冬季西南日本太平洋側に発生する雲バンドと地上気象要素分布の関係
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概要
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In his preceding paper (NiSHINA 1984), the author discussed an orographic effect onthe cloud distribution in the Central Japan under the winter monsoon situation. Such anorographic effect is considered to exist also in the Southwest Japan in winter. The purposeof this study is to examine the relation between the location of the band clouds onthe Pacific Ocean side in the Southwest Japan and the distribution of surface meteorologicalelements, and to discuss an orographic effect on the distribution of these band clouds in thisregion.<BR>In this study, the author used GMS sector visible pictures at 00 GMT on the all daysin three winters (December, January and February) from December in 1978 to Februaryin 1981. Of these all pictures, the pictures of the 42 days on which appeared at least fourlines of band clouds of six as shown in Fig. 2 were analyzed. In my preceding paper, theresult was obtained that the generation of local anticyclones and cyclones differs under dif-ferent wind direction at 800-850mb altitude. According to this result, the 42 days wereclassified into four types (W, WNW, NW, NNW) by the wind direction at 850mb altitudein Shionom isaki. Meteorological elements at 850mb altitude and at the surface were analyzedin each type.<BR>The results are summarized as follows:<BR>1. The band clouds in the leeward of the Kii Mts., the Shikoku Mts., or the Kyushu Mts. all appear from the low pressure region in the leeward of these mountains. But theappearance rate of these band clouds differs under different upper (850mb level) wind direc-tion, which can be explained by the relation between the upper wind direction and the direction of these mountains.<BR>2. The band cloud from the Kii Strait appears along the line of discontinuity of windextending from the low pressure region in the leeward of the Chugoku Mts. when northnorth westerlyupper wind blows. Under westerly wind, it does on the outburst of the windfrom the Kanmon Strait through the Seto Inland Sea. But in the latter case, no bandcloud appears when high pressure region expands strongly from the Shikoku Mts. to theKii Mts.<BR>3. The outburst of the wind from the Kanmon Strait plays basically an importantrole in the appearance of the band cloud from the Bungo Strait. Under westerly upperwind, a line of discontinuity of wind is made of this outburst and the wind from the anticyclone generating near Kumamoto in the windward of the Kyushu Mts. A band cloudappears along this line. Under north-northwesterly upper wind, the cold air current from the anticyclone generating near Hita in the wind ward of the Kyushu Mts. is brought to thewest of this outburst, where a band cloud appears.