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국제학술지

공지 (2025. 10. 28.)

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Emergence of autumn rainy season in Korea due to tropical cyclone influence

Abstract: Autumn in Korea, following the peak rainy season in summer, is of a great importance as it coincides with the intensive harvesting of crops and fruits. Hence, autumn rainfall critically affects agricultural production in Korea. This study shows the emergence of new rainfall peaks in autumn, leading to potentially significant agricultural damages. In the monthly period from September 10 to October 10, the total rainfall in the recent period (150 mm for 1998–2023) has increased by 44 mm compared to the previous period (106 mm for 1979–1997), averaged over 61 stations. Heavy rainfall days (≥ 100 mm day−1) have also occurred more frequently. The most plausible mechanism for these changes is the delayed retreat of the western North Pacific subtropical high in autumn which results in westward shift of tropical cyclone (TC) tracks and increased number of days on which Korea is affected by TCs. In addition, rising sea surface temperatures (0.5–1.0°C) in the western North Pacific and the South China Sea appear to be related to increased TC-induced heavy rainfall in Korea. Enhanced low-level moisture transports from these warm oceanic areas toward Korea, combined with upper-level wind divergence, are likely to have intensified the conditions for the TC-induced heavy rainfall. This study highlights the need for further research and public awareness of the changing autumn rainfall patterns and their impacts on agriculture and infrastructure. Available online 4 July 2025
- 작성자Kim et al.
- 작성일2025.10.28
- 조회수5
- 2026
Limitations of ENSO-based prediction of Korean winter temperature

Abstract: This study investigates the statistical and dynamical relationship between the El Niño-Southern Oscillation (ENSO) and winter surface air temperature (SAT) in Korea, using station observations and reanalysis data from 1920 to 2023. Historical SAT records are compiled from 7, 14, and 60 stations for 1920–1959, 1960–1972, and 1973–2023, respectively. Despite the statistically significant correlation (r = 0.28) between the Niño 3.4 index and winter SAT in Korea, ENSO alone explains only a limited amount of interannual variability. Classifying the SAT anomalies according to the ENSO phase (i.e., warm for El Niño and cold for La Niña), the Niño 3.4 index yields binary-classification accuracy of 0.68; however, about half of the correctly classified anomalies fall within ±0.5 standard deviations from the climatological mean. Also, composite circulation patterns based on ENSO phases differ structurally from those associated with actual SAT anomalies. A multiple linear regression analysis reveals that mid- to high-latitude climate variables, such as the East Asian winter monsoon, western North Pacific (WNP) sea surface temperatures (SSTs), and the Arctic Oscillation, exhibit stronger and more stable associations with Korean winter SAT than ENSO. Especially WNP SSTs show the largest standardized regression coefficients (> 5.0) to indicate their dominant role. This study suggests the need for integrated forecasting approaches that consider both the tropical and extratropical influences, rather than relying solely on ENSO signals for improving the accuracy of seasonal climate predictions and supporting adaptive risk management strategies for wintertime extremes in the Korean Peninsula.
- 작성자Yoo et al.
- 작성일2025.10.28
- 조회수9
- 2025
Microplastic transfer pathways in rural household environments through integrated compartmental analysis

