This paper has presented not only the spatial coverage change of climate extreme events in summer and winter seasons during the period of 2000-2017, but also their future projections in 2021-2100, South Korea through analysis of a Combined Climate Extreme Index (CCEI). The CCEI quantifies the spatial coverage of climate extreme events based on a set of five indicators. MK (Modified Korean)-PRISM (Parameter-elevation Regression on Independent Slopes Model)v1.2 (1×1km) and RCP scenario data (1×1km) were applied to CCEI. Results indicated that in average, 21.7% of the areas in the summer and 23.6% in the winter experienced climate extremes from 2000 to 2017 regardless of types of climate extreme events in South Korea. The summer of 2003 and 2009 was relatively cool and humid, while the summer of 2014 and 2015 was cool and dry and the summer of 2016 was warm and dry. The extreme events with much above normal maximum and minimum temperature during the study period were detected but not much below normal maximum and minimum temperature after 2015. For RCP2.6 and RCP8.5 scenarios, there were statistically significant trends with spatial coverage expansion of climate extreme events in the future. It might be concluded that climate extreme events in the summer and winter seasons were affected simultaneously by two or more indicators than a single indicator in South Korea.

The purpose of this study is to characterize the synoptic climatic patterns of extreme humansensible temperature (HST) events in Jeju Island, Korea under a subtropical climate condition as well as to examine their teleconnections with the large-scale climate systems. According to the extreme case analysis of the recent 30 years (1988-2017) data sets, the maximum daily average HST in the coastal areas of Jeju Island can rise up to about 40°C in mid-summer and even up to about 48°C during mid-daytime. These extreme HST events occur when the expansion of subtropical Pacific high pressure toward East Asia as well as the poleward shift of the Changma front provides hot and humid conditions over Jeju Island surrounded by seas, particularly in La Niña years with a positive (+) Arctic Oscillation mode. In contrast, the intensified western high and eastern low dipole pressure pattern in mid-winter, which accompanies the downward shear of upper tropospheric cold air toward the southern region of the Korean Peninsula under a negative (-) Arctic Oscillation mode, provides favorable conditions for frequent low HST extreme events. These conditions can lower daily average HST as much as -10°C in the coastal region of Jeju Island, and lower nighttime HST by -25°C on the peak areas of Mt. Halla due to wind chill effects. These findings will be used as a base for establishing prediction and warming systems of extreme HST events on Jeju Island, which is needed to mitigate the damage to the lives of Jeju residents and tourists under climate change.

Regional climate simulations for the CORDEX East Asia domain were conducted between 1981 and 2100 using five models to project future climate change based on RCP2.6, 4.5, 6.0, and 8.5 scenarios. By using the ensemble mean of five model results, future changes in climate zones and four extreme temperature events of South Korea were investigated according to Köppen-Trewartha’s classification criteria. The four temporal periods of historical (1981-2005), early future (2021-2040), middle future (2041-2070), and late future (2071-2100) were defined to examine future changes. The analysis domain was divided into 230 administrative districts of South Korea. In historical (1981-2005) period, the subtropical zones are only dominant in the southern coastal regions and Jeju island, while those tend to expand in the future periods. Depending on the RCP scenarios, the more radiative forcing results in the larger subtropical zone over South Korea in the future. The expansion of the subtropical zone in metropolitan areas is more evident than that in rural areas. In addition, the enlargement of the subtropical zone in coastal regions is more prominent than that of in inland regions. Particularly, the subtropical climate zone for the late future period of RCP8.5 scenario is significantly dominant in most South Korea. All scenarios show that cold related extreme temperature events are expected to decrease and hot related extreme temperature events to increase in late future. This study can be utilized by administrative districts for the strategic plan of responses to future climate change.

본 연구에서는 제주도 극한기후사상의 특성 및 변화를 파악하고, 이에 대한 전구연평균기온과 대규모 기후변동성의 영향을 조사하였다. 제주도의 연평균기온, 연평균 최고기온, 연평균 최저기온은 모두 상승하지만, 연강수량은 뚜렷한 변화경향이 나타나지 않았다. 더위 관련 지수 중 온난야율, 열대야일수는 제주와 서귀포에서, 열대일수는 서귀포에서 증가했고, 추위 관련 지수인 서리일수는 제주, 서귀포, 성산에서 감소하였다.호우관련 지수인 10mm 이상 강수일수, 5일 최대강수량, 95퍼센타일 호우율은 서귀포에서만 증가경향이 나타났다. 제주의 겨울 강수일수와 서리일수는 전구연평균기온, Niño 3.4 해수면온도 아노말리, 남방진동지수, 북극진동지수와 밀접한 관련이 있어서, 변동성의 설명력이 높게 나타났다. 또한 온난화가 지속될 경우 제주도의 온난야율과 열파지속일수가 모든 지점에서 증가할 것으로 전망되었다.