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Microphysical Properties of Slow-Falling and Fast-Falling Ice Pellets Formed by Freezing Associated with Evaporative Cooling

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Please use this identifier to cite or link to this item:http://hdl.handle.net/2115/61990

Title: Microphysical Properties of Slow-Falling and Fast-Falling Ice Pellets Formed by Freezing Associated with Evaporative Cooling
Authors: Nagumo, Nobuhiro Browse this author
Fujiyoshi, Yasushi Browse this author →KAKEN DB
Keywords: Physical Meteorology and Climatology
Freezing precipitation
Issue Date: Nov-2015
Publisher: American Meteorological Society
Journal Title: Monthly weather review
Volume: 143
Issue: 11
Start Page: 4376
End Page: 4392
Publisher DOI: 10.1175/MWR-D-15-0054.1
Abstract: This paper describes a numerical and observational study focused on ice-pellet formation and microphysical properties near 0 degrees C from an ice-pellet-dominated storm associated with an unusually warm and dry atmosphere on 10 April 2005, in Sapporo, Japan. A one-dimensional numerical model simulation indicated that precipitation particle temperatures were sensitive to environmental temperature and relative humidity and close to the wet-bulb temperature. The simulation demonstrated that completely melted snowflakes could refreeze by evaporative cooling. Moreover, initial freezing could be explained by contact ice nucleation at the height of the minimum wet-bulb temperature.Observations using a 2D video distrometer (2DVD) indicated that ice pellets exhibited two modes of fall velocities at surface temperatures near 0 degrees C during the same time period: slow falling and fast falling. The slow-falling ice pellets exhibited a velocity similar to the average terminal velocity of hail, whereas the velocities of the fast-falling ice pellets were closer to those of raindrops. Surface roundness and fracturing characteristics of ice pellets suggest that slow-falling ice pellets froze rapidly and uniformly in a relatively cold dry layer with a wet-bulb temperature near -4 degrees C. In contrast, the fast-falling ice pellets exhibited the properties of ice particles with a wet smooth surface, suggesting that they froze slowly in a relatively warm layer by contacting ice crystals or splinters generated by preceding slow-falling ice pellets.
Rights: © Copyright November 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 of the U.S. Copyright Act September 2010 Page 2 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a web site or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS Copyright Policy, available on the AMS Web site located at (http://www.ametsoc.org/) or from the AMS at 617-227-2425 or copyrights@ametsoc.org.
Type: article
URI: http://hdl.handle.net/2115/61990
Appears in Collections:低温科学研究所 (Institute of Low Temperature Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 藤吉 康志

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