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

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.