Abstract: Microplastic (MP) pollution is a serious environmental and public health concern. However, the mechanisms governing MP distribution and transport in rural household environments remain poorly understood. This study presents the first integrated compartmental analysis of MP transfer between outdoor and indoor matrices, including soil, indoor air (inlet and outlet), and reused cooking oil in households located in Karunya Nagar (10.938523°N, 76.743782°E), a rural area in India. Samples were selected based on waste mismanagement profiles and analyzed using Fourier transform infrared spectroscopy. High plastic loads detected in the soil samples consisted of polypropylene (PP, 38.21%), polyethylene terephthalate (PET, 32.85%), polyethylene (22.78%), and polystyrene (PS, 6.16%), likely originating from agricultural films, packaging, and burned household waste. Samples from the air inlet predominantly contained PP (41.72%) and PET (33.94%), suggesting resuspension from contaminated soil due to wind action. Substantial concentrations of PET (42.4%) and PS (25.4%) were detected in reused indoor cooking oil, representing increases of 29.1% and 14.2%, respectively, relative to the air inlet samples. This suggested sorption and thermal transfer during cooking processes in open containers. Increases of 9.4% PP and 0.27% PET in air outlet profiles provided evidence of re-aerosolization during heating and inefficient ventilation. Polymer aging and oxidative degradation were confirmed by spectral intensities at 1783.1 cm−1, 1161.15 cm−1, and 509.21 cm−1. These results reveal a continuous, cyclic pathway of MP entry, accumulation, and secondary emission within rural households, demonstrating an overlooked but critical exposure route that necessitates targeted waste management and health interventions.
- 작성자Rakshith et al.
- 작성일2025.10.28
- 조회수5
- 2025
FTIR based assessment of MP contamination in soil water and insect ecosystems reveals environmental and ecological risks

Abstract: Microplastic (MP) pollution has emerged as a critical global environmental concern, impacting soil, water, and insect ecosystems. This study quantified MP prevalence in soil, water, and insect samples collected from specified rural and semi-urban study areas in the southern India, using Fourier-transform infrared (FTIR) spectroscopy for contamination assessment. The results revealed a predominance of polypropylene/polystyrene (PP/PS; 91.3%), followed by polyethylene (PE; 15.1%), polyethylene terephthalate (PET; 9.2%), and polyamide (PA; 6.2%). Insect samples showed high MP adherence, particularly in blister beetles, click beetles, and carpenter bees, suggesting their role as vectors for MP dissemination, mainly through adherence pathways. FTIR analysis confirmed characteristic MP absorption peaks at 1637.6 cm−1 (PP/PS), 1031.9 cm−1 (PE), 582.5 cm−1 (PET), and 3448.7 cm−1 (-OH groups), indicating interactions between MP and organic matter. FTIR analysis of soil samples showed PE as the dominant MP, with higher quantities in garbage sites (36.0%) and residential areas (34.9%) compared to agricultural farms (18.9%). Soil samples varied significantly, with bulk density (1.1–1.4 g cc−1), porosity (36.1–58.0%), and organic carbon content (0.7–1.9%), indicating potential impacts on fertility and microbial activity. Water samples from irrigation sources showed detectable PET (1.2%) and PA (0.7%) concentrations, with a distinct peak at 2316.5 cm−1, raising concerns about agricultural sustainability and food safety. These findings highlight the urgent need for stricter waste management regulations and further studies into the long-term environmental and human health risks of MP pollution. Full title: FTIR based assessment of microplastic contamination in soil water and insect ecosystems reveals environmental and ecological risks
- 작성자Rathikannu et al.
- 작성일2025.10.28
- 조회수6
- 2025
Arctic wildfire carbon emissions strongly influenced by midsummer Tibetan Plateau precipitation

Abstract: Wildfires in the Arctic are accelerating ecosystem damage and increasing global carbon emissions. Siberia, a major Arctic wildfire hotspot, is shaped by both local weather and distant climate influences. Here we use climate reanalysis data and numerical model experiments to show that summer wildfires in Siberia are strongly influenced by rainfall patterns over the Tibetan Plateau, one of the Northern Hemisphere’s largest summer heat sources. A dipole in Tibetan Plateau rainfall—wetter in the west, drier in the east—coincides with more fires in central Siberia and fewer in the east. This pattern alters high-altitude winds, shifting the jet stream northward and generating air flow changes that create favorable fire conditions across Siberia. Model experiments support a causal link. The resulting carbon dioxide emissions can match annual emissions from all Nordic countries. These findings highlight an overlooked driver of Arctic wildfires and improve our understanding of their role in the global carbon cycle.
- 작성자Yang et al.
- 작성일2025.10.28
- 조회수5
- 2025
Extratropical transition pathways of tropical cyclones and their role in storm intensity and destructiveness

