMIC质量控制方案的有效性。相对背景场偏差分析表明,经过NMIC质量控制方案的VAD资料偏差和均方根误差最小,与背景场的偏差更接近高斯分布,更能满足资料同化的要求。本文的研究有助于推进VAD风廓线资料在数值预报科研和业务中的应用。 相似文献