Heat Waves In Korea Research Articles

Heatwaves at work: typology and spatial distributions of occupations exposed to heatwaves in Korea

Heatwaves at work: typology and spatial distributions of occupations exposed to heatwaves in Korea

Causes on the 2018 record-breaking heatwave in South Korea: Compound impacts from recurrent large-scale atmospheric teleconnections

Abstract This study analyzed the causes of the extreme heatwave in East Asia in 2018, which brought a record-breaking event in South Korea in terms of the number of hot days and the intensity in history. Long-lasting atmospheric patterns were observed during the 2018 heatwave, and the patterns were similar to those known as the Pacific-Japan (PJ), Circum-global Teleconnection (CGT), and Arctic Oscillation (AO) patterns identified in a previous study. In 2018, all three patterns appeared to exhibit a strong positive phase. In particular, the PJ and AO Indices showed the highest values within the analysis period, having a major impact on the heatwave. According to a quantitative analysis through multi-linear regression (MLR) of how much each of the three patterns affects the heatwave, all three patterns of PJ, CGT, and AO have significant effects on the heatwave in Korea. The statistically reconstructed heatwave days (HWD) time series with the three indices by MLR account for 51% of the total variability at the interannual timescale. Especially in 2018, most of the occurred HWD could be restored using the three indices. Also, in 1994, when the three indices had a high peak, the number of HWDs was the second-longest ever, while in 1993, when all three indices had a low peak, the heatwave was the lowest. This study quantitatively examined whether the large-scale extreme heatwave in 2018 greatly increased because of PJ, CGT, and AO. This study suggests that extreme heatwave can occur again if three apparently independent atmospheric patterns appear at once in the future.

Factor analysis of recent major heatwaves in East Asia

Heatwaves (HWs) present a major hazard to our society and more extreme heatwaves are expected with future climatic changes. Hence, it is important to improve our understanding of the underlying processes that drive HWs, in order to boost our socioeconomic–ecological resilience. In this study, we quantified the influences of key driving factors (large-scale atmospheric circulation, soil moisture, and sea surface temperature) and their synergies on recent heatwaves in East Asia. We conducted a factor separation analysis for three recent HW events by constraining the key factors in the regional Weather Research and Forecasting model with their climatologies or pseudo-observations in different combinations. Our study showed distinct spatial variations in the HW-controlling factors in East Asia. The synergistic interaction of large-scale circulation and soil moisture was the most important factors in the 2013 Chinese HW. During the 2018 HWs in Korea and Japan, the same stagnant large-scale atmospheric circulation played a dominant role in driving the HW events. The land-atmosphere coupling via soil moisture, its interaction with circulation, and SST exhibited stronger influences during the Korean HW than the Japanese HW. Our analysis also revealed temporal variations in the factors driving Korean and Chinese HWs due to typhoon passage and other multiple processes over heterogeneous surfaces (i.e., topographically induced Foehn winds, large-scale warm advection from the warm ocean, spatial differences in soil moisture). Our findings suggest that future heatwave-related studies should consider interactive contributions of key factors, their interplay with surface heterogeneities of complex terrain.

Comparison of the opposite behaviours of Korean heatwaves with extreme hot sea surface temperatures in August 2016 and 2022

AbstractIn South Korea, an unprecedented heatwave occurred in August 2016. That year, sea surface temperature (SST) in the Korean marginal seas (KMS) was remarkably higher than that in climatology, and upper‐level anticyclonic circulations favoured this heatwave. More recently, similar conditions that can expect the frequent occurrence of heatwaves prevailed in August 2022. However, the opposite extreme phenomenon, heatwave days below climatology, occurred with the emergence of a stationary rainband in South Korea. This study aims to understand the two different behaviours of heatwaves in Korea under the same hot SST conditions in the KMS. The most pronounced difference between these two extreme cases is the existence of moisture flux related to the western North Pacific summer monsoon (WNPSM). Although the WNPSM is not generally highly correlated with temperature and precipitation in Korea, their relationship is particularly strong when hot SST conditions develop in the KMS. This SST condition, combined with the WNPSM, plays a role in determining this anomalous moisture flux in Korea. Enough tropical moisture flux occurred to build a stationary front with declining heatwave days during August 2022. In contrast, extremely dry and hot weather was more likely in 2016 due to inactive moisture fluxes from the western North Pacific.