Abstract: Tropical cyclones (TCs) undergoing extratropical transition (ET) can have widespread impacts; however, the differences in their evolutionary pathways remain incompletely understood. In this study, the cyclone phase space is applied to classify TCs in the western North Pacific from 1979 to 2022 into three distinct types. Type 1 exhibits the most pronounced asymmetry changes and retains the strongest surface winds, whereas Type 2 undergoes more modest asymmetry changes and maintains a weaker wind field. Type 3, in contrast, preserves a relatively symmetric wind field throughout the transition and occurs in a more baroclinic environment. Among the pathways, Type 1 demonstrates the highest post-transition destructiveness. Sensitivity analysis indicates that while most findings are robust across classification thresholds, Type 3 is particularly sensitive to threshold selection and requires careful interpretation. The present results enhance our understanding of ET variability and its implications for mid-latitude storm impacts.
- 작성자Cheung et al.
- 작성일2025.10.28
- 조회수6
- 2025
High PM2.5 episodes in Seoul, Korea, associated with Siberian High intensity

Abstract: The Siberian High (SH) dominates the wintertime atmospheric circulation over East Asia which strongly modulates the concentration of particulate matter ≤ 2.5 μm in diameter (PM2.5) in the region. While the SH exhibits considerable day-to-day variations, previous studies have focused on its seasonal and interannual effects rather than its short-term influence on PM2.5 concentrations. This study investigates the link between the evolution of atmospheric circulation associated with the changes in the SH intensity and the occurrence of high PM2.5 concentrations (≥ 35 µg m−3) in Seoul, Korea. Using a hierarchical clustering method, the synoptic patterns associated with 94 high-PM2.5 episodes in Seoul during the winters of 2008–2022 are classified into two groups based on the intensity of SH: 49 episodes with strong SH and 45 episodes with weak SH. Each SH pattern can induce high-PM2.5 episodes over distinct daily timescales through different dynamical and thermodynamical processes in the upper and lower troposphere. The strong SH is transformed into a migratory anticyclone over Korea, reducing wind speeds in the lower troposphere. These conditions suppress atmospheric ventilation and enhance dynamic stability, providing a favorable environment for rapid accumulation of PM2.5 near the surface within two days. During the weak SH events, the anticyclonic flow in the upper troposphere increases air temperatures in the mid-to-lower troposphere, resulting in increased low-tropospheric thermal stability. Air pollutants cannot disperse into the upper atmosphere and gradually accumulate to high PM2.5 levels over a period of four days. This study highlights that the development of atmospheric circulation in both strong and weak SH patterns plays an important role in the air quality degradation in Seoul through different temporal characteristics. These SH-driven atmospheric circulations provide valuable insights for improving forecast accuracy and enabling targeted emission control strategies based on the expected timing of pollution episodes.
- 작성자Kim et al.
- 작성일2025.10.28
- 조회수6
- 2025
Observational study of a quasi-stationary mesoscale convective system during extreme rainfall on 8 August 2022 in Korea

Abstract: On 8 August 2022, a quasi-stationary mesoscale convective system (MCS) produced prolonged extreme rainfall (> 100 mm h−1) over the Seoul metropolitan area, Republic of Korea. These organized convective systems, primarily composed of convective components with interspersed stratiform elements, are characterized by the successive local generations of convective cells. This study analyzes data from multiple observational platforms to understand the formation of the MCS and its microphysical evolution. The convective cells were initiated just off the west coast near Seoul, along the boundary between warm and cold air masses. Low-level convergence and favorable environmental conditions, including low lifting condensation level, level of free convection, and large convective available potential energy, facilitated the triggering of these cells. As the cells moved inland, they intensified rapidly due to the land-sea surface-friction contrast. Radar data show that as the MCS matured, reflectivity increased and the differential reflectivity decreased downward above the melting level, indicating the growth of ice crystals and graupels. The evolution of microphysical structure led to increases in both the mean diameter (Dm) and the number concentration (NT) of raindrops. This observation also suggests that the rainfall intensity was more closely related to the increase in NT than Dm during the period of heavy downpours. This study improves our understanding of the mesoscale processes related to extreme rainfall in Korea, critical for forecasting local heavy rainfall.
- 작성자Kim et al.
- 작성일2025.10.28
- 조회수6
- 2025
Recent changes in summer rainfall characteristics in Korea

