Influence of the Thermal Structure on the Intensification of the Extreme Arctic Cyclone in August 2016

Abstract

AbstractAs one of the most dangerous weather systems affecting the Arctic region, Arctic cyclones (ACs) significantly affect Arctic shipping routes and navigation safety. This study investigates the evolution and structure characteristics of an extreme AC in August 2016 (AC16) based on the Arctic System Reanalysis version 2 (ASRv2) data set. The key factors affecting the development of AC16 are revealed by diagnosing the pressure tendency equation (PTE), with focus on the influence of thermal structure during two rapid intensification stages. It is found that PTE‐diagnosed results can well reproduce the evolution of AC16. The air‐column virtual temperature change is the decisive contributor decreasing the surface pressure and thus intensifying AC16, while the change in geopotential at upper boundary and the mass change caused by evaporation and precipitation have less effect. Further analysis indicates that at the initial rapid intensification stage, the middle‐lower‐level diabatic heating probably related to condensation latent heat and the upper‐level warm advection influenced by tropopause polar vortices (TPVs) have crucial effects on the air‐column warming, which leads to the AC16 rapid intensification initially. At the secondary rapid intensification stage, the upper‐level warm advection affected by TPVs further increases the air‐column virtual temperature, which is the dominant contributor to the AC16 secondary drastic intensification.