X波段双线偏振雷达不同衰减订正方法对比及其对降水估测影响研究

Comparison of different attenuation correction methods and their effects on estimated rainfall using x-band dual linear polarimetric radar

中文关键词:  X波段双线偏振雷达，衰减订正，降水估测

英文关键词:X-band dual linear polarimetric radar, attenuation correction, method, rainfall estimate, method

中文摘要:

      本文分析了X波段双线偏振雷达衰减订正各种方法的特点，考虑到差传播相移率 作为衰减订正的一种有效途径，以及由于 值较小，数据质量不稳定，往往导致订正误差较大，因此提出了同时利用水平反射率因子 与差传播相移率 进行衰减订正的 综合法。基于同样的考虑，在随后利用 、 进行降水估测时，提出了 综合估测方法。利用中国科学院寒区旱区环境与工程研究所和成都锦江电子系统工程有限公司，在研制3.2cm波长同时收发式多普勒偏振天气雷达过程中，2005年8月在平凉外场试验取得了一批观测资料，对提出的衰减订正综合法及降水估测综合法的效果进行了分析检验，结果表明， 综合法对 、 有稳定的订正效果，并且订正速度快，能够达到实时运行的要求。2005年8月11日从15:08:03--22:05:46，间隔5-12分钟不等，雷达开机取得了连续的观测资料，通过对这次降水过程的对比分析表明， 综合估测法比单因子 法、 关系法，适用估测的降水强度变化范围广，与自动雨量记的观测结果较为吻合。 关系法中，利用订正后的 值，比利用订正前的 值，降水估测值与雨量记实测值的误差明显减小，说明衰减订正后的雷达数据质量有明显的改善。

英文摘要:

       Except its smaller antenna, mobile convenience and low cost, X-band radar has a higher resolution than the S-band’s, and C-band’s, and therefore can therefore detect more subtle microphysical processes information of clouds, raindrop, hail and hydrometeor etc. As an effective complementarity of new generation weather radar network, it can be widely applied to the monitoring and warning of disastrous weather such as heavy rain and hails, the operations guidance and effect evaluation of weather modification, and the managements of reservoir, urban area and aviation etc., therefore, it has a huge potential in the remote sensing of clouds and precipitation and in nowcasting. Compared to ordinary Doppler weather radars, dual polarimetric radar have a very distinct advantage in the quantitative estimation of precipitation, however, the radar signal attenuation is an important shortcoming which hampers the wide application of X-Band radar, especially in precipitation estimate. Various kinds of signal attenuation correction methods for X-band dual linear polarimetric radar are analyzed, the specific differential phase shift is considered as an effective approach on attenuation correction. However, the values of for light rain are too small, which results in instable quality and larger error, therefore, reflectivity and specific differential phase shift are combined together in the method to correct the attenuation error. Based on the similar consideration, combined technique is also suggested when and are used to estimate rainfall. During the development stage of the synchronous transmitting and receiving dual polarimetric Doppler weather radar with 3.2 cm wave length by the Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences and Jinjiang Electronic System Engineering Co., Ltd. Chendu, a set of observational data were obtained in the field experiment in Pingliang in August 2005. By means of the set of observational data, the effect of combined attenuation correction and rainfall estimation methods are examined, the results indicate that the combined method is effective in correcting and , and furthermore, the correction speed is able to meet the requirement of real time operations. Some continuous detection records with the 5-12 minute intermission were gained in the time period of 15:08:03--22:05:46 BST August 11, 2005. The contrastive analysis of this precipitation process show that combined estimation technique is better than single factor methods such as or , more suitable when the precipitation intensity varies widely, and the estimated results is in good agreement with automatic rain-gauge records. As to the relation, the deviations between precipitation estimations and available rain-gauge measurements decrease obviously when the corrected is used, indicating that the radar data quality are obviously improved after the attenuation correction.