The purposes of this study were to classify detailed climate types over the Republic of Korea (ROK) and to delineate their climate characteristics using the new normals of 1991-2020 for 219 weather stations. Total five climate types, Cfa, Cfb, Cwa, Dwa, and Dwb were identified in ROK based on the Köppen’s climate classification criteria. Subtropical climate types, Cfa or Cwa types were broadly covered with 79.9% of 219 stations and the most of remaining stations were included in Dwa types which had a very cold winter and hot summer with wet conditions. In the Trewartha classification, four climate types were identified, one subtropical Cfa, and three temperate Doa, Dca, and Dcb types. Dcb types were found at four stations (Daegwallyeong, Taebaek, Jinburyeong, and Sabuk) in Taebak mountains indicating the extent of cool summer climate types with more stations in mountain areas. The climate characteristics by climate types only were presented the results from the Trewartha classification with the new normals and 66 ASOS stations because Köppen’s climate classification was not appropriate for ROK. The annual mean precipitation of Cfa was the greatest while Dcb the lowest among four types. The annual range was the greatest at Dca types while the smallest at Cfa due to the geographical varieties. More detailed climate types were located in ROK with 219 weather stations and the new normals (1991-2020). However, there were some limitation applying the criteria of Köppen’s and Trewartha’s climate classification to a very complex topographical region.

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.