着氷性降水の気候学的特徴と地域性について  [in Japanese] Climatological characteristics and local influences on occurrence of freezing precipitation in Japan  [in Japanese]

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Abstract

過去14冬季間(1989年11月~2003年5月)における気象庁の地上気象観測資料から,着氷性の雨,着氷性の霧雨,凍雨の発生に関する地域分布と,季節変化および経年変化を調べた.日本では,これらの降水種は1月から3月の時期に発生することが多く,毎年10回程度の割合で観測されている.このうち着氷性の雨の発生率は毎年数回程度で,12月~1月に発生する場合が多い.<BR>着氷性の雨と凍雨の発生率が高いのは,中部地方以北の内陸山間部と関東地方以北の太平洋側平野部である.この両地域に着目して,着氷性の雨や凍雨が発生するときの気象条件の形成過程を調べたところ,地上付近の寒気層の形成は,局地的な気象現象や地形の影響を強く受けることがわかった.内陸山間部では盆地地形による冷気湖の形成が関与しており,太平洋側平野部では内陸からの寒気流出によって地上付近の寒気層が形成される.一方,上空暖気層の形成は,総観規模の気圧配置に伴う暖気移流に起因する.

We have examined geographical distributions, and seasonal and annual variations, of occurrences of freezing precipitation (rain and drizzle) and ice pellets, by using Japan Meteorological Agency surface meteorological data for the past 14 winter seasons (November 1989-May 2003). In Japan, these precipitation types have often occurred for the period January to March, and are observed about ten times every winter. Freezing rain falls only a few times each season, mostly from December to January.<BR>Most of the freezing rain and ice pellets occur in the inland ravines in the northern Chubu region, and in plains on the Pacific Ocean side of northern Kanto. The atmospheric condition when the freezing rain and ice pellets were observed in both regions was examined. As a result, it was found that local meteorology and geographical features strongly influence the formation of the cold air layer in which descending raindrops become supercooled in the vicinity of the ground. In inland ravines, a cold air reservoir within each basin plays an important role in the formation of the cold air layer near the ground. In the plains on Pacific Ocean side, in contrast, cold air drainage from inland peculiar to these plains contributed to forming the cold air layer. In addition, advected warm air layer melts snowflakes associated with the synoptic low-pressure system above the cold air layers providing the conditions required for freezing rain or ice pellets to occur.

Journal

  • Journal of the Japanese Society of Snow and Ice

    Journal of the Japanese Society of Snow and Ice 66(5), 541-552, 2004-09-15

    The Japanese Society of Snow and Ice

References:  28

Cited by:  1

Codes

  • NII Article ID (NAID)
    10013540743
  • NII NACSIS-CAT ID (NCID)
    AN00131221
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    03731006
  • NDL Article ID
    7093664
  • NDL Source Classification
    ZM43(科学技術--地球科学--気象)
  • NDL Call No.
    Z15-23
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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