A Meso-scale Low System with a Multi-scale Structure, Developed over the East Sea on 20 January 2017: Sensitivity Experiments

Abstract

To reveal the development mechanism of a multi-scale structure with a meso-scale low system that was developed over the East Sea on 20 January 2017, a series of sensitivity experiments on several forcing factors were conducted using the WRF (the Weather Research and Forecastin) model, in which physical processes of condensational heating and surface sensible and/or latent heat fluxes were switched on/off and the northern Korean mountain complex flattened. The main results of the sensitivity experiments indicated that while condensational heating is the most important physical process for the development of the meso-α-scale low (main low), surface heat flux (surface sensible heat flux and latent heat flux) is the most important process that lead to the development of the meso-β-scale low along the trough (shear zone). The important role of surface heat flux is reflected by the process, in which the low-level troposphere became stable when the surface heat flux was switched off, leading to a weakening of convective activity and relevant convergent flow along the trough. This resulted in a weak shear formation, leading to a restraint in the development of the meso-β-scale low in the trough.