Abstract: This study investigates the long-term variation in the summer rainfall characteristics in Korea by analysing the amount and intensity of rainfall and the number of rainy days at 57 stations for the June–September period from 1976 to 2023. For the primary rainy season, from 22 June to 1 August, the amount of rainfall in the post-2000 period is greater than that in the pre-2000 period, whereas the number of rainy days remains similar throughout the entire period. Rainfall intensity increases until 2000, then remains nearly unchanged after 2000. For the secondary rainy season, from 2 August to 10 September, both the rainfall amount and number of rainy days in the post-2000 period are larger than those in the pre-2000 period; however, the increase in rain intensity is less pronounced than that in the primary rainy season. These rainfall changes for the two rainy intra-seasons are found to be closely related to the increase in the frequency of heavy rainfall events (≥80 mm day−1), especially in the Seoul metropolitan area and the southern coastal regions. Previous studies have attributed the changes in the primary rainy season to the decrease (increase) in stationary fronts (convective rainfall), whereas the changes in all fronts (stationary and occluded) and the reduced influence of tropical cyclones in August have been identified as the main contributor in the secondary rainy season. This study improves our understanding of the recent changes in summer rainfall characteristics in Korea.
- 작성자Ho et al.
- 작성일2025.10.28
- 조회수3
- 2025
Interactions of the background state and eddies in shaping Aleutian Low variations

Abstract: The Aleutian Low (AL) is a dominant feature of the mean circulation in the North Pacific during the winter season. The background stationary wave, air-sea interaction, and transient eddies over the North Pacific exert distinct impacts on the interannual variations of the AL intensity and position. In this study, we adopt the quasi-geostrophic geopotential tendency equation to investigate the roles of various physical processes in the maintenance and interannual variations of this system. The results show that absolute vorticity advection plays the most important role in the formation and maintenance of AL intensity, while high-frequency transient eddies contribute most to the meridional and zonal shifts of the AL. The high-frequency transient eddy vorticity forcing affects the AL through the barotropic energy conversion process, and, in turn, the AL enhances the high-frequency transient eddies through the baroclinic energy conversion process, forming a positive feedback. The associated high-frequency eddy kinetic energy anomalies exhibit an eastward movement toward the east coast of North America in the years of an intensified AL, which explains why a strengthened AL is often accompanied by an eastward movement. Furthermore, the energy conversion terms of high-frequency transient eddies are mostly located over the extratropical eastern North Pacific, leading to asymmetric features in the zonal movement of the AL.
- 작성자Lin et al.
- 작성일2025.10.28
- 조회수7
- 2025
A dose-dependent bimodal switch by homologous Aux/IAA transcriptional repressors

Abstract: Combinatorial interactions between different regulators diversify and enrich the chance of transcriptional regulation in eukaryotic cells. However, a dose-dependent functional switch of homologous transcriptional repressors has rarely been reported. Here, we show that SHY2, an auxin/indole-3-acetic acid (Aux/IAA) repressor, exhibits a dose-dependent bimodal role in auxin-sensitive root-hair growth and gene transcription in Arabidopsis, whereas other Aux/IAA homologs consistently repress the auxin responses. The co-repressor (TOPLESS [TPL])-binding affinity of a bimodal Aux/IAA was lower than that of a consistently repressing Aux/IAA. The switch of a single amino acid residue in the TPL-binding motif between the bimodal form and the consistently repressing form switched their TPL-binding affinity and transcriptional and biological roles in auxin responses. Based on these data, we propose a model whereby competition between homologous repressors with different co-repressor-binding affinities could generate a bimodal output at the transcriptional and developmental levels.
- 작성자Cho et al.
- 작성일2025.10.28
- 조회수6
- 2024
Temporal pattern classification of PM2.5 chemical compositions in Seoul, Korea using K-means clustering analysis

