Structure of a Low-Level Jet and it's Role in Triggering and Organizing Moist Convection over Taiwan: A TAMEX Case Study


This paper presents the kinematic and thermodynamic structure of a severe precipitating convective line associated with a low level jet (LLJ) observed during Taiwan Area Mesoscale EXperiment (TAMEX) on 24 - 25 June 1987. The meso- and convective-scale features of the Mei-Yu front and the associated quasi-stationary mesoscale convective systems that lead to heavy precipitation are described. The mesoscale structure of the LLJ and its relationship with the moist convection are emphasized.
The major convective precipitation associated with the convective line occurred at the pre-frontal region. At the post-frontal region, no organized reflectivity pattern existed. Accompanying the quasi-stationary convective line, a southwesterly LLJ of 20 ms-1 at 1 km existed. The LLJ decelerated when approaching the major convective precipitating areas and showed a distinct diffluent pattern . This flow structure produced concentrated, enhanced warm and moist air convergence which favored new convec­tative cell information. The strength of the deflection of the LLJ depends on the intensity of the convective downward motion associated with the mesoscale convective system.

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