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Effects of Synoptic-Scale Control on Long-Term Declining Trends of Summer Fog Frequency over the Pacific Side of Hokkaido Island

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Please use this identifier to cite or link to this item:http://hdl.handle.net/2115/55189

Title: Effects of Synoptic-Scale Control on Long-Term Declining Trends of Summer Fog Frequency over the Pacific Side of Hokkaido Island
Authors: Sugimoto, Shiori Browse this author
Sato, Tomonori Browse this author →KAKEN DB
Nakamura, Kazuki Browse this author
Keywords: Synoptic climatology
Fog
Synoptic-scale processes
Climate variability
Issue Date: Oct-2013
Publisher: American Meteorological Society
Journal Title: Journal of Applied Meteorology and Climatology
Volume: 52
Issue: 10
Start Page: 2226
End Page: 2242
Publisher DOI: 10.1175/JAMC-D-12-0192.1
Abstract: In this study, long-term visibility data for the Pacific Ocean side of Hokkaido Island, northeast Japan, are investigated to clarify the relationship between interannual variation in summer fog frequency (FF) and large-scale circulation patterns. At Kushiro, a significant FF decrease is found during 1931-2010 even without the influence of the observatory's relocation after 2000. In particular, since the late 1970s, a linear declining trend has accelerated, as evidenced by an increased number of years with very low FF in July and August. To clarify the climatological factor causing the summer FF declining trend at Kushiro, atmospheric vertical conditions in the planetary boundary layer and large-scale circulation are examined during 1989-2009 and 1958-2002, respectively, using available datasets. Composite analyses that are based on radiosonde observations reveal that the shallow fog layer is covered with a strong inversion layer during fog days whereas the inversion layer is absent during nonfog days. Composite circulation anomalies for the low-FF years at Kushiro show an intensified Okhotsk high (OH) pressure feature and southward shrinking of the North Pacific high (NPH) in July, in addition to the eastward displacement or shrinking of the NPH in August. These anomalous synoptic circulation patterns cause weakening in the southerly-southeasterly wind, which reduces sea-fog advection toward Kushiro and prevents the formation of stable stratification over the sea-fog layer. The authors suggest that the interannual variation in summer FF with the recent accelerated decline at Kushiro is primarily controlled by changes in the synoptic circulation associated with the OH and NPH development.
Rights: © Copyright 2013 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 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 copyright@ametsoc.org.
Type: article
URI: http://hdl.handle.net/2115/55189
Appears in Collections:環境科学院・地球環境科学研究院 (Graduate School of Environmental Science / Faculty of Environmental Earth Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 杉本 志織

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