岡山大学 地球科学研究報告
Published by Okayama University Earth Science Reports Editorial Committee

東アジアとの比較の視点でみたヨーロッパにおける低気圧活動と広域場の季節サイクル(序報)

瀧川 優実 岡山大学教育学部(理科)
垪和 優一 岡山大学大学院教育学研究科自然教育学系(理科)
松本 健吾 岡山大学教育学部(理科)
加藤 内藏進 岡山大学大学院教育学研究科自然教育学系(理科)
抄録
 Preliminary analyses on the seasonal cycles of the large-scale atmospheric mean fields and the cyclone activity in Europe were performed based mainly on the NCEP/NCAR re-analysis data, at the viewpoint comparing with those in East Asia.  As for the climatological monthly mean fields (1981~2010), the meridional temperature gradient in East Asia presents striking seasonal change with the maximum in winter and the minimum in summer. It is interesting that such transition from winter to summer and that from summer to winter occur rather rapidly accompanied by the great temperature increase around April to June and the decrease around October to November, respectively, in a wide region of 40~70N. On the other hand, the temperature gradient in Europe is significantly smaller with slight seasonal change than that in East Asian winter.  By the way, in spite of the above difference of the horizontal temperature gradient between Europe and East Asia, the cyclone activity does not seem to be so weak even around Europe. Thus, the seasonal cycles of the characteristics of the cyclones and their environmental fields around Europe were examined. At the first step, we analyzed the daily cyclone activity in Europe for January and July of 2000. Many low pressure centers at the surface level appeared in both January and July. Referring also to the daily maps of sea level pressure and geopotential height at 500 hPa level, we found that not only the cyclones corresponding to the baroclinic instability waves, but also to the cold vortices which amplitudes increased with height appeared frequently. Moreover, it is interesting that the large-scale cold vortex, which embeds the shortwave trough with the low center at the surface level, appeared in the northern Europe in July as in East Asian winter, when such multi-scale systems sometimes bring the persisting heavy snowfall events in the Japan Sea side of the Japan Islands.
キーワード
seasonal cycle
cyclone activity
Europe and East Asia
ISSN
1340-7414
NCID
AN10506284
NAID