High-Resolution Simulation and Analysis of the Mature Structure of a Polar Low over the Sea of Japan on 21 January 1997
This paper presents a high-resolution simulation of a remarkable polar low observed over the Sea of Japan on 21 January 1997 by using a 5-km mesh non-hydrostatic model MRI-NHM (Meteorological Research Institute Non-Hydrostatic Model). A 24-hour simulation starting from 0000 UTC 21 January 1997 successfully reproduced the observed features of the polar low such as the wrapping of western part of an initial E W orientation vortex, the spiral-shaped bands, the cloud-free "eye", and the warm core structure at its mature stage. The "eye" of the simulated polar low was relatively dry, and was associated with a strong downdraft. A thermodynamic budget analysis indicates that the "warm core" in the "eye"region was mainly caused by the adiabatic warming associated with the downdraft. The relationship among the condensational diabatic heating, the vertical velocity, the convergence of the moisture flux, and the circulation averaged within a 50 km×50 km square area around the polar low center shows that they form a positive feedback loop, and this loop is not inconsistent with the CISK (Conditional Instability of the Second Kind) mechanism during the developing stage of the polar low.
作 者： 傅刚 郭敬天 张美根 作者单位： 傅刚(Department of Marine Meteorology, Ocean University of China, Qingdao 266003;Laboratory of Physical Oceanography, Ocean University of China, Qingdao 266003;State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry,Institute of At)郭敬天(Department of Marine Meteorology, Ocean University of China, Qingdao 266003)
张美根(State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry,Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029)
刊 名： 大气科学进展(英文版) ISTIC SCI 英文刊名： ADVANCES IN ATMOSPHERIC SCIENCES 年，卷(期)： 2004 21(4) 分类号： 关键词： polar low Sea of Japan high-resolution simulation warm core structure