WRF中尺度模式对两个沿浙江近海北上热带气旋的预报分析

Forecast Analysis by WRF Model on Two Tropical Cyclones with North Track along the Zhejiang Coast

结合宁波市气象台业务运行WRF中尺度模式,对2011年2个沿浙江近海北上的热带气旋"米雷"和"梅花"的预报进行对比分析。结果表明,模式对"米雷"和"梅花"在浙江省气象站点预报降水与实况相关系数分别为0.617和0.478。降水分级TS评分表明,模式对"米雷"的预报效果好于"梅花",主要由于"梅花"空报率过高,模式对这2个热带气旋20 mm以上的降水误差主要出现在浙江东部特别是沿海地区,呈南北向带状分布。"梅花"和"米雷"具有相似的湿层结构,但热力和动力结构很不相同,"米雷"结构明显不对称,风速较大区域主要在风暴中心东侧,风暴内垂直上升速度弱,而"梅花"结构典型,全风速分布较对称、眼壁清楚,具有明显的深厚暖心,中心附近温度比"米雷"高2℃左右,"梅花"中心附近具有强烈的上升气流,最强上升速度超过4 m/s。WRF模式10 m风场预报对"米雷"和"梅花"在浙江沿海海面风力有较好的参考性。模式对热带气旋的强度模拟误差和气旋自身结构差异可能是导致"米雷"站点大风漏报偏多,而"梅花"空报偏多的原因。

With operational WRF meso-scale model in Ningbo observatory, two tropical cyclones （TC Meari and Muifa） with north track along the Zhejiang coast are investigated by comparative analysis. Results show that the correlation coefficient between model QPF and the observation are 0. 617 and 0. 478 respectively for Meari and Muifa. Ranked TS scores show that model the has better performance on Meari than on Muifa due to higher FAR （ False Alarm Rate） for TC Mnifa. And the major forecast error distribution for QPF over 20mm locates in eastern Zhejiang Province especially along coast with south-north orien- tation. The two TCs have similar moist layer structure but differ a lot in thermal-dynamical structures. Meari has asymmetric structure with higher velocity in eastern flank of the storm and weak vertical motion inside the storm, while Muifa has classic symmetric structure with clear eye wall, deep warm core and strong vertical motion. Near surface wind field forecast by WRF model have good reference for coastal high wind forecast. The model bias for intensity and structure simulation might be the rea- son for higher false alarm rate for Mnifa and higher missing rate for Meari in high wind forecast.