The Behavior of Moist Potential Vorticity in the Interactions of Binary Typhoons Lekima and Krosa (2019) in with Different High-Resolution Simulations

The binary typhoon systems of Lekima and Krosa (2019) have been simulated using the Weather Research and Forecast (WRF) model with 27 km, 9 km, and 3 km resolutions and their behaviors of moist potential vorticity (MPV) in these simulations have been analyzed. All the simulations clearly show that the main sources of instability energy include two parts of MPV—the convective energy from the environmental field (MPV1) and the internal transferring energy between the binary typhoons (MPV2). While typhoons absorb the convective energy from the upper ocean through vortex effects on their periphery as the main external MPV sources, there is an MPV conveying belt at the middle-low layer of the atmosphere in the binary typhoon system, transferring energy between binary typhoons and causing atmospheric baroclinicity changes. While all three-resolution simulations show the fundamental features of MPV and its transferring in the binary typhoon system, the 3 km resolution cloud-resolving simulation yield more detailed and accurate MPV structures inside the individual typhoon, which may have non-negligible feedbacks on the background. Based on the comprehensive characteristics of MPV in binary typhoon interactions, further understanding of the interactions of internal detailed structures inside typhoons and their feedbacks on the background may provide a theoretical basis for improving the forecast of typhoon intensity and track.