Potential vorticity mixing and rapid intensification in the numerically simulated supertyphoon haiyan (2013)
Journal
Journal of the Atmospheric Sciences
Journal Volume
77
Journal Issue
6
Pages
2067-2090
Date Issued
2020
Author(s)
Tsujino, S.
Abstract
The inner-core dynamics of Supertyphoon Haiyan (2013) undergoing rapid intensification (RI) are studied with a 2-km-resolution cloud-resolving model simulation. The potential vorticity (PV) field in the simulated storm reveals an elliptical and polygonal-shaped eyewall at the low and middle levels during RI onset. The PV budget analysis confirms the importance of PV mixing at this stage, that is, the asymmetric transport of diabatically generatedPVto the stormcenter fromthe eyewall and the ejection of PVfilaments outside the eyewall. We employ a piecewise PV inversion (PPVI) and an omega equation to interpret the model results in balanced dynamics. The omega equation diagnosis suggests eye dynamical warming is associated with the PV mixing. The PPVI indicates that PVmixing accounts for about 50% of the central pressure fall during RI onset. The decrease of central pressure enhances the boundary layer (BL) inflow. The BL inflow leads to contraction of the radius of the maximum tangential wind (RMW) and the formation of a symmetric convective PV tower inside the RMW. The eye in the later stage of the RI is warmed by the subsidence associated with the convective PV towers. The results suggest that the pressure change associated with PV mixing, the increase of the symmetric BL radial inflow, and the development of a symmetric convective PV tower are the essential collaborating dynamics for RI. An experiment with 500-m resolution shows that the convergence of BL inflow can lead to an updraft magnitude of 20ms-1and to a convective PVtower with a peak value of 200 PVU (1 PVU = 10-6K kg-1m2s-1). © 2020 American Meteorological Society. All rights reserved.
SDGs
Other Subjects
Boundary layers; Budget control; Storms; Vorticity; Asymmetric transport; Cloud-resolving model simulations; Potential vorticity; Potential vorticity mixing; Pressure change; Rapid intensification; Simulated storms; Tangential wind; Mixing; atmospheric convection; climate modeling; mesoscale meteorology; numerical model; potential vorticity; storm surge; Typhoon Haiyan 2013
Type
journal article