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 examine the trends of extreme temperature events in East Asia over the past 40 years (1979-2018) and their potential relationships with recent changes in the Northern Hemisphere cryosphere. Analyses of Sen’s slope and Mann-Kendall tests are performed for time series data of extreme temperature events extracted from NCEP-DOE reanalysis II Gaussian grid daily 2-m air temperature data. As the result, it is found that extreme high temperature events exceeding the 99th percentile show more noticeable increasing trends than the magnitude of the decreasing extreme low temperature events below the 1st percentile particularly in Mongolia, Korean Peninsula and southern China due to unexpected cold events since the late 2000s. Correlation analyses based on Kendall’s tau indicate that the reduction of spring-early summer Eurasian snow cover (data from Rutgers University Global Snow Lab.) may lead to the increasing tendency of extreme high temperature events in East Asia through snow albedo feedbacks, while paradoxically the reducing autumn-early winter Arctic sea ice (data from NSIDC) due to global warming seems to cause more frequent extreme low temperature events in recent years through the amplification of Rossby waves. Thus, it is needed to continue monitoring the feedbacks between changing Arctic cryosphere and East Asian climate systems in the warmer 21st century.

This study aims to analyze the change of onset and end dates of extreme temperature events and examine their relationships with global warming. The data used for this study are daily maximum temperature, daily minimum temperature, and global mean temperature anomaly. Results were similar to the trend of global temperature, showing that the onset date of extreme high temperature is advanced while the end date of extreme high temperature is delayed. Also, the change of onset (end) dates of extreme low temperature were clear, with coming later (earlier). There is more distinct change in extreme low temperature than extreme high temperature. The length between onset date and end date of extreme high (low) temperature is significantly longer (shorter). The onset (end) date of extreme high temperature has a negative (positive) relationship with global mean temperature. The onset (end) date of extreme low temperature has a positive (negative) relationship with global mean temperature. It might be concluded that the change of onset and end date of extreme temperature in South Korea has been affected by global warming.

The changes in extreme daily rainfall totals in Punjab Province, Pakistan, during the period (1981- 2014) are examined in this study. The analysis was focused on the extreme annual and monthly rainfall events, by processing the exceeding of the daily rainfall over various thresholds, which are indicators for the incidence of extreme rainfall events. To analyze the changes in extreme rainfall events and trends of the time series of the annual number of extreme rainfall days (%) the thresholds of 30mm and 50mm has been estimated. Evidence from the twelve stations considered shows that there is an increase in annual number of extreme rainfall days (%) in dataset. These changes of heavy and extreme rainfall events pronounce significant environmental consequences which cause considerable impact on society.

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.

Persistent Extreme Temperature Events (PETEs) are defined in two steps; first, to define extreme temperature events, the 80th and 20th percentiles of daily maximum and minimum temperature were chosen. Then individual PETE was defined as an event which lasted three or longer consecutive extreme temperature days. In this study, we examined characteristics and changes of PETEs in Republic of Korea (ROK) using 14 weather stations with a relatively long-term period of data, 1954-2016. In ROK, PETEs lasted four-five days on average and occurred two-three times a year. PETEs lasted longer in summer than in winter and in maximum temperature than in minimum temperature. PETEs which lasted greater than seven days account for a greater proportion in summer than in winter. However, intensities of PETEs were greater in winter because of a larger temperature fluctuation. In both summer and winter, durations and intensities of persistent extreme high temperature events increased while those of persistent extreme low temperature events decreased. Changes of PETEs were closely related with both global warming and diverse large-scale climate variabilities such as AO, NAO and Nino 3.4.

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.

The purpose of this study is to characterize long-term (1973~2012) changes in intra-seasonal temperature and extreme low temperature events in winter observed at 61 weather stations in the Republic of Korea and their associations with changes in atmospheric circulation patterns around East Asia. Maps of long-term linear trends clearly show that both temperature means and extreme events in Korea have asymmetrically changed between early winter and late winter. In early winter, changes with statistical significance are less observable, while in late winter reductions in low extreme temperature events as well as increases in temperatures, particularly after mid-1980s, are obviously observed across the study region. Comparisons of tropospheric synoptic climatic fields before and after the mid-1980s demonstrate that in early winter of recent decades, active meridional circulation from the Arctic appeared in western Eurasia and Bering sea, while in late winter, zonal circulation around East Asia associated with positive Arctic Oscillation-like patterns prevailed. These results indicate that asymmetric changes between early and late winter temperatures in Korea are associated with intra-seasonally inconsistent atmospheric circulation patterns around East Asia.

