2016年10月11-19日东南太平洋一次温带气旋过程分析

利用美国国家环境预报中心发布的FNL资料、红外卫星云图资料和船测资料,对2016年10月17-19日某船舶在东南太平洋遭遇的一次温带气旋过程进行研究,以此为大洋航线上温带气旋预报保障能力提高积累经验。结果表明:(1)温带气旋A由绕极槽北伸切断发展而来,自西向东移动过程中在南太平洋大洋中部与另一气旋B合并加强对船舶航行造成影响;(2)气旋A初生阶段,大气低层旋转程度较强;成熟发展阶段在近地面、大气上层旋转程度较强;当气旋B初生发展时,气旋A中心附近自500 hPa以下为绝对涡度小值区,其上为绝对涡度大值区,绝对涡度垂直轴线向近B一侧倾斜;(3)槽后及气旋中心附近正涡度平流与槽前随高度增强的暖平流共同促使气旋发展。

Analysis of an extratropical cyclone over the Southeast Pacific in 11-19 Oct 2016

The characteristic of an extratropical cyclone named A over the Southeast Pacific in 11-19 Oct 2016 is investigated using NCEP FNL data,HIMAWARI and GOES infrared satellite imagery.It is found that cyclone A developed from the polar trough and moved eastward.It merged with another cyclone named B in the middle of the south Pacific and affected the navigation of ships.A relatively high degree of rotation had been found in the lower atmosphere during the initial phase of cyclone A,while the rotation was stronger both at the lower and upper atmosphere in its mature phase.When cyclone B was developed,the absolute vorticity of cyclone A was small below 500 hPa and large above 500 hPa,and the vertical axis of absolute vorticity was inclined to cyclone B.The factors,which dominated the cyclonic development including the warm advection increased with altitude,and the positive vorticity advection after the trough and near the center of the cyclone.