Identification

Title

The role of low-level flow direction on tropical cyclone intensity changes in a moderate-sheared environment

Abstract

The impact of low-level flow (LLF) direction on the intensification of intense tropical cyclones under moderate deep-layer shear is investigated based on idealized numerical experiments. The background flow profiles are constructed by varying the LLF direction with the same moderate deep-layer shear. When the maximum surface wind speed of the simulation without background flow reaches 70 kt (36 m s(-1)), the background flow profiles are imposed. After a weakening period in the first 12 h, the members with upshear-left-pointing LLF (fast-intensifying group) intensify faster between 12 and 24 h than those members (slow-intensifying group) with downshear-right-pointing LLF. The fast-intensifying group experiences earlier development of inner-core structures after 12 h, such as potential vorticity below the midtroposphere, upper-level warm core, eyewall axisymmetrization, and radial moist entropy gradient, while the inner-core features of the slow-intensifying group remain relatively weak and asymmetric. The FI group experiences smaller tilt increase and stronger midlevel PV ring development. The upshear-left convection during 6-12 h is responsible for the earlier development of the inner core by reducing ventilation, providing axisymmetric heating, and benefiting the eyewall development. The LLF of the fast-intensifying group enhances surface heat fluxes in the downshear side, resulting in higher energy supply to the upshear-left convection from the boundary layer. In all, this study provides new insights on the impact of LLF direction on intense storms under moderate shear by modulating the surface heat fluxes and eyewall convection.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7k35z72

codeSpace

Dataset language

eng

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Topic category

geoscientificInformation

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keyword value

Text

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title

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reference date

date type

publication

effective date

2016-01-01T00:00:00Z

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East bounding longitude

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date type

publication

effective date

2021-09-01T00:00:00Z

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Conformity

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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

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