Successive Development of Two Types of Vortex Disturbance over the Japan Sea in Winter(Numerical Simulation).

Abstract

Two types of vortex disturbance over the Japan Sea in winter are well simulated in the case of 23-24 January 1990, with a high-resolution (6.0km grid at 36° N) one-way triple-nested hydrostatic numerical weather prediction model. They take different tracks with a very short interval. One is generated over the Continent of Asia and advances toward the east-northeast over the Japan Sea. Its vorticity center is found at a middle layer (650-700hPa) at first, and then shifts slowly down to a lower layer (∼950hPa). It has a multi-scale structure in which a meso-β-scale vortex is embedded in a meso-α-scale one. The other type of disturbance is originally generated over the northwestern part of the Japan Sea and advances toward the southeast along the topographically-induced horizontal shear line associated with the Japan-Sea Polar-airmass Convergence Zone (JPCZ) in the lower layer. The disturbance consists of several meso-β-scale vortices in line with their vorticity maxima in the lower layer. These characteristics of each disturbance are related to its own synoptic conditions, the key features of which are summarized in a scenario of evolution of the vortex disturbances.