Combined Effects of Midlevel Dry Air and Vertical Wind Shear on Tropical Cyclone Development. Part II: Radial Ventilation

This study demonstrates how midlevel dry air and vertical wind shear (VWS) can modulate tropical cyclone (TC) development via radial ventilation. A suite of experiments was conducted with different combinations of initial midlevel moisture and VWS environments. Two radial ventilation structures are...

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Bibliographic Details
Published in:Journal of the atmospheric sciences Vol. 78; no. 3; pp. 783 - 796
Main Authors: Alland, Joshua J., Tang, Brian H., Corbosiero, Kristen L., Bryan, George H.
Format: Journal Article
Language:English
Published: Boston American Meteorological Society 01.03.2021
Subjects:
Aerodynamics
Air
Air temperature
Convection
Cyclone development
Cyclones
Downdraft
Dry air
Equivalence
Equivalent potential temperature
Hurricanes
Mass flux
Outflow
Potential temperature
Relative humidity
Storms
Stunting
Transport
Tropical climate
Tropical cyclone development
Tropical cyclones
Ventilation
Vertical wind shear
Wind
Wind shear
ISSN:0022-4928, 1520-0469
Online Access:Get full text
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Summary:This study demonstrates how midlevel dry air and vertical wind shear (VWS) can modulate tropical cyclone (TC) development via radial ventilation. A suite of experiments was conducted with different combinations of initial midlevel moisture and VWS environments. Two radial ventilation structures are documented. The first structure is positioned in a similar region as rainband activity and downdraft ventilation (documented in Part I) between heights of 0 and 3 km. Parcels associated with this first structure transport low–equivalent potential temperature air inward and downward left of shear and upshear to suppress convection. The second structure is associated with the vertical tilt of the vortex and storm-relative flow between heights of 5 and 9 km. Parcels associated with this second structure transport low–relative humidity air inward upshear and right of shear to suppress convection. Altogether, the modulating effects of radial ventilation on TC development are the inward transport of low–equivalent potential temperature air, as well as low-level radial outflow upshear, which aid in reducing the areal extent of strong upward motions, thereby reducing the vertical mass flux in the inner core, and stunting TC development.
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ISSN:0022-4928
1520-0469
DOI:10.1175/JAS-D-20-0055.1