A Study on the Segmentation of Heat Wave Warning Zones using Cluster Analysis

A heat wave countermeasure period was selected and operated to minimize the damage from heat waves in Korea. However, to this date, there are no clear ideas and methodology for selecting a heat wave countermeasure period, resulting in continuous budget expenditure incurred for its preparation and response activities. This requires an efficient selection of countermeasure periods. This study analyzed the time series data trend of heat index using Mann-Kendall and Pettitt test for cities and counties in Gyeongsangbuk-do, and it confirmed the current characteristics of increasing heat waves compared to- those in the past. In addition, K-means cluster analysis was applied to derive the city-wise heat wave characteristics. The cities and counties were classified into three based on the heatwave characteristics and starting point and ending point of each heat wave characteristic representing the years 2004 to 2021 between July 21 to August 11, July 16 to August 15, and July 11 to August 19. It was also confirmed that there was a significant difference from the heat wave countermeasure period (May 20~Sep 30) currently selected. Hence, in the future, economic losses may be minimized in terms of disaster preparedness and response through the selection of the heatwave countermeasure period reflecting temporal and spatial characteristics.

A Case Study of Bias Correction and the Dynamical Downscaling of CFSv2 S2S Forecasts Using a WRF Model: Heatwave in 2018 over South Korea

Extreme weather events caused by climate change affect the growth of crops, requiring reliable weather forecasts. In order to provide day-to-season seamless forecasting data for the agricultural sector, improving the forecasting performance of the S2S period is necessary. A number of studies have been conducted to improve prediction performance based on the bias correction of systematic errors in GCM or by producing high-resolution data via dynamic detailing. In this study, a daily simple mean bias correction technique is applied on CFSv2 (∼100 km) data. We then use case studies to evaluate how beneficial the precision of the high-resolution RCM simulation is in improving S2S prediction performance using the bias-corrected lateral boundary. Based on our examination of 45-day sequences of WRF simulations with 27–9–3 km resolution, it can be concluded that a higher resolution is correlated with better prediction in the case of the extreme heatwave in Korea in 2018. However, the effect of bias correction in improving predictive performances is not significant, suggesting that further studies on more cases are necessary to obtain more solid conclusions in the future.

Possible relationship between heatwaves in Korea and the summer blocking frequency in the Sea of Okhotsk

AbstractThis study examined the relationship between heatwaves in Korea and blocking in the Sea of Okhotsk (OK) region, which significantly influences the Korean climate in summer. According to the analysis, negative correlations were observed between the blocking frequency in the OK region and heatwave days (HWD) and the surface air temperature (SAT) in Korea over the past four decades (1979–2018). These negative correlations suggest that when the blocking frequency in the OK region increases in summer, the HWD and SAT decrease in Korea. This study selected 10 years of high blocking frequency years (high BF years) and 10 years of low blocking frequency years (low BF years) and analysed the differences between the two groups to explain the negative relationship between the HWD in Korea and the blocking frequency in the OK region. The difference between the two groups revealed strong anomalous anticyclonic and cyclonic circulations that developed in the north Siberia region and northeast Australia (NEA), respectively, throughout all layers in the troposphere. The large anomalous anticyclonic pattern in the North Siberia region was related to the blocking high, while the anomalous cyclonic pattern that developed in NEA was related to the East Asian summer monsoon (EASM) front. The difference in the sea surface temperature (SST) between the two groups was also analysed. In the North Atlantic Ocean, a tripole structure appeared with a cold anomaly in the high latitudes, a warm anomaly in the mid‐latitudes and a cold anomaly again in the low latitudes, which is a typical spatial distribution of the SST anomaly related to the positive North Atlantic Oscillation (NAO) phase.

