【作者】 庄薇；

【导师】 刘黎平；

【作者基本信息】 南京信息工程大学 ， 大气物理学与大气环境， 2013， 博士

【摘要】 雷达估测降水一直是一个非常复杂的问题,在雷达覆盖较好的平原地区,雷达降水估测方面的研究相对比较成功。而对地形复杂的青藏高原,雷达降水估测面临着巨大的挑战：第一,青藏高原地形复杂,常规基于地形的混合扫描方法由于树、建筑物等不在地形数据中,而造成混合扫描仰角的计算误差。第二,青藏高原海拔高,零度层低,不得不用零度层亮带及以上固态降水区域的资料估测降水。用常规的估测液态降水的Z-R关系不适合于估测青藏高原固态降水或受亮带影响的降水。第三,青藏高原雨量计非常稀少,无法用常规对雨量站密度要求较高的雨量计校准方法。为了解决以上这些青藏高原降水估测的难点和问题,本文利用青藏高原上的雷达、雨量计资料,通过以下三方面的研究,来提高青藏高原降水估测精度。第一,研究基于反射率气候学的混合扫描仰角计算方法,避免由于地形数据不包括树、建筑物等产生的误差；第二,在考虑雷达最低几层仰角受遮挡的情况下,利用反射率垂直廓线和亮带识别订正参数,对亮带区进行订正,减小零度层亮带对降水估测的影响；针对不同降水类型(零度层以上固态降水、零度层以下液态降水、受亮带影响区降水),提出相应的Z-R关系。第三,研究适合于雨量计稀少地区,对雨量计密度要求不高的雨量计校准方法。这对研究青藏高原云和降水在能量和水分循环中的作用,验证各种卫星遥测青藏高原云和降水的方法以及山洪泥石流等灾害性局地强降水的准确及时的预报都有重要意义。更多还原

【Abstract】 Radar precipitation estimation is a very complicated issue, and the research on it is relatively successful in the plains with better radar coverage. However, regarding to the complex terrain of the Tibet Plateau, radar precipitation estimation faces big challenges:firstly, due to its special geographical environment, the ground clutter of the Tibet Plateau has some differences from any other parts of that in the past, so the previous ground identification algorithm is not suitable for the Tibet Plateau. Secondly, the Tibet Plateau is in complex terrain, because of trees, buildings and others are not in terrain data, the conventional terrain-based hybrid scan method will result in calculation error of the hybrid scanning elevation. Thirdly, since the Tibet Plateau has high sea level and low zero layer, then it has used the information for the bright band of the zero layer and the solid-state precipitation region over it for precipitation estimation. However, as the lowest layers of radar elevation are blocked, and bright band identification of the revised methodology (for plains with better radar coverage) of zero layers in complex terrain is not with good correction effect, the improvement in precipitation estimation is not obvious. The conventional precipitation classification of convective and stratiform clouds and their corresponding liquid precipitation of Z-R relationship are not fit for estimation of solid-state precipitation or precipitation influenced by bright band over the Tibet Plateau.In order to solve the difficulties and issues of precipitation estimations over the Tibet Plateau, this paper uses the radar on the Tibet Plateau, and rain gauge data to improve the precipitation estimation accuracy over the Tibet Plateau through the study of the following four sections.1). Propose the ground clutter identification parameters fits for the Tibet Plateau according to the ground clutter characteristics, and uses the fuzzy logic methods to identify ground clutter of the Tibet Plateau;2). Study the hybrid scan elevation calculation based on reflectivity climatology, so as to avoid any error produced as the terrain data does not include trees, buildings and other things;3). Regarding that the lowest layers of radar elevation are blockage, use the vertical profile of reflectivity bright band to make the identification of the revised parameters, and correct the bright band so as to reduce the impact of the bright band on precipitation estimation;Put forward the corresponding Z-R relationship for different types of precipitation. This has an important significance for research on roles of clouds and precipitation over the Tibet Plateau in the aspects of energy and water cycle, and to verify various methods of satellite remote sensing of cloud and precipitation over the Tibet Plateau as well as accurate and timely forecasts of heavy local precipitation because of debris flow and other disastrous.更多还原