Abstract: Particulate matter with a diameter ≤ 2.5 μm (PM2.5) is a complex mixture of particles with a variety of compositions potentially including sulfate ions (SO42−), nitrate ions (NO3−), ammonium ions (NH4+), organic and inorganic elemental carbon, and metals. Here, the temporal composition evolution of PM2.5 was analyzed to characterize its emission source, origin, and external influences. The concentrations of wintertime PM2.5 chemical compositions in Seoul, Korea during the period of 2012–2021 were classified into four representative clusters using a K-means cluster analysis method. Cluster 1 exhibited high concentrations of NO3− and NH4+ ions mainly due to the prevalence of emissions from domestic manure and fertilizer sources in the northeast. High concentrations of these two ions are conducive to generation of ammonium nitrate (NH4NO3) through atmospheric chemical reactions, resulting in relatively long-lasting high PM2.5 concentrations in Seoul. In cluster 2, high concentrations of SO42−, vanadium, and nickel were observed in frequent south-westerly winds, indicating the domestic influence of industrial facilities. Cluster 3 showed high concentrations of potassium ions and organic carbon, highlighting a pronounced external influence transported from China via prevailing westerly winds. Cluster 4 showed low PM2.5 concentrations accompanied by strong winds in warm environments, which are uncommon in winter. This study revealed that the air quality in Seoul, which was influenced by many factors, could be classified into four representative patterns. Our results provide insights into the emission sources, major influences, and responsible mechanisms of high PM2.5 concentrations in Seoul, which can help with air quality policies.
- 작성자Choi et al.
- 작성일2025.10.28
- 조회수7
- 2024
Synoptic circulation factors associated with wintertime high-PM2.5 in Seoul, ROK: Their interpretations and applications

Abstract: Many studies have explored atmospheric circulation fields associated with high particulate matter (PM) events, but only a few studies have evaluated the relative importance of meteorological variables in the circulation fields. In this study, we applied factor analysis method to examine meteorological variables related to the synoptic pattern of high-PM2.5 episodes (i.e., days with daily averaged PM2.5 concentration exceeding 35 μg m−3) in Seoul, Republic of Korea, during the winter season of 2004–2018. Here, we highlight three independent key factors (F1, F2, and F3) associated with high-PM2.5 concentrations. F1 is related to temperature (T) and meridional wind (V) at 850 hPa and 1000 hPa (i.e., T850, T1000, V850, and V1000) and temperature and geopotential height (Z) at 500 hPa (i.e., T500 and Z500). It is the most strongly correlated with T850, indicating an increase in thermal stability over Korea during high-PM2.5 events due to vertically reduced atmospheric ventilation. Meanwhile, F2 is significantly related to the geopotential height and zonal wind (U) at 850 hPa and 1000 hPa (i.e., Z850, Z1000, U850, and U1000). This indicates a dynamically stable condition due to the anomalous easterlies caused by the vertically elongated anticyclone over the northern part of the Korean Peninsula. Finally, F3 is positively associated with zonal and meridional winds at 500 hPa (i.e., U500 and V500). This means that relatively strong winds in the low-to-mid troposphere contribute to high-PM2.5 concentrations by transporting pollutants from the industrial regions of eastern China to Korea. We also examined the possible influence of climate change on high-PM2.5 concentrations based on the aforementioned three factors. According to the various shared socioeconomic pathway (SSP) scenarios, F1 increases significantly for all SSP scenarios compared to F2 and F3, indicating that synoptic patterns related to F1 occur frequently, leading to a favorable condition for high-PM2.5 concentrations. Thus, our finding suggests that climate change alone could worsen air quality in the future even without changes in direct PM2.5 emissions. Full title: Synoptic circulation factors associated with wintertime high-PM2.5 concentrations in Seoul, Republic of Korea: Their interpretations and applications
- 작성자Oh et al.
- 작성일2025.10.28
- 조회수6
- 2024
Development of a monthly PM2.5 forecast model for Seoul, Korea, based on the dynamic climate forecast and CNN algorithm

