Development Processes of the East Asian Cyclones over the Korean Peninsula

Abstract. The development processes of the extratropical cyclones passing the Korean Peninsula during the period of 1979–2017 are quantitatively evaluated in the potential vorticity (PV) perspective. A feature tracking algorithm is applied to the ERA-Interim reanalysis data to objectively identify the distinct northern- and southern-track (NT and ST) cyclones affecting the region in the cold season. The dynamic and thermodynamic contributions to the development of these two categories of cyclones are then comparatively assessed in terms of the relative vorticity tendency resulting from the PV tendency inversion. It is quantified through inversion that the NT cyclones develop 87.9 % dynamically and 6.2 % thermodynamically. In contrast, the respective contributions to the ST cyclones are 71.8 % and 43.5 % for the ST cyclones, with negative effects from non-explicit processes. In both NT and ST cyclones, the zonal PV advection in the upper troposphere is the most influential for the dynamic development, while nonlinear advection being more important in the former. The larger thermodynamic contribution of the latter is attributed to more latent heating being involved in the development, which produces more lower-level PV and reduces damping from vertical PV advection. These results indicate that East Asian cyclones passing the Korean Peninsula have different development processes depending on their tracks.