Physical understanding of the tropical cyclone wind-pressure relationship. Issue 1 (December 2017)

• Record Type: Journal Article
• Authors: Chavas, Daniel; Reed, Kevin; Knaff, John
• Is Part Of: Nature communications. Volume 8:Issue 1(2017)
• Page Start: 1
• Page End: 11
• Publication Date: 2017-12
• Subjects: Biology -- Periodicals; Physical sciences -- Periodicals; 505
• DOI: 10.1038/s41467-017-01546-9
• Languages: English
• ISSNs: 2041-1723

Abstract

Abstract The relationship between the two common measures of tropical cyclone intensity, the central pressure deficit and the peak near-surface wind speed, is a long-standing problem in tropical meteorology that has been approximated empirically yet lacks physical understanding. Here we provide theoretical grounding for this relationship. We first demonstrate that the central pressure deficit is highly predictable from the low-level wind field via gradient wind balance. We then show that this relationship reduces to a dependence on two velocity scales: the maximum azimuthal-mean azimuthal wind speed and half the product of the Coriolis parameter and outer storm size. This simple theory is found to hold across a hierarchy of models spanning reduced-complexity and Earth-like global simulations and observations. Thus, the central pressure deficit is an intensity measure that combines maximum wind speed, storm size, and background rotation rate. This work has significant implications for both fundamental understanding and risk analysis, including why the central pressure better explains historical economic damages than does maximum wind speed. Tropical cyclone intensity is commonly measured by both central pressure and maximum wind speed, yet the physical relationship between the two is not understood. Here the authors show that the central pressure is an intensity measure that depends on maximum wind speed and the product of storm size and background rotation rate.