Abstract: A convolutional neural network (CNN) model has been developed to predict monthly concentrations of particulate matter with a diameter ≤ 2.5 μm (PM2.5) in Seoul, Republic of Korea, during winter months (November through February). Seven meteorological variables influencing PM2.5 concentrations were selected as predictors: geopotential heights at 1000 and 500 hPa, zonal and meridional winds, relative humidity and temperature at 850 hPa, and boundary layer height. These predictors were obtained from the fifth generation of the European Centre for Medium-Range Weather Forecasts reanalysis (ERA5) for model construction and from the Korea Polar Prediction System (KPOPS) dynamic forecasts for operational predictions. From the 11-year ERA5 dataset for 2008-2020, one year was allocated for testing, while the remaining 10 years were randomly assigned for either training (80%) or validation (20%). This process was repeated until all 11 years were allocated for testing, resulting in 11 CNN models. The benchmark which used the ERA5 dataset as the predictors yielded a mean bias error (MBE) of 0.05 μg m-3, root mean square error (RMSE) of 2.41 μg m-3, Pearson correlation coefficient (R) of 0.85, and 71% hit rate in predicting the months of high PM2.5 concentrations (≥ 30 μg m-3) for the testing periods. The 11-CNN-model ensemble predictions using the KPOPS forecasts resulted in an MBE of 0.1 μg m-3, RMSE of 3.19 μg m-3, R of 0.74, and hit rate of 62.5% for the period 2008-2020. Considering that the average temporal correlation coefficients between the ERA5 and the KPOPS forecasts for the seven predictors ranged from 0.20 to 0.66, the CNN-based PM2.5 prediction model has demonstrated good performance in overcoming the adverse effects of the KPOPS forecast errors on predicting PM2.5 concentrations. The CNN model showed limitations for unusual period such as the COVID-19 period, November 2020 through February 2022, when the emissions in East Asia were substantially below their climatological normal levels. In conclusion, the CNN model developed in this study showed potential applicability to operational monthly PM2.5 concentration predictions for the years of normal emissions using solely meteorological data. This can provide professionals in various fields, such as health care and environmental science, with valuable insights for long-term planning. Full title: Development of a monthly PM2.5 forecast model for Seoul, Korea, based on the dynamic climate forecast and a convolutional neural network algorithm
- 작성자Park et al.
- 작성일2024.08.22
- 조회수171
- 2024
Modulations of MJO and QBWO on early summer tropical cyclone genesis over Bay of Bengal and South China Sea

Abstract: The Madden–Julian oscillation (MJO) and the quasi-biweekly oscillation (QBWO) are prominent components of the intraseasonal oscillations over the tropical Indo-Pacific Ocean. This study examines the tropical cyclone (TC) genesis over the Bay of Bengal (BOB) and the South China Sea (SCS) on an intraseasonal scale in May–June during 1979–2021. Results show that the convection associated with the two types of intraseasonal oscillations simultaneously modulates TC genesis in both ocean basins. As the MJO/QBWO convection propagated, TCs form alternately over the two basins, with a significant increase (decrease) in TC genesis frequency in the convective (nonconvective) MJO/QBWO phase. Based on the anomalous genesis potential index associated with the MJO/QBWO, an assessment of the influence of various factors on TC genesis is further assessed. Middle-level relative humidity and lower-level relative vorticity play key roles in the MJO/QBWO modulation on TC genesis. The MJO primarily enhances large-scale cross-equatorial moisture transport, resulting in significant moisture convergence, while the QBWO generally strengthens the monsoon trough and induces the retreat of the western North Pacific subtropical high, increasing the regional lower-level relative vorticity. The potential intensity and vertical wind shear make small or negative contributions. This study provides insights into the neighboring basin TC relationship at intraseasonal scales, which has a potential to improve the short-term prediction of regional TC activity. Full title: Modulations of Madden-Julian oscillation and quasi-biweekly oscillation on early summer tropical cyclone genesis over Bay of Bengal and South China Sea
- 작성자Chen et al.
- 작성일2024.08.22
- 조회수97
- 2024
Geostationary satellite-derived positioning of a TC center using artificial intelligence algorithms over the WNP