폭염 피해 대조군 지역 분석

Since many people died of thermal disease in 2012 and 2018, the heatwave in Korea has been considered one of the serious disasters, which has led to a significant increase in research on disasters caused by heatwave. However, most previous studies have mainly focused on the relative vulnerabilities of demographic factors such as regional size or gender, age, and occupation. According to previous studies by other countries suffering from heatwave, the causes of heatwave disasters include not only demographic backgrounds but also the role of surrounding societies such as public services. This study found that 11 influencing variables showed acceptable correlation with heatwave victims, and five pairs of contrast areas were selected. Subsequently, public functions were analyzed in the selected contrast regions; however, in spite of concerns over the heatwave, the heatwave shelter in this area has not been well promoted or operated.

Occurrence of heatwave in Korea by the displacement of South Asian high

The South Asian high (SAH) index was defined using the 200 hPa geopotential height for 1973–2019. Of the movements of the SAH center in the north–south, east–west, northwest-southeast, and southwest-northeast directions, the movements in the northwest-southeast direction showed the highest positive correlation with heatwave days (HWDs) in South Korea. Thirteen years with the highest values in the northwestward shift of the SAH (positive SAH years) and 13 years with the highest values in the southeastward shift of the SAH (negative SAH years) were selected from a time series of SAH indices from which the linear trend was removed, and the differences between these two groups were analyzed. An analysis of vertical meridional circulation averaged along 120°–130° E showed that in the latitude zones containing Korea, anomalous downward flows with anomalous high pressures formed in the entire troposphere and coincided with a positive anomaly of air temperature and specific humidity. An analysis of stream flows and geopotential heights showed that in the positive SAH years, anomalous anticyclones developed in Korea, the North Pacific, North America, Western Europe, and the Iranian Plateau. These anticyclones had the wavenumber-5 pattern and showed more distinct barotropic vertical structures at higher altitudes, which resembled the circumglobal teleconnection (CGT) pattern. The maintenance of CGT depends on the interaction between the CGT circulation and the Indian summer monsoon (ISM), which has a major influence on the mid-latitude atmosphere. Strengthening of the ISM results in the formation of upper-level anomalous anticyclones in the northwestern Iranian Plateau and produces continuous downstream cells along the waveguide due to the Rossby wave dispersion. When diabatic heating by Indian summer monsoon precipitation is strengthened, the SAH is strengthened to the northwest of India, and a positive CGT pattern is formed. As a result, anomalous anticyclones formed in all layers of the Korean troposphere, resulting in heatwaves, tropical nights, and droughts exacerbated in South Korea.

The Role of the Pacific‐Japan Pattern in Extreme Heatwaves Over Korea and Japan

AbstractIn the Northwestern Pacific, the meridionally propagating Rossby waves, known as the Pacific‐Japan (PJ) pattern, is the dominant teleconnection pattern and is considered as a source of heatwaves in East Asia. In this study, the circulation and thermodynamic characteristics of these patterns were investigated based on daily timescale to evaluate their relationship with the likelihood of heatwaves in Korea and Japan. The investigations reveal that stations in Korea and Japan record approximately 90% increase in extremely hot days (Tmax > 35°C) during the positive PJ pattern events. According to thermodynamic budget, horizontal heat advection is a key factor for the observed near‐surface warming during the positive PJ. The circulation pattern during the positive PJ largely explains the enhanced warm advection and physical heating due to the increased insolation and adiabatic heating are secondary factors for near‐surface warming. This phenomenon is robustly observed regardless of the definition.

