【摘要】 2005年7月19日08时~20日08时"海棠"(Haitang)台风登陆福建省前后24小时期间,带来一次明显降水过程,且台风北侧降水较南侧强,呈明显非对称分布。利用WRF模式对此次降水过程进行了数值模拟,基于模拟结果,不仅分析研究了相对湿度、垂直上升运动场,同时还进行改进的湿Q矢量诊断分析,以及计算分析地形抬升和地表摩擦的强迫作用,定量分析"海棠"台风降水非对称分布特征形成的可能成因。结果表明:(1)WRF模式成功地模拟出了此次降水非对称分布特征、主要降水落区,以及300 mm以上极端强降水的强度、位置,模拟效果令人鼓舞。(2)垂直上升运动条件可能是造成降水非对称分布特征的主要因素。(3)台风北侧改进的湿Q矢量散度辐合强度明显较其南侧强,进一步计算分析发现,改进的湿Q矢量散度强迫产生的降水场也呈明显非对称分布,且台风北侧强于南侧。(4)地形因子强迫产生的降水强度约是改进的湿Q矢量散度强迫产生的降水强度的1.6~2.5倍,且地表摩擦作用强迫产生的降水强度约是地形抬升作用强迫产生的降水强度的2~3倍。更多还原

【Abstract】 Typhoon Haitang landing Fujian Province from 0800 LST 19 July to 0800 LST 20 July in 2005,gives rise to a significant rain process during the 24 hours,and precipitation intensity on the north side of typhoon is stronger than that on the south side,which shows obvious asymmetric distribution.The rainfall process is simulated using the WRF model and based on simulated outputs,the relative humidity and vertical ascending motion fields are analyzed,meanwhile,the forcing roles of orgoraphic lifting and surface friction are calculated and the diagnosis of the revised wet Q vector is conducted,so the cause of asymmetric distribution formation of rainfall associated with typhoon Haitang is analyzed quantitatively.The results are as follows:(1) The rain asymmetric distribution feature,the fallout region of primary precipitation,and the intensity and the location of extreme rain exceeding 300 mm are simulated successfully,so the simulation effects are considerably inspiring.(2) Vertical ascending motion condition may be the predominant factor leading to asymmetric distribution of precipitation associated with the typhoon.(3) The convergence intensity of the revised wet Q vector divergence on the north side of the typhoon is stronger than that on the south,and from the further calculation and analysis it is found that the rain field forced by the revised wet Q vector divergence also shows marked asymmetric distribution,with intensity on the north stronger as compared with that on the south side of the typhoon.(4) The precipitation intensity forced by orographic factors is about 1.6-2.5 times of the counterpart caused by the revised wet Q vector divergence,and the rain intensity forced by surface friction is approximately 2-3 times of the counterpart caused by orographic lifting.更多还原