Abstract: Artificial intelligence (AI) models were developed to determine the center of tropical cyclones (TCs) in the western North Pacific. These models integrated information from six channels of geostationary satellite imagery: the brightness temperature of four infrared (IR) and one shortwave IR channels, as well as the reflectivity of one visible channel. The first model is a convolutional neural network designed for spatial data processing, and the second is a convolutional long short-term memory model that effectively captures spatiotemporal information. For training, verification, and testing purposes, spatial images from six channels were obtained from the Japanese Himawari-8 satellite from 2016 to 2021. The position of the European Centre for Medium-Range Weather Forecasts 6- or 12-h prediction was assigned as an initial value to the AI models. Errors in the initial value were 20–50 km compared to the Joint Typhoon Warning Center best track, depending on TC intensity. Weak (strong) TCs exhibited large (small) errors. This error dependency was found in Automated Rotational Center Hurricane Eye Retrieval (ARCHER) product, which is currently used by several operational organizations. ARCHER errors were typically small when observations from both geostationary and polar-orbiting satellites were included. Significant errors remained in the absence of microwave channel information from polar-orbiting satellites. This study successfully developed two AI models that consistently determined the location of the TC center using only six-channel images from geostationary satellites. These models exhibited comparable or better performance than the ARCHER products. The newly developed AI models can potentially be implemented for operational use. Full title: Geostationary satellite-derived positioning of a tropical cyclone center using artificial intelligence algorithms over the western North Pacific
- 작성자Ho et al.
- 작성일2024.06.13
- 조회수139
- 2024
Development of interpretable probability ellipse in TC track forecasts using multiple operational EPSs

Abstract: Most tropical cyclone (TC) forecasting centers have implemented a probabilistic circle to represent track uncertainty at a specified lead time. Recent studies suggest that probability ellipses constructed from ensemble prediction systems can convey the anisotropy of track predictability. In this study, a new probability ellipse model is developed to interpret the extent of forward speed and heading uncertainties in ensemble forecasts by selecting an equal proportion of members in the along- and cross-track directions. This method is validated using the 2019–2021 western North Pacific (WNP) TC track forecasts from the ensemble predictions of the European Centre for Medium-Range Weather Forecasts, the United States National Centers for Environmental Prediction, and the Korea Meteorological Administration. When the proportion of ensemble members in the ellipse is set to 70%, more than one-half (50.0%–73.6%) of the forecasts, depending on the lead time, indicate reduced area compared with that of the circle. The mean areas of the probability ellipses are 4.9%, 7.0%, 10.0%, and 11.5% smaller than those of the circle in 48-, 72-, 96-, and 120-hr forecasts, respectively. The forward speed shows greater uncertainty than the heading, as evidenced by the along-track radii being larger than the cross-track counterpart in ∼60% of the samples, regardless of the lead time. In addition, the regional distribution of the along-track/cross-track ratio in the probability ellipses can explain the dominant direction of the track error in a particular location. The proposed probability ellipse shows potential for application in operational TC track predictions. Full title: Development of interpretable probability ellipse in tropical cyclone track forecasts using multiple operational ensemble prediction systems
- 작성자Yoo and Ho
- 작성일2024.06.13
- 조회수276
- 2024
Sea surface temperature warming to inhibit mitigation of tropical cyclone destructiveness over East Asia in El Niño

