Identification

Title

The microphysical structure and evolution of Hawaiian rainband clouds. Part 1. Radar observations of rainbands containing high reflectivity cores

Abstract

Radar reflectivity factors exceeding 60 dBZ are documented within shallow (<3 km), warm (>0°C), summertime tropical rainbands offshore of the island of Hawaii. Dual-Doppler radar measurements from the Hawaiian Rainband Project are used to document the formation, evolution, and kinematic structure of the high reflectivity cores. The authors show that extremely high radar reflectivities (50-60 dBZ) can develop from echo free regions (-20 dBZ) within approximately 15 min and are preceded by 5-9 m s⁻¹ peak updrafts. High reflectivities (>50 dBZ) typically first formed in the middle or upper part of the clouds. Over the next 10-15 min, the mature high reflectivity cores extended vertically through the cloud depth and then collapsed to the surface as the updrafts weakened. A near-upright orientation of most updrafts producing these high reflectivity cores is conceptually consistent with the idea that large raindrops grow in the highest liquid water content while falling through the updraft core. Strong outflows near the inversion led to the formation of sloped radar echo overhangs surrounding the cells. The bases of the overhangs descended to the surface with time, leading to an overall increase in the width of the rainbands. Short-lived downdrafts were present in the upper part of the clouds in mature and dissipating stages of cells' life cycles but were not observed in the lower parts of the cloud, even in intense precipitation shafts.

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document

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https://n2t.org/ark:/85065/d7pr7w0b

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eng

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geoscientificInformation

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publication

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2016-01-01T00:00:00Z

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publication

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1997-02-01T00:00:00Z

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Copyright 1997 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

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opensky@ucar.edu

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http://opensky.ucar.edu/

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