Performance Evaluation of CMIP5 and CMIP6 Models on Heatwaves in Korea and Associated Teleconnection Patterns

AbstractThis study assesses the performance of the Coupled Model Intercomparison Project (CMIP) models for simulating summer heatwaves in Korea during a historical simulation period (1979–2014) using four diagnostic indices that represent the teleconnection mechanism of summer heatwaves in Korea. Four skill metrics are used for the model evaluation, namely, relative error (RE), interannual variability skill‐score (IVS), correlation coefficient (CC), and total ranking (TR) based on daily maximum temperature (TMAX) in Korea and the four diagnostic indices. The results show that the REs of CMIP5 models do not differ significantly from those of the CMIP6 models while the IVSs in the CMIP6 models are significantly improved compared with the CMIP5 models. Observations show that the heatwave circulation index (HWCI) contributes more to the interannual variability in TMAX in Korea than that of the Indian Monsoon Rainfall Index (IMRI), indicating that the teleconnection from the northwestern Pacific is more important than that from northwestern India. Interestingly, the CMIP6 models simulate this property better than the CMIP5 ensemble. The higher TR of CMIP6 models than CMIP5 supports that CMIP6 models are better overall in simulating heatwaves in Korea and the associated diagnostic indices.

Multi-risk assessment of heat waves under intensifying climate change using Bayesian Networks

Continuous climate change has increased the intensity and frequency of abnormal weather, temperature fluctuations, and natural disasters, along with their subsequent damages. The temperature rise is related to the increased number of days with heat waves and tropical nights, which generate problems in many different areas. The risks from heat waves appear in multiple forms, such as disease severity and energy shortages. To respond effectively to such complex risks, it is necessary to analyze where and what risks occur. Recently, Bayesian Network methodology has been applied in various fields, and the causality and probability of occurrence of complex events can be evaluated. Particularly, it is suitable for fields, such as climate change and disaster because of its consideration to uncertainty. Therefore, in this study, multi-risk networks were built, and a multi-risk assessment using Bayesian Network was performed considering statistical probabilities. In addition, this study examined the change in future risks by reflecting the climate scenarios proposed by Intergovernmental Panel on Climate Change. The disease risks related to heat waves have increased with time, particularly in the areas adjacent to the coast, centering on the southeast side of South Korea. As for energy shortage, the risk increased in the region around Daegu, a city known for its high temperatures as well as in the Seoul metropolitan areas. Through this study, it is possible to improve the methodology for evaluating multi-risks, and the analyzed results will be able to provide support for effective responses to risks caused by heat waves in Korea.

Characteristics and Comparison of 2016 and 2018 Heat Wave in Korea

Characteristics and Comparison of 2016 and 2018 Heat Wave in Korea

Association Between Air Conditioning Use and Self-reported Symptoms During the 2018 Heat Wave in Korea.

ObjectivesThe purpose of this study was to investigate the health effects of air conditioning use during the 2018 heat wave in Korea, included the highest temperature ever recorded in the nation.MethodsThe participants in this study were 1000 adults aged 19 years and older recruited from across Korea. The participants were asked about their experience of symptoms of various diseases, disruptions of their daily lives, and use of air conditioning during the heat wave. The associations between air conditioning use during the heat wave and health outcomes were analyzed using the chi-square test and multiple logistic regression models.ResultsAmong participants who lacked air conditioning in the main space where they spent time outside the home, 33.9%, 8.1%, 43.5%, and 19.4% experienced symptoms of heat-related, cardiovascular, nervous system diseases, and air-conditioningitis, respectively. In comparison, participants who did have air conditioning outside the home experienced the same symptoms at proportions of 21.0%, 1.9%, 26.8%, and 34.2%, respectively (p=0.027, 0.007, 0.007, and 0.023, respectively). Among participants who had no air conditioner at home, 10.0% were absent from school or work due to the heat wave. In contrast, among participants who had an air conditioner at home, only 3.7% were absent as a result of the heat wave (p=0.007).ConclusionsWhen air conditioning was not used at home or in the main space where participants spent time outside the home during the 2018 heat wave, adverse health effects were more prevalent, but the risk of air-conditioningitis was reduced.

