Case Study on Characteristics of Heat Flux Exchange between Atmosphere and Ocean in the case of cP Expansion accompanying Snowfall over the Adjacent Sea of Jeju Island

This study is focused on the relationship between snowfall and the Bowen’s Ratio (sensible heat flux/latent heat flux) through calculation of heat exchange between air and sea for snowfall events in Jeju Island from 1993 to 2003. The four weather stations for this study are located at Jeju, Seoguipo, Seongsanpo and Gosan in Jeju Island. In order to improve the reliability of snowfall forecast, the Bowen’s Ratio for snowfall, which includes influences from the atmosphere such as wind, is compared with the temperature difference between air and sea for snowfall. As a results, in the case for fresh snowfall, the minimum temperature differences between air and sea were 10, 12.3, 11.5, and $14.3^{\circ}C$ at Jeju, Seoguipo, Seongsanpo and Gosan, respectively. The probabilities of fresh snowfall were 26, 29, 13, and $23\%$, respectively, when the temperature differences were higher than the previous values. On the other hand, the minimum Bowen ratios were 0.59, 0.60, 0.65 and 0.65 at Jeju, Seoguipo, Seongsanpo and Gosan, respectively. The probabilities of fresh snowfall were 33, 70, 31 and $58\%$ respectively, when the Bowen ratio is higher than those. The reason for this is because the probability of fresh snowfall with the Bowen ratio was higher than the probability with temperature difference between air and sea. This result occurred because heat exchange by wind increased the probability of snowfall, along with the temperature difference between air and sea, and the Bowen ratio. Therefore, snowfall forecast of Jeju Island is significantly influenced by the sea, whereas forecast with Bowen ratio seems to have higher reliability than that with the temperature difference between air and sea. The data analysis for the ten-year period $(1993\~2002)$ showed that when each fresh snowfall was within 0.0 to 0.9cm, the average Bowen’s ratio was 0.63 to 0.67, and when each fresh snowfall was 1.0 to 4.9 cm, the average Bowen’s ratio was over 0.72. Therefore, fresh snowfall shows a proportional relationship with the Bowen’s ratio during snowfall.

제주연안에 강설을 수반하는 대륙성 한기단 확장 시 대기와 해양간의 열교환 특성 사례 연구

본 연구는 1993년부터 2003년 동안 겨울철 제주도 지방에 눈이 내린 경우를 대상으로 대기가 해양으로부터 얻은 열교환량을 계산하여 보웬비(현열속/잠열속)와 강설간의 관계를 분석한 것이다. 대상지역은 제주도 4개 관측지점인 제주, 서귀포, 성산포, 고산이다. 적설 예측의 신뢰도를 높일 수 있는 방법을 찾기 위하여 바람과 같은 기상의 영향이 가미된 보웬비와 적설과의 관계를 해기차와 적설과의 관계와 비교해 보았다. 그 결과 신적설 시, 지역별 최저 해기차는 제주시, 서귀포, 성산포, 고산에서 각각 10.9, 12.3, 11.5, $14.3^{\circ}C$였고, 그 이상의 해기차에서 신적설 확률은 각각 26, 29, 13, $23\%$인데 비해, 신적설시 지역별 최저 보웬비는 각각 0.59, 0.60, 0.65, 0.65였고, 그 이상의 보웬비에서 신적설 확률은 33, 70, 31, $58\%$로 나타나 보웬비가 해기차보다 높은 확률을 보였다. 보웬비에 의한 확률이 해기차에 의한 확률보다 높게 나타나는 이유는 해기차에 의해 형성된 강설의 조건에 바람에 의한 열교환이 강설의 조건을 강화시킨 것이 보웬비에 나타났기 때문으로 생각된다. 10년$(’93\~’02)$간 자료를 분석한 결과 각 지역별 신적설이 $10.0\~0.9cm$ 일 때 평균 보웬비는 $0.63\~0.67$이고 신적설이 $1.0\~4.9cm$ 일때 평균 보웬비는 0.72 이상으로 조사되어 강설시 적설량과 보웬비는 비례관계가 있음을 알 수 있었다.