关键词: 持续性大雾, 垂直结构, 动力结构, 机制

Abstract:

Based on the conventional observation data and NCEP 1° × 1°reanalysis data，the circulation background，atmospheric stratification，dynamic and thermal struture for a sustained heavy fog from 12 to 16 January 2013 in central and western Shandong Province　were analyzed．The results showed that the straight westly air flow in middle and upper level，the warm temperature ridge at low level　of troposphere and the persistant surface cold high provided an appropriate condition for the sustained heavy fog weather event． The sustained fog event went through three phases including radiation fog，radiation－advection fog and advection fog，the thickness of moist layer and the intensity of temperature inversion were different in different phases of the fog event．The proper wind velocity and low level weak water vapor convergence were favourable to the fog weather．The low－level convergence ascending movement and middle high level divergence descending movement formed inversion layer at the interface，which was favorable to appearence of the thick fog，while the entire level convergence ascending movement was easy to form medium and high cloud，which wasn t favourable to vapour gathering，so there was no thick fog．

Key words:  
sustained heavy fog, vertical structure, dynamic structure, mechanisms analysis