The effects of heat wave on health indicators of the elderly during 2018 heat waves in Korea

PDS 66: Climate change, Exhibition Hall (PDS), Ground floor, August 28, 2019, 1:30 PM - 3:00 PM Background/Aim: There has been growing concern about the effects of heat wave on health. However, the effect on the health indicators for vulnerable group has rarely been examined. We aimed to investigate the acute effects of heat wave on body temperature and blood pressure of elderly individuals living in poor housing conditions in rural areas. Methods: Indoor temperature, body temperature (BT), blood pressure, and sleep disturbance were repeatedly measured up to six times for each 104 elderly individuals living in four southern rural areas in South Korea during heat waves in 2018. Changes in the BT, systolic blood pressure (SBP) and diastolic blood pressure (DBP) according to variations in the indoor and outdoor temperature were analyzed using linear mixed effect models controlling for age, sex, drug use, and smoking. We also analyzed the health effects of heat wave from socioeconomic status. Results: The average of indoor temperatures measured during the study period was 30.5°C (range, 22.9~38.3°C) and that of daily maximum outdoor temperature 34.5°C (range, 29.5~37.5°C). Indoor temperature was higher in low-income group than relatively high-income group. BT increased by 0.05°C [95% confidence interval (CI), 0.03 to 0.06°C] with an increase in the indoor temperature of 1°C. The effect of increased indoor temperature on BT was greater in the elderly with hypertension and sleep disturbance. DBP generally decreased with increase in indoor temperature, while the DBP decrease in the elderly with hypertension showed a statistical significance [-0.41 mmHg (95% CI, -0.02 to 0.80 mmHg) per 1°C]. SBP increased as the indoor temperature increased, particularly for the elderly without air conditioner. Conclusions: The elderly with poor house condition are directly exposed to heat waves, while their vital signs respond sensitively to temperature increase indoors. More active strategies to cope with increasing heat wave are required, particularly for vulnerable group.

A System Dynamics Analysis of Urban Heat Waves

In this study, we analyzed the potential determinants of urban heat waves in Korea and their dynamic relationship using a system dynamics analysis approach. We developed an integrated causal loop diagram and identified the direct and indirect factors influencing urban heat waves. The followings are the main findings of this study. First, the rise of temperature in Korea is not simply due to the increase of impervious areas affected by urbanization but should be seriously recognized as a critical issue of heat waves which may lead to the annihilation of the areas. Second, for more accurate prediction of the temperature increase and development of effective policy responses, we need a new approach that focuses on a non-linear and dynamic relationship between urban heat wave process and urban safety. Third, it is critical to explore policy measures for maintaining socioeconomic conditions and improving the level of urban safety based on the multi-dimensional examination of causal relationships across various determinants for urban heat waves in South Korea.

여름철 낮 시간대 교통사고에 대한 고온의 영향

Climate change affects the occurrence of heat waves in Korea. Heat wave gives significant impacts not only to human health, but also adversely affects on traffic accidents both directly and indirectly. This study analyzed heat wave impacts on traffic accidents in summer time (JJA) from 2012 to 2017 timely. To consider some occupations work in earlier or later than regular working hour, 04~20h is set for this study. Generalized additive model is used to analyze the relation between the temperature and traffic accidents. The results showed that the traffic accidents in high temperature increases in 04~08h, 08~12h, and especially 18~20h. The percent difference for relative risk of traffic accidents is 2.34% (95% confidence interval: 1.140, 3.269) when the temperature increase by 1°C in 18~20h. The results of this study suggest some requirements for measures to prevent traffic accidents in the morning and evening hours with increasing temperatures.

