C波段高山天气雷达对森林火灾的探测能力初析

Preliminary Analysis of the Ability of C-Band Mountaintop Radars to Detecting Forest Fires

借鉴前人在S波段新一代天气雷达上探测森林火灾和城市大火烟尘的方法和研究成果,利用收集到的云南十部C波段新一代天气雷达的34次森林火灾个例资料,立足云南C波段高原高山雷达的一些特点,采用分类对比进行分析研究,得出C波段高山雷达森林火灾回波的一些特有指标。提出按雷达海拔高度分别设置森林火灾判别阈值、引入速度场特征、降水回波过滤等一些新指标和方法,进行这类地区的雷达森林火灾探测。随后开展了业务实践,经检验和实地踏勘,取得了一定效果。证明C波段雷达同样具有一定的探测森林火灾回波的能力,主要技术指标有:高山雷达由于海拔高差的影响,应分别针对不同雷达设置相应的阈值参数;根据森林火灾回波的上升和飘散特性,雷达回波速度场与周围回波有时呈现出一定差别;采用过滤晴空回波、过滤杂波、过滤地物回波、过滤二次回波、过滤降水回波、识别速度场特殊回波等办法,可得到滤出的火灾烟尘疑似回波。这些指标和方法对西部高山雷达探测应有一些参考作用。

Based on the methods and results of previous researches on detecting forest fires and urban fire smoke by S-band Doppler weather radar as well as the classification and comparison of 34 forest fire cases from 10 C-band radars in Yunnan Province,some unique indices of forest fire echoes by C-band mountain-top radars were obtained in this paper.The paper also put forward setting forest identification threshold according to radar altitude.Some new indices and methods,such as velocity field features,precipitation echo filtering,are introduced to detect forest fires.Then conducting radar detection to forest fires in such kinds of areas and operational practices proved to have achieved certain results by practical tests and field surveys.The main technical indices are as follows.Due to the effect of altitude difference of mountain radars,correspondly indices and parameters of different radars should be set respectively.According to the rising and drifting characteristics of forest fire echoes,the radar echo velocity is different from the surrounding echoes sometimes.By filtering clear air echo,clutter,ground object ehco,secondary echo,precipitation echo and identifying special echoes of velocity field,the suspected echoes of fire smoke can be obtained.These indices and methods could be used as reference for radar detection in the western mountains.