超低仰角扫描改进雷达观测台风的探讨

利用长乐雷达超低仰角探测资料,对比分析了台风"海棠"和"蔷薇"的超低仰角和0.5°仰角PPI回波资料的差别。结果表明,在不受或尽量少受地物影响的情况下,雷达合理选用超低仰角探测是可行的,且在低层降水回波探测方面效果较0.5°仰角好,特别在远距离探测能力方面有明显改进,一般在距离>100km后探测能力较0.5°仰角有明显优势。雷达超低仰角反映出的台风云块的分布比较清晰,雷达加入超低仰角探测对台风低层探测和预警有一定程度的改进。降低0.12°后的超低仰角探测可提前台风预警时间和提早约2～6个体扫;提高台风探测范围约1.09倍,其他几次体扫的对比情况也反映出降低仰角,0.31°仰角比0.48°仰角提高台风"蔷薇"探测范围约为2.1%～9.6%。雷达超低仰角提高探测台风云体低层结构的同时,更易受近距离海浪杂波的影响,海浪杂波有时可能干扰对台风结构的判断,应引起注意。在选取多大的超低仰角时,应兼顾二者关系。

Typhoon Detection of Radar Improved Using Ultra Low Elevation Angle

Using the ultra-low-elevation angle data of changle radar,the ultra-low-elevation of typhoon ’Haitang’ and ’Jangmi’ and difference of PPI echo with 0.5° elevation angle are analyzed.The obtained results are as follows:(1) It can improve the remote detection,judge the construction and evolution of typhoon.(2) It can help to forecast the intensity and development of typhoon,improve the early warning system and nowcasting.(3) It can help to find out the development and change of typhoon cloud system.For the typhoon ’Jangmi’,comparing with 0.5° elevation angle,the remote detection area has been enhanced for 1.09 times,the total estimated precipitation increase between 2.1%～7.9%.Ultra-low-elevation angle can improve the weakness of routine scan way on detecting ability of remote low radar echo.In the meantime,the ultra-low-elevation angle is also vulnerable to detect the impact of close-wave clutter,judgment the construction of typhoon can be interfered sometimes.Through radar detecting of typhoon the ’Haitang’ and ’Jangmi’,the ultra-low-elevation angle can improve the remote detection and early warning of typhoon.