Two Types of Heat Wave in Korea Associated With Atmospheric Circulation Pattern

AbstractThis study investigates heat wave variability over Korea during 1979‐2017. It is found that most of heat waves in Korea can be classified into two distinct types based on the spatial patterns of atmospheric circulation anomalies: the zonal wave (Z‐wave) type and the meridional wave (M‐wave) type. The Z‐wave type is accompanied by large‐scale atmospheric waves across the Eurasian continent, while the M‐wave type is associated with convective activities over the subtropical western North Pacific. The Z‐wave type occurs when the high‐pressure node of eastward propagating wave located around Korea and it seems that the associated wave energy could originate from North Atlantic Ocean. The M‐wave type, on the other hand, is driven by northward propagating wave train from subtropical western North Pacific to East Asia, which is triggered by anomalous convective activity over the subtropical western North Pacific. By analyzing thermodynamical as well as dynamical variables, detailed descriptions on the physical characteristics of two types of heat wave are presented in this study along with the possible implications for summer climate variability over Korea.

The Use of a Quasi-Experimental Study on the Mortality Effect of a Heat Wave Warning System in Korea.

Many cities and countries have implemented heat wave warning systems to combat the health effects of extreme heat. Little is known about whether these systems actually reduce heat-related morbidity and mortality. We examined the effectiveness of heat wave alerts and health plans in reducing the mortality risk of heat waves in Korea by utilizing the discrepancy between the alerts and the monitored temperature. A difference-in-differences analysis combined with propensity score weighting was used. Mortality, weather monitoring, and heat wave alert announcement data were collected for 7 major cities during 2009–2014. Results showed evidence of risk reduction among people aged 19–64 without education (−0.144 deaths/1,000,000 people, 95% CI: −0.227, −0.061) and children aged 0–19 (−0.555 deaths/1,000,000 people, 95% CI: −0.993, −0.117). Decreased cardiovascular and respiratory mortality was found in several subgroups including single persons, widowed people, blue-collar workers, people with no education or the highest level of education (university or higher). No evidence was found for decreased all-cause mortality in the population (1.687 deaths/1,000,000 people per day; 95% CI: 1.118, 2.255). In conclusion, heat wave alerts may reduce mortality for several causes and subpopulations of age and socio-economic status. Further work needs to examine the pathways through which the alerts impact subpopulations differently.

Multi-model event attribution of the summer 2013 heat wave in Korea

Abstract To assess the anthropogenic influence on the summer 2013 heat wave in Korea, this study employed a fraction of attributable risk (FAR) approach to three Atmospheric General Circulation Models (AGCMs) with a large ensemble simulation, participating in the C20C+ Detection and Attribution Project. Monthly and daily temperatures were compared between two experiments. The real world (ALL) experiments were simulated under the observed variations in sea surface temperature, sea ice, greenhouse gas, and aerosol concentrations, while the counterfactual world (NAT) experiments were performed under adjusted boundary conditions by removing anthropogenic warming and with preindustrial levels of greenhouse gases and aerosols. Results from the three AGCMs consistently show that anthropogenic influences had an important role in the extreme heat event over Korea, increasing the chance of the occurrence of extreme warming in summer mean temperature as observed in 2013 by at least 20 times, which supports results from the Coupled Model Intercomparison Project Phase 5 (CMIP5) coupled GCMs (CGCMs). A comparison of individual CMIP5 CGCMs suggests that inter-model difference in FAR values is highly correlated with the amplitude of surface warming centered over Korea, which is also supported by the three AGCMs. Further analysis of individual forcing experiments suggests that the inter-model difference in the regional surface warming is closely linked to the model's response to the aerosol forcing, with stronger influence than that of greenhouse gas forcing. Anthropogenic influences also result in a 5–6 times greater likelihood of extreme daily heat events as observed in 2013, which supports a robust mean-extreme relation in the attribution of extreme heat waves. Generally good agreement between AGCM and CGCM results increases the robustness of the conclusion of anthropogenic influences on the summer 2013 Korean heat wave.