Explosive Cyclogenesis around the Korean Peninsula in May 2016 from a Potential Vorticity Perspective: Case Study and Numerical Simulations

Ki-Young Heo,Taemin Ha,Kyung-Ja Ha

doi:10.3390/atmos10060322

Abstract

An explosive cyclone event that occurred near the Korean Peninsula in early May 2016 is simulated using the Weather Research and Forecasting (WRF) model to examine the developmental mechanisms of the explosive cyclone. After confirming that the WRF model reproduces the synoptic environments and main features of the event well, the favorable environmental conditions for the rapid development of the cyclone are analyzed, and the explosive development mechanisms of the cyclone are investigated with perturbation potential vorticity (PV) fields. The piecewise PV inversion method is used to identify the dynamically relevant meteorological fields associated with each perturbation PV anomaly. The rapid deepening of the surface cyclone was influenced by both adiabatic (an upper tropospheric PV anomaly) and diabatic (a low-level PV anomaly associated with condensational heating) processes, while the baroclinic processes in the lower troposphere had the smallest contribution. In the explosive phase of the cyclone life cycle, the diabatically generated PV anomalies associated with condensational heating induced by the ascending air in the warm conveyor belt are the most important factors for the initial intensity of the cyclone. The upper-level forcing is the most important factor in the evolution of the cyclone’s track, but it is of secondary importance for the initial strong deepening.

Highlights

Explosive cyclones are extratropical cyclones characterized by a strong deepening and are often linked to extreme weather conditions, including strong winds and heavy rainfall, and to extreme ocean events such as abnormally high waves [2] and, in some cases, storm surge
The RUP cyclone continued to deepen with a small deepening rate throughout the 48-h simulation, the initial central sea level pressure (CSLP) was smaller than that of the RMP cyclone
The RMP simulation is similar in deepening rate to the control (CTL) simulation during a +27-h integration (Figure 8b), but it has a weak cyclone because the highest initial CSLP is 1019 hPa

Summary

Introduction

Explosive cyclones are extratropical cyclones characterized by a strong deepening (a sea level pressure decrease larger than 24 hPa within 24 h at 60◦ N or the equivalent [1]) and are often linked to extreme weather conditions, including strong winds and heavy rainfall, and to extreme ocean events such as abnormally high waves [2] and, in some cases, storm surge. According to Shapiro et al [11], explosive cyclones initially develop in response to a combination of different mechanisms that include upper-level cyclonic vorticity advection, low-level warm air advection, and latent heat release. This may be influenced by Rossby wave breaking, which contributes to the development of intense cyclones by constraining and intensifying the upper-level jet stream [12,13,14]. The heating and moistening of the atmosphere and the reduced stability due to air–sea interactions are important prior to and during explosive cyclone development [15,16,17].

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