Abstract: Given their conditions to reside in and intensify longer over warm oceans, tropical cyclones (TCs) in the western North Pacific (WNP) present a stronger lifetime maximum intensity during El Niño than during La Niña. By using observational data, we found that the anomalously cool sea surface temperature (SST)s in the basin act as effective barriers against intense TCs approaching East Asia during El Niño, weakening their destructiveness at landfall. Based on our high-resolution pseudo-global-warming simulations, the basin-wide 2K SST warming within the WNP basin can, however, shatter this cool SST barrier, exposing East Asia to more destructive TCs during El Niño, compared to those during La Niña. Considering that the 2K warmer WNP will likely occur in the mid-21st century under a high emission scenario and in the late 21st century under a moderate emission scenario, our findings support that more aggressive efforts of global warming mitigation are needed.
- 작성자Park et al.
- 작성일2024.08.22
- 조회수102
- 2024
Polarimetric radar signatures in various lightning activities during Seoul (Korea) flood on August 8, 2022

Abstract: On August 8 and 9, 2022, a record-breaking rain rate of 142 mm h-1, with an accumulated rainfall of more than 500 mm, was observed in the Seoul metropolitan area, Republic of Korea. This study focuses on analyzing the concentration of lightning in southern Seoul, which occurred solely on August 8. It is worth noting that the daily rainfall of August 8 was approximately twice that of August 9 (381 mm on August 8 vs. 198 mm on August 9). The RKSG (located in Yongin, 40 km south of Seoul) Weather Surveillance Radar-1988 Doppler was used to explore the characteristics of cloud microphysics associated with lightning activity. Four major heavy rain periods on August 8 were grouped into three categories of lightning rate (e.g., intense, moderate, and none), and their polarimetric signatures were compared. Significant differences in the vertical distribution of graupel were found within the temperature range of 0 °C and − 20 °C, as indicated by radar reflectivity (ZH) > 40 dBZ and differential reflectivity (ZDR) < 0.5 dB. Although graupel was detected in all three categories at the relatively warm temperatures of 0 °C to − 10 °C, its presence extended into colder regions exclusively in the intense category. This observation preceded the appearance of lightning by approximately 6 min. At heights with temperature ≤ − 20 °C, a high concentration of vertically aligned ice crystals was observed in lightning-prone regions, leading to a decrease in differential phase (ΦDP). In summary, this study provides valuable insights into the microphysical characteristics of thunderstorms and their relationship to lightning activity in the Seoul metropolitan area.
- 작성자Kim et al.
- 작성일2024.08.22
- 조회수94
- 2024
Centennial analysis in tropical cyclone induced precipitation in Korea

Abstract: Tropical cyclone (TC)-induced precipitation has undergone significant multidecadal changes over the last 117 years (1904–2020) on the Korean Peninsula, as determined through the analysis of affected TCs and surface-observed precipitation at ten stations in the Republic of Korea (hereafter Korea). Information on TCs that have affected Korea over a century was collected from the National Typhoon Center of the Korea Meteorological Administration (KMA). The information was cross-validated by referring to the International Best Track Archive for Climate Stewardship archive, while the information for 1904–1950 was cross-validated by also examining extreme weather reports in newspapers. A significant regime shift in the annual total heavy rainfall (confined to rain events ≥100 mm day−1), and its frequency associated with the affected TCs was found before and after 1979. The regime-shift signal is robust regardless of the methodology. Heavy rainfall from non-TC events, however, has presented a regime-shift increase since 1997. Based on a detailed review of historical documents describing instrument type, measuring method, altitude, and site location, this rainfall increase in regime-shift is likely a non-climatic signal coming from updates in measurement tools (i.e., the weather station automation project of KMA) during 1995–2000. However, increases in heavy rainfall of TC events in 1979 are comprehensively supported by the intensity and track changes in Korea affecting TC and changes in large-scale atmospheric and oceanic environments. The present results provide an earnest validation of TC records over the Korean Peninsula and confirm a regime-shift increase in TC hazards over Korea, thus providing grounds for further global analysis.
- 작성자Chang et al.
- 작성일2024.09.04
- 조회수112
- 2023