Identification

Title

Tropical oceanic hot towers: Need they be undilute to Transport Energy from the Boundary Layer to the Upper Troposphere Effectively? An Answer Based on Trajectory Analysis of a simulation of a TOGA COARE convective system

Abstract

This paper addresses questions resulting from the authors' earlier simulation of the 9 February 1993 Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Research Experiment (TOGA COARE) squall line, which used updraft trajectories to illustrate how updrafts deposit significant moist static energy (in terms of equivalent potential temperature θe) in the upper troposphere, despite dilution and a θe minimum in the midtroposphere. The major conclusion drawn from this earlier work was that the "hot towers" that Riehl and Malkus showed as necessary to maintain the Hadley circulation need not be undilute. It was not possible, however, to document how the energy (or θe) increased above the midtroposphere. To address this relevant scientific question, a high-resolution (300 m) simulation was carried out using a standard 3-ICE microphysics scheme (Lin-Farley-Orville). Detailed along-trajectory information also allows more accurate examination of the forces affecting each parcel’s vertical velocity W, their displacement, and the processes impacting θe, with focus on parcels reaching the upper troposphere. Below 1 km, pressure gradient acceleration forces parcels upward against negative buoyancy acceleration associated with the sum of (positive) virtual temperature excess and (negative) condensate loading. Above 1 km, the situation reverses, with the buoyancy (and thermal buoyancy) acceleration becoming positive and nearly balancing a negative pressure gradient acceleration, slightly larger in magnitude, leading to a W minimum at midlevels. The W maximum above 8 km and concomitant θe increase between 6 and 8 km are both due to release of latent heat resulting from the enthalpy of freezing of raindrops and riming onto graupel from 5 to 6.5 km and water vapor deposition onto small ice crystals and graupel pellets above that, between 7 and 10 km.

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document

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http://n2t.net/ark:/85065/d70c4wgg

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Dataset language

eng

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geoscientificInformation

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title

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publication

effective date

2016-01-01T00:00:00Z

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publication

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2012-01-01T00:00:00Z

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Copyright 2012 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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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/

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