热带气旋低层水平流场的平面动力系统分析

ANALYSIS OF THE PLANE DYNAMIC SYSTEM OF LOW-LEVEL STREAMLINE FIELD OF TROPICAL CYCLONE

利用中国气象局上海台风研究所整理的热带气旋最佳路径资料,热带气旋云图、气象雷达回波图资料,ECMWF ERA-Interim再分析风场资料;并用大气运动方程和天气学原理分析得到热带气旋低层水平流场结构,根据流场建立平面非线性自治动力系统。结果表明,TC在成熟阶段或发展很强时期,由两组二维驻定微分方程组解确定水平流场,TC眼区以内气流沿顺时针方向流动,TC眼区以外气流沿逆时针方向流动。TC眼区内外相反方向风场之间为风向切变圆环,圆环上不断有气旋形成,并存在低空急流,是狂风暴雨出现区域。结论与合成雷达回波观测结果一致。

Based on the CMA-STI tropical cyclone best track data, cloud atlas data, weather radar echo data and the reanalysis of wind field data by ECMWF ERA-Interim, and with the atmospheric motion equations and synoptic principle, we analyzed the structure of the low-level horizontal flow field of tropical cyclone （TC）, and established a plane nonlinear autonomous dynamic system according to the flow field. The results show that the horizontal flow is determined by two groups of two-dimensional stationary differential equations when the TC is in the mature stage of development or a strong period; the air flows clockwise within the eye area but counterclockwise outside it. Between the wind fields of opposite direction that are inside and outside the eye zone there is a wind shear ring on which cyclones are formed consecutively, and there is a low-level jet where rough weather appears. The results are consistent with the observation by synthetic radar echoes.