제주시 일 최고기온의 변동특성 분석

Abstract

Jejudo is a volcanic island surrounded by the sea to in all directions and located in the southern-most part of the Korean peninsula. Despite that its total area is 1,848.3㎢ smaller than other provinces, the Halla Mt. at the center of it makes the weather very variable and unique. The weather of Jejudo is difficult to forecast, especially in temperature. The errors between forecast and observation in temperature are mainly due to 1)wind direction and wind speed, 2)warm advection and 3)topographic effect. As to wind direction and wind speed, wind is a circulation of sea-land breeze. A difference of heat capacity between sea surface and land is a cause of that circulation, which affect greatly on spatial temperature distribution. Especially, in the weather station near the coast sea-land breeze has a great effect on the temporal temperature variation. The maximum and minimum temperatures are influenced by the sea breeze and land breeze, respectively. Next element is warm advection. Because that Jejudo is in the region of the prevailing westerlies, a temperature rises by warm advection from west. A topographical effect by the Halla Mt. accelerates temperature differences. It operates as Fohn, makes the temperature forecast difficult and affected mainly by the winds at 850 hPa. Fohn occurred by the strong southwestern winds and the Halla Mt. when the North Pacific high expands and the low pressure system passes by the north of Jejudo. It happens frequently in summer. When it occurred, the maximum temperatures at Jeju were generally higher by 4℃ than those at Seogwipo. Especially when the wind speeds recorded as more than 10 m/s, the temperature differences were 6~7℃. Consequently, when the southwestern winds at 850hPa in sounding profile observed at the Gosan weather station blows at 10kt~35kt the temperature differences between Jeju and Seogwipo is 4℃. On the other hand, when the wind blows more than 35kts, the differences become larger by 6~7℃.