The present study documents Korean climate variability in relation to various climate factors for improving operational long-range forecast. Since the dynamical model has some limitations in predicting mid-latitude climate accurately, the statistical analysis on the Korean climate will complement the weakness of the climate prediction based on the dynamical model. In particular, statistical analysis based on observational data facilitates more physically reliable interpretation of the dynamical model results. Based on this background, the present study investigates the statistical relationship of Korean climate with various climate factors, such as El Niño-Southern Oscillation (ENSO), snow cover extent (SCE), or large-scale atmospheric circulations. Analyses are conducted on four specific subjects: 1) monthly climate variability over Korea during different phases of ENSO evolution; 2) the effect of Eurasian snow cover variability in relation to warming trends and Arctic Oscillation; 3) distinct mechanism of Korean surface temperature variability

during early and late summer; and 4) three types of warming over Korea based on the atmospheric circulation pattern.

The first subject documents monthly temperature and precipitation anomalies over Korea during different evolution phases of ENSO. The evolution process of ENSO can be classified into two groups based on whether El Niño turns into La Niña in the subsequent year. The first group involves the transition process from El Niño to La Niña, while the second group shows prolonged El Niño or neutral

conditions after the mature phase of El Niño. Since the mid-latitude atmospheric responses, as well as the equatorial heating anomalies for the two groups of ENSO, differ from each other, the ENSO-related temperature and precipitation anomalies over Korea are investigated separatedly for the two ENSO evolution groups. In particular, this study focuses on the entire monthly evolution of the temperature and precipitation over Korea during the different phases of ENSO.

The second subject is the two distinct modes of snow cover variability over Eurasia and their impacts on the Korean climate. The first mode of Eurasian SCE represents a seasonally asymmetric trend between spring and fall. The spring SCE shows a decreasing trend, while the fall SCE, particularly in October, exhibits a clear increasing trend. This seasonally asymmetric trend of SCE is closely linked to Arctic sea ice decline accompanied by warming in the northern Eurasia. On the other hand, the second mode of Eurasian SCE is closely related to Arctic Oscillation (AO), which is a dominant mode of Northern Hemisphere atmospheric variability. Detailed descriptions of the two distinct modes of Eurasian SCE and their impacts on Korean temperature and precipitation are presented.

The third subject is the distinct mechanism of Korean surface air temperature (SAT) variability during early and late summer. Korean SAT exhibits a distinguished sub-seasonal variation, showing remarkable differences between early summer (June) and late summer (July and August). The SAT variability during early summer is significantly influenced by the global warming signal, while the contribution of the global warming signal is insignificant during late summer. The residual variability of the early summer, which is an independent component of the global warming trend, is closely related to the atmospheric circulation over East Asia. However, this structure does not originat from remote oceanic SST forcing. During the late summer, the Korean SAT is dominantly regulated by the atmospheric variability induced by the Pacific SST forcing.

The fourth subject is the classification of the warming event over Korea based on the atmospheric circulation pattern. The three types of atmospheric circulation patterns in relation to warming over Korea are identified as the wave type, Pacific Japan (PJ) type, and North Pacific (NP) type. The intensity and duration of warming over Korea are investigated for the three types of warming along with the large-scale atmospheric and oceanic circulation patterns. These analyses will provide the statistical basis for improving long-range forecast over Korea.

1. 서론

2. 연구 자료 및 방법

2.1 연구 자료

2.2 분석 방법

3. ENSO의 진화 과정에 따른 우리나라 월별 기온과 강수 특성

3.1 ENSO 진화 과정에 대한 분류

3.2 두 그룹의 ENSO 진화 과정에 따른 우리나라 월별 기온과 강수 특성

3.3 두 그룹의 ENSO 진화와 우리나라 기후에의 영향에 관한 APCC MME 예측 성능 분석

4. 유라시아 지역 눈 덮임 변동성과 우리나라 기후에의 영향

4.1 유라시아 눈 덮임 변동성 – 첫 번째 모드: 계절별 비대칭적 추세 (seasonally asymmetric trend)

4.2 유라시아 눈 덮임 변동성 – 두 번째 모드: 북극 진동 (Arctic Oscillation)과 관련된 변동성

5. 우리나라 여름철 월별 기온 변동성의 특징

5.1 우리나라 여름철 기온 변동 특성

5.2 6월 기온 변동 특징

5.3 7~8월 기온 변동 특징

6. 우리나라 여름철 고온 사례 분류 및 특성 분석

6.1 우리나라 여름철 고온 현상에 영향을 미치는 세 가지 대기 패턴

6.2 세 가지 고온 사례와 관련된 대규모 순환장의 특징

7. 결론 및 토론

REFERENCE