Identification

Title

The role of turbulence in an intense Tropical Cyclone: Momentum diffusion, eddy viscosities, and mixing lengths

Abstract

Improved representation of turbulent processes in numerical models of tropical cyclones (TCs) is expected to improve intensity forecasts. To this end, the authors use a large-eddy simulation (with 31-m horizontal grid spacing) of an idealized category 5 TC to understand the role of turbulent processes in the inner core of TCs and their role on the mean intensity. Azimuthally and temporally averaged budgets of the momentum fi elds show that TC turbulence acts to weaken the maximum tangential velocity, diminish the strength of radial inflow fl ow into the eye, and suppress the magnitude of the mean eye- wall updraft. Turbulent fl ux divergences in both the vertical and radial directions are shown to influence fl uence the TC mean wind fi eld, with the vertical being dominant in most of the inflowing fl owing boundary layer and the eyewall (analogous to traditional atmospheric boundary layer fl ows), while the radial becomes important only in the eyewall. The validity of the downgradient eddy viscosity hypothesis is largely confirmed fi rmed for mean velocity fi elds, except in narrow regions which generally correspond to weak gradients of the mean fi elds, as well as a narrow region in the eye. This study also provides guidance for values of effective eddy viscosities and vertical mixing length in the most turbulent regions of intense TCs, which have rarely been measured observationally. A generalized formulation of effective eddy viscosity (including the Reynolds normal stresses) is presented.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7cj8jq4

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2024-08-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

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name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact