Western coastal area of Chungnam, including Cheonsu Bay and Garorim Bay, has suffered from hot and cold extremes. In this study, the extreme sea surface temperature on the western coast of Chungnam was analyzed using the quantile regression method, which extracts the linear regression values in all quantiles. The regional MOHID (MOdelo HIDrodinâmico) model, with a high resolution on a 1/60o grid, was constructed to reproduce the extreme sea surface temperature. For future prediction, the SSP5-8.5 scenario data of the CMIP6 model were used to simulate sea surface temperature variability. Results showed that the extreme sea surface temperature of Cheonsu Bay in August 2017 was successfully simulated, and this extreme sea surface temperature had a significant negative correlation with the Pacific decadal variability index. As a result of future climate prediction, it was found that an average of 2.9oC increased during the simulation period of 86 years in the Chungnam west coast and there was a seasonal difference (3.2oC in summer, 2.4oC in winter). These seasonal differences indicate an increase in the annual temperature range, suggesting that extreme events may occur more frequently in the future.

본 연구에서는 강한 한파가 발생했던 2018년과 온난 한파가 발생했던 2019년의 기온에 따른 수온의 반응 및 지연시간과 북풍계 열 바람 빈도와의 상관관계를 분석하였다. 사용된 시간 자료는 국립수산과학원에서 제공하는 7개 지점 해역별 수온자료와 수온관측소 인 근 7개 지점 AWS 기온자료를 이용하였다. 관측되지 못한 자료는 내삽법으로 근사값을 계산하였고, FIR Filter를 이용하여 자료의 주기성을 파악하였다. 그 결과, 강한 한파가 발생했던 2018년은 북풍계열 바람을 통해 차가운 공기가 남하하면서 기온을 하강시켜 전 해역에 저수온을 유발한 반면 온난 한파가 발생했던 2019년은 평년 수준의 기온으로 하강하였지만 수온은 크게 변화하지 않았다. 강한 한파가 발생했 던 2018년 기온 하강에 따른 수온의 지연시간은 평균 14시간으로 0.7 이상의 높은 상관성을 나타냈고 온난 한파가 발생했던 2019년은 평균 지연시간이 20시간으로 0.44-0.67 사이의 상관성을 보였다. 본 연구를 통해 해역별로 기온 하강에 따른 표층수온의 반응을 해석하였고 지연시간을 파악함으로써 양식생물의 피해를 최소화하고 한파 피해의 신속한 대응에 기여할 수 것으로 기대한다.

본 연구는 한반도에서 Proto3 모형을 수행하기 위하여 필요한 3가지 기후인자 지도, 1. 식물 내한성 구역, 2. 쾨펜- 가이거 기후구, 3. 연누적강수량 영역에 대한 한반도 지도를 1 km 해상도로 제작하였다. Worldclim V2와 한반도 30 년 평균 기상대 데이터를 이용하여 한반도 최저극값온도 격자를 제작하였으며, 이를 활용하여 한반도 식물 내한성 구역 격자지도를 제작하여 Proto3에 이용하였다. 쾨펜-가 이거 기후구 지도는 Beck et al. (2018)의 쾨펜-가이거 기후구 지도를 Proto3에 적합하게 변형하였으며, 연누적강수량 영역은 Worldclim V2를 활용하여 제작하였다. 제작된 Proto3 기후 인자 지도를 활용하여 외래잡초 별나팔꽃의 정착 확산 가능 지역을 예측한 결과, 남한 대부분의 지역과 북한의 황해도를 포함한 남쪽 지방까지 전체 한반도 격자의 50.7%가 정착, 확산 가능지역으로 예측되었다. 본 결과는 별나팔꽃의 위해성 평가 및 관리 체계 수립 등에 활용가능할 것으로 판단된다.

Recently, measuring instruments for SHM of structures has been developed. In general, the wireless transmission of sensor signals, compared to its wired counterpart, is preferable due to the absence of triboelectric noise and elimination of the requirement of a cumbersome cable. However, in extreme environments, the sensor may be less sensitive to temperature changes and to the distance between the sensor and data logger. This may compromise on the performance of the sensor and instrumentation. Therefore, in this paper, free vibration experiments were conducted using wireless MEMS sensors at an actual site. Measurement was assessed in time and frequency domain by changing the temperature variation at(- 8℃, - 12℃ and - 16℃) and the communication distance (20m, 40m, 60m, 80m).

Extreme temperatures and precipitations are expected to be more frequently occurring due to the ongoing global warming over the Korean Peninsula. However, few studies have analyzed the synoptic weather patterns associated with extreme events in a warming world. Here, the atmospheric patterns related to future extreme events are first analyzed using the HadGEM3-RA regional climate model. Simulations showed that the variability of temperature and precipitation will increase in the future (2051-2100) compared to the present (1981-2005), accompanying the more frequent occurrence of extreme events. Warm advection from East China and lower latitudes, a stagnant anticyclone, and local foehn wind are responsible for the extreme temperature (daily T>38 o C) episodes in Korea. The extreme precipitation cases (>500 mm day−1 ) were mainly caused by mid-latitude cyclones approaching the Korean Peninsula, along with the enhanced Changma front by supplying water vapor into the East China Sea. These future synoptic-scale features are similar to those of present extreme events. Therefore, our results suggest that, in order to accurately understand future extreme events, we should consider not only the effects of anthropogenic greenhouse gases or aerosol increases, but also small-scale topographic conditions and the internal variations of climate systems.

본 연구에서는 2016년 8월 해역(서해, 남해, 동해)별로 기온에 따른 수온의 반응 및 지연시간을 연구하였다. 사용된 1시간 간 격의 자료는 국립수산과학원에서 제공하는 8개 지점 해역별 수온자료와 수온관측소 인근 8개 지점 기상청 AWS 기온자료를 이용하였 다. 내삽법을 이용하여 관측되지 못한 자료값을 계산하였고, FIR Filter를 이용하여 조류 및 일변화 영향을 제거하여 자료의 주기성을 파 악하였다. 남해 2 지점은 기온과 수온이 유사한 주기성을 가졌으며, 0.8의 높은 상관계수와 약 50시간의 지연시간을 나타냈다. 서해 4 지점은 얕은 수심과 조석차로 인해 기온변화에 따른 수온의 지연시간이 약 12시간으로 반응시간이 다른 해역에 비해 빨랐다. 동해는 해안지형에 따른 환경적 요인과 깊은 수심으로 인해 기온과 수온의 상관성을 보이지 않았다. 본 연구를 통해 AT-SST 간의 지연시간을 파악함으로써 양식생물의 피해를 최소화 하는데 기여할 것이고, 수산업에서의 폭염 피해에 대한 신속한 대응 체계가 마련될 것이라 기 대한다.

The present study aims to analyze climate change and trend of extreme temperature events occurred over the Republic of Korea. The observation data used are daily average, maximum, and minimum temperature from 6 weather stations for the period of 1912-2020. Seven extreme indices regarding frequency and extreme value of temperature are calculated in seasonal and annual time range. In addition, hot extremes and their changes by four physical terms that include information on the annual mean temperature, the amplitude of the annual cycle, the diurnal temperature range and the local temperature anomaly on the day of the extreme are analyzed. The climatology for the analysis is updated to the new normal year of 1991-2020. Consistent with the previous findings, statistically significant change was detected in the indices of annual lowest daily minimum temperature, annual extreme temperature range, frequency of daily minimum temperature below -12℃ and 10%ile(TN10p) during winter. Due to the gradual decrease of the occurrence days regarding the extreme minimum temperature during winter, the frequency calculated by the relative threshold in extreme high temperature during summer prevail since 1990s. Indices related with extreme high temperature had larger low-frequency variability than significant climate change during the analysis period. However, the assessment of hot extremes according to the terms describing mean, variability and tails during the new normal year of 1991-2020, significant increasing trend was detected not only in the annual mean and the amplitude of the seasonal cycle, but also in the daily hot extreme anomaly.

The purpose of this study is to explore spatio-temporal patterns of extreme low human-sensible temperature (HST) across Mt Halla (1,950m), Korea. To do this, decadal (2011/12-2020/21) averages of daily or hourly windchill index (WCI), which quantifies HST considering the combined effects of low temperature and strong wind, are calculated for 24 weather stations in Mt Halla. Time series of decadal average daily mean show that extreme low HST events with moderate risk level (-27~-10°C) occur in mid-winter (mid-January~early February) around the high mountainous areas of Mt Halla, while such risk does not exist in the low-elevated coastal regions of Jeju Island under subtropical climate. Strong wind around the subalpine climate belt lowers HST by 5°C than air temperature in mid-winter. In extreme cases when the advection of northerly cold wind is intensified by the west high-east low pressure pattern in East Asia, the HST around the peak of Mt Halla can be lowered to high risk level (-39~-28°C) in the early morning times of mid-winter days. These information about mountain bioclimate may help establish mountain extreme climate warning systems, which are needed to protect mountaineers from potential life-threatening accidents caused by extreme low HST events over high mountains such as Mt Halla.

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.

We estimated changes in temperature-related extreme events over South Korea for the mid and late 21st Century using the 122 years (1979-2100) data simulated by RegCM4 with HadGEM2-AO data as boundary conditions. We analyzed the four extreme events (Hot day: HD, Tropical day: TD, Frost day: FD, Icing Day: ID) and five extreme values (Maximum temperature 95/5 percentile: TX95P/TX5P, Minimum temperature 95/5 percentile: TN95P/TN5P, Daily temperature range 95 percentile: DTR95P) based on the absolute and relative thresholds, respectively. Under the global warming conditions, hot extreme indices (HD, TD, TX95P, TN95P) increase, suggesting more frequent and severe extreme events, while cold extreme indices (FD, ID, TX5P, TN5P) decrease their frequency and intensities. In the late 21st Century, changes in extremes are greater in severe global warming scenario, RCP8.5 rather than RCP4.5. HD and TD (FD and ID) are expected to increase (decrease) in the mid 21st Century. The average HD is expected to increase by 14 (17) days in RCP4.5 (8.5). All the percentile indices except for DTR95P are expected to increase in both RCP4.5 and RCP8.5. In the late 21st Century, HD and TD are significantly increased in RCP8.5 compared to RCP4.5, but FD and ID are expected to be significantly reduced. HD is expected to increase mainly in the southwestern region, twice (+41 days) in RCP8.5. TD is expected to increase by 17 days in RCP8.5, which is 5 times greater than that in RCP4.5. TX95P, TN95P and TX5P are expected to increase by about 2°C and 4°C in RCP4.5 and RCP8.5, respectively. TN5P is expected to increase significantly by 4°C and 7°C in RCP4.5 and RCP8.5, respectively.

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 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.

We studied the distribution of air temperature using the high density urban climate observation network data of Daegu. The observation system was established in February 2013. We used a total of 38 air temperature observation points (23 thermometers and 18 AWSs). From the distribution of monthly averaged air temperatures, air temperatures at the center of Daegu were higher than in the suburbs. The daily minimum air temperature was more than or equal to 25℃ and the daily maximum air temperature was more than or equal to 35℃ at the elementary school near the center of Daegu. Also, we compared the time elements, which are characterized by the diurnal variation of surface air temperature. The warming and cooling rates in rural areas were faster than in urban areas. This is mainly due to the difference in surface heat capacity. These results indicate the influence of urbanization on the formation of the daily minimum temperature in Daegu.

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.

Extreme temperature has direct and indirect effects on Human Health, and usually influences negatively. This study analyzes the correlation between extreme temperature and excess mortality caused by cardiovascular disease in Seoul. Excess mortality correlates with daily maximum temperature, especially daily excess fatality over two standard deviations, has a strong positive correlation. On the other hand, daily minimum temperature is not significantly related with excess death. Recently, significance of the correlation coefficient of high temperature in August decreases because of the heat wave preparation.

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.

This study was performed to investigate the enhancement of immunomodulatory activities of Lithospermum erythrorhizon by extreme process. The extracts are WE100 (water extract for 24 hours at 100℃), WE80 (water extract for 24 hours at 80℃), EE (70% ethyl alcohol extract for 24 hours at 80℃) and EPE (extreme process for 30 minutes at 25℃, 500 MPa after 70% ethyl alcohol extracts for 3 hours at 40, 50, 60℃). Extraction yield was increased up to 5~10% by extreme process, compare to the normal extraction such as water solvent extraction, 70% ethyl alcohol solvent extraction. The cytotoxicity of the extracts was showed in the range of 12.68~15.89% at 1.0mg/ml for human lung cell (HEL299). The EPE40 was showed the lowest cytotoxicity 12.68%. The EPE60 extracted by extreme process increased the growth of human B and T cells up to 12.12×104 cells/ml and 14.88×104 cells/ml, respectively and the EPE60 greatly increased the cytokine secretion of both IL-6 and TNF-α. The extracts by extreme process also exhibited higher levels of nitric oxide production from macrophages than the lipopolysaccaharides. It can be concluded that Lithospermum erythrorhizon has immune activities and The extreme process could increase higher immune activities possibly by immunomodulatory compounds.

최근 도시는 지구온난화와 도시열섬효과의 가중으로 기온상승이 뚜렷하며, 지표면의 대부분이 아스팔트나 콘크리트 재질의 불투수층으로 녹지에 비해 많은 열을 흡수 및 방출하므로 도시에 거주하는 대다수의 시민은 고온 환경에 노출될 가능성이 증가하고 있다. 하지만 현재 국내는 고온 환경에서 인체가 받는 열부하량에 대한 연구가 활발하지 않은 실정이다. 이에 본 연구에서는 고온 환경에서 발생할 수 있는 인명피해를 저감하고자 하는 방재적인 측면에서 인체가 받을 수 있는 열부하량을 간접적으로 평가할 수 있는 흑구온도 관측을 실시하였다. 2012년 하계 집중관측을 통해 흑구온도의 특성 및 표준흑구온도계와 자동관측장비로 개발된 WBGT-K200에서 관측된 흑구온도를 비교분석함으로써 방재적인 측면에서 효율성이 높은 장비를 파악하고자 하였다. 본 연구의 주요결과는 다음과 같다. 첫 번째, 흑구온도는 일사량이 강할수록 강수량이 적을수록 풍속이 약할수록 증가하는 특성을 보였으며, 그 중에서도 일사량에 가장 민감하게 반응하였다. 두 번째, 관측 장비의 특성 상 흑구 내에 물을 채우지 않는 WBGT-K200은 흑구 내에 물을 채우는 표준흑구온도계에 비해 열전도율이 높으며, 비열이 낮은 특성을 보였다. 세 번째, 일사량이 급증하는 11～14 LST사이에 WBGT-K200의 흑구온도가 비교적 높게 나타났다. 이와 같은 결과를 바탕으로 하계 고온 환경에서 발생할 수 있는 인명피해를 저감하기 위한 방재적인 측면에서 흑구 내에 물을 채우지 않고, 일사량이 증가하는 시간대에 흑구온도가 상대적으로 높게 나타난 WBGT-K200을 사용하는 것이 적합하다고 판단된다.