영동 지역에서는 해마다 대설로 인한 피해가 발생하고 있다. 최근 2014년 2월에는 총 누적 강설량이 192.8 cm의 기록적인 폭설이 내렸으며, 이로 인해 영동 지역에 크고 작은 재해 피해(약 171억 원) 및 인명 피해(사상자 6명)를 야기했다. 뿐만 아니라 2011년(약 230억 원)과 2013년도(약 75억 원)에도 유사한 대설현상이 발생하여 지역 주민들에게 사회·경제적 손실을 초래하였다. 이에 따라 영동 지역에 재해 피해를 유발하는 대설현상의 특징과 그 피해 규모 및 피해 종류를 분석하여 영동 지역에서 발생하는 재해 피해를 예방하는 기초 자료를 제공하고자 한다. 최근 20년(1993~2012)기간 동안에 영동 지역으로 집중적인 적설량 분포를 보이고, 재해 피해를 입힌 사례는 총 5건이며, 1996년 2월, 1998년 1월, 2005년 3월, 2008년 1월, 그리고 2011년 2월 사례 등이다. 이 사례들에 대해 영동해안지역에 해당하는 강원도, 경상남도, 경상북도, 부산광역시, 그리고 울산광역시의 재해 피해를 분석한 결과, 강원도와 경상북도 지역에서는 모든 사례에서 재해 피해를 입었으며, 재해 피해에 가장 취약한 지역임을 알 수 있다. 이렇게 재해 피해를 일으키는 각 사례의 종관 배경을 살펴보면, 공통적으로 시베리아 고기압의 확장과 남쪽 기압골 또는 저기압의 영향을 받았으며, 1996년, 1998년, 그리고 2005년 사례의 경우, 500 hPa 고도에서의 상층 기압골이 통과하면서 저기압에 동반된 경압불안정과 북쪽 한기이류의 영향으로 북동 계열의 바람이 강화되는 특징이, 2005년과 2011년 사례의 경우에는 부산 및 울진 앞바다 부근에 부저기압이 형성되어 있는 특징이 있었다.

In this study, spatio-temporal patterns of seasonal precipitation and extreme precipitation events around Mt. Halla (1,950m) and their associations with elevation and aspect are examined based on daily precipitation data for the recent decade(2003~2012) observed at 24 weather stations in Jeju Island. Regression analyses show that annul total precipitation and the annual frequency of extreme precipitation events exceeding 80mm of daily precipitation increase with height by approximately 242mm/100m and 1.0day/100m, respectively. Seasonally, extreme precipitation events over the high mountain area mostly occur in summer (June~August) and also appear in other seasons including winter (December~February). The frequency of annual or seasonal extreme precipitation events as well as precipitation is higher in the southeastern or northeastern slope than in the southwestern or northwestern slope of Mt. Halla. These patterns are associated with the flow direction of moist air that ascends the slope of Mt. Halla when anticlockwise circulation of low pressure systems prevails. These findings provide primary information for developing the proactive strategies to mitigate potential flooding in the low-elevated coastal areas by extreme precipitation events over Mt. Halla

본 연구에서는 전형적인 엘니뇨와 새로운 형태의 엘니뇨 Modoki에 따른 한강유역의 여름철(6～9월) 강우량의 특성 변화를 분석하였다. 전형적인 엘니뇨 시기에는 대체로 여름철 강우량이 감소하였으며, 강우의 변동성도 비교적 크게 나타났다(CV=0.40). 반면에 엘니뇨 Modoki 시기에는 한강 대부분 유역에서 평년보다 강우가 증가하는 경향을 보였으며, 여름철 강우의 변동성은 작은 것으로 분석되었다(CV=0.23). 엘니뇨 Modoki 시기에는 한강 남부의 11개 중권역에서 통계적으로 유의한 강우의 증가를 보였고, 30 mm/day와 50 mm/day를 초과하는 중호우의 강우발생일은 각각 9.9일과 5.4일로 나타났으며, 전형적인 엘니뇨 시기보다 백분위 편차가 각각 17.74%, 50.94% 큰 것으로 분석되었다. 본 연구에서는 새로운 형태의 엘니뇨 Modoki가 전형적인 패턴의 엘니뇨 보다 한강유역의 여름철 수자원 변동에 민감하게 영향을 주고 있음을 확인하였으며, 향후 수자원의 계절적 변동과 불확실성이 큰 지역에서 안정적인 수자원 확보를 위한 기초자료로 활용이 가능하리라 사료된다.

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.

극치사상을 예측하기 위한 기존의 빈도분석 결과의 이용에 대한 많은 문제점들이 부각되고 있다. 특히, 통계적 모형을 이용하기 위해서 흔히 사용되는 점근적 모형 (asymptotic model)의 합리적인 검토 없는 외삽 (extrapolation)은 산정된 확률 값을 과대 또는 과소평가하는 문제를 일으켜, 예측결과에 대한 불확실성을 과다하게 산정함으로써 불확실성에 대한 신뢰도를 감소시키는 문제가 있다. 그러므로 본 연구에서는 국내에서 극치강우사상을 포함한