Identification

Title

Mobile doppler radar observations of a tornado in a supercell near Bassett, Nebraska, on 5 June 1999. Part II: Tornado-vortex structure

Abstract

This is Part II of a paper detailing an analysis of high-resolution wind and reflectivity data collected by a mobile, W-band Doppler radar; the analysis depicts the near-surface life history of a tornado in a supercell in north-central Nebraska on 5 June 1999. The structure of the tornado vortex near the ground is described from a sequence of sector scans at 10-15-s intervals during much of the lifetime of the tornado. The formation of the tornado vortex near the ground is described in Part I. The wind and reflectivity features in the tornado evolved on timescales of 10 s or less. A time history of the azimuthally averaged azimuthal and radial wind profiles and the asymmetric components of the azimuthal and radial wind fields in the tornado were estimated by applying the ground-based velocity track display (GBVTD) technique to the Doppler wind data. If the magnitude of the asymmetric part of the radial wind component were indeed much less than that of the azimuthal wind component (a necessary requirement for application of the GBVTD technique), then the azimuthal wind field was dominated by quasi-stationary wavenumber-2 disturbances for most of the lifetime of the tornado. The radius of maximum wind (RMW) contracted as the tornado intensified and increased as the tornado dissipated. Shorter-timescale oscillations in azimuthal wind speed and RMW were found that could be manifestations of inertial oscillations. Evidence was also found that the tornado vortex was two-celled when it was most intense. During the "shrinking stage," the vortex remained relatively wide and intense, even though the condensation funnel had narrowed substantially.

Resource type

document

Resource locator

Unique resource identifier

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http://n2t.net/ark:/85065/d72r3sbg

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

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Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

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East bounding longitude

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Temporal reference

Temporal extent

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End position

Dataset reference date

date type

publication

effective date

2003-05-13T00:00:00Z

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Use constraints

Copyright 2003 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

Responsible organisations

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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

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pointOfContact

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