ヨーロッパの冬から春にかけての 低気圧活動に関する事例解析（2000年を例に）

Although the extratropical cyclone is one of the basic systems that characterize the weather and climate in mid-latitude regions with the large meridional temperature gradient, its activity and characteristics would be greatly influenced by the seasonal transition and regional differences of the mean atmospheric fields such as between Europe and East Asia. Furthermore, detailed knowledge of the daily cyclone activity would help to understand deeply the differences of regional climatology including seasonal cycles among various areas. In such interest, the present study performed a case study on the cyclone activity around Europe from winter to spring of 2000. In winter, intraseasonal variation of the Icelandic Low was dominant. In the stage when such intraseasonal-scale Icelandic Low approached to the northwestern Europe, the several lows passed eastward with a few days interval around the intraseasonal-scale low pressure area or its southern edge where the baroclinicity was relatively strong. It is also noted that their center pressure was rather low (below 980hPa). After April, when the seasonal mean Icelandic low had disappeared, different types of the intra-seasonal-scale cyclones and anticyclones were dominantly observed. In the lower SLP stage of the intraseasonal variation in Europe, the low to the southwest of England in the middle of April was of the equivalent barotropic structure and persisted for about ten days. On the other hand, high pressure area extending from England to the northern coast of Germany also persisted for about half month. The southern half of that high area was also of equivalent barotropic structure with warmer air there.