Identification

Title

Airborne measurement of liquid and total water content

Abstract

Two identical liquid water content (LWC) King probes--one total water content/liquid water content (TWC/LWC) Nevzorov probe and two constant-temperature T probes that are different in size to distinguish particles of different densities and diameters (section 2c)--were flown during the Alliance Icing Research Study (AIRS) II field campaign in the fall of 2003. This paper assesses measurements performed during several flights in mostly stratiform clouds. The two LWC King probes tracked well; however, discrepancies of up to 0.1 g m⁻³ for 1-s LWC measurements of 0.3 g m⁻³ were observed. Agreement between probes of different geometry and size was generally favorable, while levels of disagreement between the probes changed during numerous cloud penetrations from less than 20% up to a factor of 2, varying with flight conditions and microphysical structure of the cloud. Disagreement between probes was even larger when detecting ice water content (IWC). Measurement differences were attributed to different collection efficiencies resulting from preferred particle size, shape, and density and local aerodynamic effects around the aircraft. Measurements from a single probe are subject to uncertainty at a single point in time beyond the noise and drift level of the instrument. This uncertainty is evaluated considering particle habit, diameter, and density, and probe geometry and size, in addition to particle impact, breakup/splash, and bounce. From a working point of view, the intercomparison of several probes is subject to real but unknown spatial differences because of different locations between air samples. Comparison of identical probes is not appropriate because each measurement in itself is unique by definition. Thus, instead of duplication of instruments, subject to these levels of agreement, the use of a single probe is a practical approach while remaining aware of its limitations and capabilities.

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document

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http://n2t.net/ark:/85065/d7125tdb

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eng

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geoscientificInformation

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reference date

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publication

effective date

2016-01-01T00:00:00Z

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publication

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2011-09-01T00:00:00Z

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Copyright 2011 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

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UCAR/NCAR - Library

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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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