Identification

Title

The formation of moist vortices and tropical cyclones in idealized simulations

Abstract

The upscale aggregation of convection is used to understand the emergence of rotating, coherent midtropospheric structures and the subsequent process of tropical cyclone formation. The Cloud Model, version 1 (CM1), is integrated on an f plane with uniform sea surface temperature (SST) and prescribed uniform background flow. Deep convection is maintained by surface fluxes from an ocean with uniform surface temperature. Convection begins to organize simultaneously into moist and dry midtropospheric patches after 10 days. After 20 days, the patches begin to rotate on relatively small scales. Moist cyclonic vortices merge, eventually forming a single dominant vortex that subsequently forms a tropical cyclone on a realistic time scale of about 5 days. Radiation that interacts with clouds and water vapor aids in forming coherent rotating structures. Using the path to genesis provided by the aggregated solution, the relationship between thermodynamic changes within the vortex and changes in the character of convection prior to genesis is explored. Consistent with previous studies, the approach to saturation within the midtropospheric vortex accelerates the genesis process. A novel result is that, prior to genesis, downdrafts become widespread and somewhat stronger. The increased downdraft mass flux leads to stronger and larger surface cold pools. Shear-cold pool dynamics promote the organization of lower-tropospheric updrafts that spin up the surface vortex. It is inferred that the observed inconsistency between convective intensity and thermodynamic stabilization prior to genesis results from sampling limitations of the observations wherein the important cold pool gradients are unresolved.

Resource type

document

Resource locator

Unique resource identifier

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http://n2t.net/ark:/85065/d7qv3nqp

codeSpace

Dataset language

eng

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geoscientificInformation

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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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publication

effective date

2015-09-01T00:00:00Z

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Copyright 2015 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.

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None

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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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