| 雷达回波垂直廓线及其生成方法 |
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| 引用本文： | 吴翠红 万玉发 吴涛 金鸿祥. 雷达回波垂直廓线及其生成方法[J]. 应用气象学报, 2006, 17(2): 232-239 |
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| 作者姓名： | 吴翠红 万玉发 吴涛 金鸿祥 |
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| 作者单位： | 1.南京大学大气科学系, 南京 210093 |
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| 基金项目： | 湖北省科技攻关计划课题(2004AA306B01)，湖北省国际科技合作课题(2005CA012)，湖北省气象局科技发展基金项目(2003ZZ01)共同资助。 |
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| 摘 要： | 研究雷达回波Z (R) 垂直廓线VPR有两个重要内容: 一是VPR的生成方法, 二是用VPR订正雷达估算降水的技术。在简要比较现有生成方法———参数法、平均法和识别法的主要特点后, 认为平均垂直廓线MVPR具有简便、实用的优点。文章着重对MVPR的生成方法作了细致的探讨, 形成了4种生成算法, 并作了比较; 展示了各种生成参数对MVPR的不同作用, 并简要介绍了一个应用程序框图。对两个降水实例实施订正后初步评估表明, 用MVPR订正雷达估算降水可使评估因子R/G从0.84 (0.86) 提高到0.93 (0.97), 而绝对误差率则下降4%。
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| 关 键 词： | 雷达回波垂直廓线 VPR生成方法 降水订正 |
| 收稿时间： | 2005-05-16 |
| 修稿时间： | 2005-11-04 |
Vertical Profile of Radar Echo and Its Deteermination Methods |
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| Wu Cuihong,Wan Yuf,Wu Tao,Jin Hongxiang. Vertical Profile of Radar Echo and Its Deteermination Methods[J]. Journal of Applied Meteorological Science, 2006, 17(2): 232-239 |
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| Authors: | Wu Cuihong Wan Yuf Wu Tao Jin Hongxiang |
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| Affiliation: | 1.Department of Atmospheric Science, Nanjing University, Nanjing 2100932.Wuhan Central Weather Office, Wuhan 4300743.Institute of Heavy Rain, China Meteorological Administration, Wuhan 4300744.Shiyan Meteorological Bureau, Hubei Province, Shiyan 442000 |
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| Abstract: | Radar beam's lifting and widening in the distance and the vertical nonuniformity of the natural distribution of water content in the atmosphere are important factors of radar detecting rainfall errors. During 1980s—1990s, the importance of vertical profile of reflectivity (VPR) to radar detecting rainfall is emphasized and the study on the VPR technology is conducted. There are two major aspects on the researches of VPR, one is the determination method of VPR, the other is the technique to correct radar precipitation estimation. After comparing the major features of three existing determination methods, i.e., parameterization, averaging and identification, it is found that the mean vertical profile of reflectivity (MVPR) has the advantage of simplicity and utility. Four algorithms of MVPR are obtained and compared with emphasis on investigating the determination method for mean vertical profile (MVPR); and the different functions of determining parameters, especially for MVPR, are demonstrated. Results show that the R/G ratio can be enhanced from 0.84 (0.86) to 0.93 (0.97) and the AD of radar rainfall estimation can decrease by 4% after the MVPR correction in the two precipitation cases.Among the four algorithms of MVPR, M11 is the best one in which the ratio profile takes the near groundlevel as the datum plane so that the feasibility of radar precipitation correction can be assured, and it has better representation owing to consideration of the same weighing of each bin in domain D. The MVPR algorithms relate to 8 attribute parameters, of which some values exert significant effect on the quality of MVPR. For example, the initial distance Ds in domain D obviously affects the profile shape below 1 km, therefore 1~5 km should be adopted; the distance outside D0 domain D plays its role from near ground-level to 6 km and the smaller D0, the smaller the more smoothing due to the beam widening, so 40~50 km should be adopted; the smaller the value of the vertical piecewise-height Δh, the more detailed the profile shape, so 250 m should be adopted. The evidence also indicates that when the exponent b in the different Z-R relationships are kept constant, the slope of the profile below 1.5 km will increases and the bright band of the profile will be more distinguishable with the decrease of the coefficient A.By analyzing VPR derived from the volume data in terms of VCP21 model of CINRAD/SA in Wuhan, it is found that the bright band locates at the height of 5 km and the radar precipitation estimation is generally not affected by the bright band when using 0.5° reflectivity PPI (or hybrid scan) within radius of 200 km. When echoes of major precipitation system in domain D, Z (R) below the bright band decreases with the height (dZ/ dh < 0), and these may be the causes why radars underestimate summer rainfall (especially for long distance) in the middle reaches of the Yangtze and it could be done by means of VPR to correct the radar precipitation estimation. |
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| Keywords: | radar echo vertical profile VPR determination method precipitation correction |
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