A Ventilation Index for Tropical Cyclones
Name
Tang-2012-A VENTILATION INDEX.pdf
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1.11 MB
Format
Adobe PDF
Checksum (MD5)
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Author(s)
Tang, Brian
Emanuel, Kerry Andrew
Date Issued
December 2012
Journal
Bulletin of the American Meteorological Society
Publisher
American Meteorological Society
Citation
Tang, Brian, and Kerry Emanuel. “A Ventilation Index for Tropical Cyclones.” Bulletin of the American Meteorological Society 93, no. 12 (December 2012): 1901-1912. © 2012 American Meteorological Society
Version
Final published version
Abstract
An important environmental control of both tropical cyclone intensity and genesis is vertical wind shear. One hypothesized pathway by which vertical shear affects tropical cyclones is midlevel ventilation—or the flux of low-entropy air into the center of the tropical cyclone. Based on a theoretical framework, a ventilation index is introduced that is equal to the environmental vertical wind shear multiplied by the nondimensional midlevel entropy deficit divided by the potential intensity. The ventilation index has a strong influence on tropical cyclone climatology. Tropical cyclogenesis preferentially occurs when and where the ventilation index is anomalously low. Both the ventilation index and the tropical cyclone's normalized intensity, or the intensity divided by the potential intensity, constrain the distribution of tropical cyclone intensification. The most rapidly intensifying storms are characterized by low ventilation indices and intermediate normalized intensities, while the most rapidly weakening storms are characterized by high ventilation indices and high normalized intensities. Since the ventilation index can be derived from large-scale fields, it can serve as a simple and useful metric for operational forecasts of tropical cyclones and diagnosis of model errors.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Massachusetts Institute of Technology. Program in Atmospheres, Oceans, and Climate
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1175/bams-d-11-00165.1
