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국제학술지

공지 (2025. 10. 28.)

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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
- 조회수8
- 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
- 조회수10
- 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
- 조회수10
- 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
- 조회수174
- 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
- 조회수98
- 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
- 조회수141
- 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
- 조회수278
- 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
- 조회수105
- 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
- 조회수97
- 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
- 조회수114
- 2023
Critical contribution of moisture to the air quality deterioration in a warm and humid weather

Abstract: The deterioration of air quality that threatens human health is recognized as focal compound hazard. Here, decisive thermodynamic conditions for activation of secondary aerosol formation have been investigated focused on Korea. In a dry environment with relative humidity < 60%, gas phase reaction to form fine particles depended largely on surface temperature. In a wet environment (relative humidity ≥ 60%), however, aqueous phase reaction of secondary inorganic aerosols, which are sulfate, nitrate, and ammonium, accounting for 67% of the total aerosol mass, was more activated. Thus, humidity is as important as temperature in the secondary production of aerosol; air quality often worsened when a low-pressure system was predominant over the Korean Peninsula. It is rather different from the general synoptic conditions of high concentrations of particulate matters characterized by high pressure and atmospheric stagnation. This study suggests additional favorable condition and responsible mechanism of air quality hazards that may be frequent in future.
- 작성자Choi et al.
- 작성일2024.09.04
- 조회수96
- 2023
Ineffective implementation of emergency reduction measures against high concentrations of particulate matter in Seoul...

Abstract: Since December 30, 2017, the Seoul Metropolitan Government, Republic of Korea, has been implementing emergency reduction measures (ERMs) restricting the operation of industrial sites, thermal power plants, and vehicles when air quality is expected to deteriorate. ERMs are implemented when the present observed concentration of particulate matter (PM) of aerodynamic diameter less than 2.5 μm (PM2.5) and/or the predicted values for the following day exceed a threshold value. In this study, the effectiveness of ERMs was evaluated for 33 days with and 6 days without ERM implementation but where the PM2.5 concentration exceeded the threshold value, until March 15, 2021. Of the 33 days of ERM implementation, on 7 days it was executed despite the thresholds not being met. The ERM on these days might have been properly executed because the pre-notice and implementation of ERM might have reduced the local emissions of air pollutants. Our major findings are that even on days of ERM implementation, there were marginal reductions in vehicle traffic, thermal power generation, and industrial emissions. Second, the concentrations of PM2.5 and related air pollutants in Seoul were almost unchanged for most ERM implementation episodes. Third, most of the 39 (= 33 + 6) days when the air quality worsened were caused by the transboundary transport of air pollutants from China. In conclusion, it was revealed that the currently executed ERM law is insufficient for effectively reducing PM2.5. To achieve the required reductions, it is necessary to undertake stricter policies in Seoul and its neighboring regions. Full title: Ineffective implementation of emergency reduction measures against high concentrations of particulate matter in Seoul, Republic of Korea
- 작성자Ho and Kim
- 작성일2024.09.04
- 조회수82
- 2023
Major decisive factors of tropical cyclone risk in the Republic of Korea: Intensity, track, and extratropical transition

Abstract: After the catastrophic damage caused by the extratropical transitioned North Atlantic hurricane Sandy (2012), the decaying stage of a tropical cyclone (TC) have received more attention. TC undergoing extratropical transition (ET) in mid-latitudes may become hazardous with torrential rain and violent wind over a vast area. In this study, a decision tree analysis was applied to evaluate the relative importance of TC parameters such as intensity category, entry location, and distance from coastlines, in determining damage occurrence. All 123 landfalling TCs in the Republic of Korea (hereafter Korea) during 1979–2015 were analyzed. The results reveal that intense TCs (severe tropical storms and typhoons) incur damages regardless of entry location and distance from coastlines. TCs with tropical storm intensity are expected to incur damages only when they approach the southwest of the Korean Peninsula. Weak TC with maximum wind speeds smaller than 17 m s−1 does not have the potential to incur damages unless the TC was undergoing extratropical transition (ET) during landfall in Korea. ET storms that make a landfall approaching 1.22° (~130 km) to the coastline cause substantial damages especially in the west coast and capital area of Korea. The present results suggest that accurate forecasting that also considers ET, and not only intensity and track, is essential for successful disaster risk mitigation.
- 작성자Nam et al.
- 작성일2024.09.04
- 조회수54
- 2023
PM2.5 forecast in Korea using the long short-term memory (LSTM) model

Abstract: The National Institute of Environmental Research, under the Ministry of Environment of Korea, provides two-day forecasts, through AirKorea, of the concentration of particulate matter with diameters of ≤ 2.5 μm (PM2.5) in terms of four grades (low, moderate, high, and very high) over 19 districts nationwide. Particulate grades are subjectively designated by human forecasters based on forecast results from the Community Multiscale Air Quality (CMAQ) and artificial intelligence (AI) models in conjunction with weather patterns. This study evaluates forecasts from the long short-term memory (LSTM) algorithm relative to those from CMAQ-solely and AirKorea using observations from 2019. The skills of the one-day PM2.5 forecasts over the 19 districts were 39–70% for CMAQ, 72–79% for LSTM, and 73–80% for AirKorea; the AI forecasts showed comparable skills to the human forecasters at AirKorea. The one-day forecast skill levels of high and very high PM2.5 pollution grades are 31–98%, 31–74%, and 39–81% for the CMAQ-solely, the LSTM, and the AirKorea forecasts, respectively. Despite good skills for forecasting the high and very high events, CMAQ-solely forecasts also generate substantially higher false alarm rates (up to 86%) than the LSTM and AirKorea forecasts (up to 58%). Hence, applying only the LSTM model to the CMAQ forecasts can yield reasonable forecast skill levels comparable to the operational AirKorea forecasts that elaborately combine the CMAQ model, AI models, and human forecasters. The present results suggest that applications of appropriate AI models can greatly enhance PM2.5 forecast skills for Korea in a more objective way.
- 작성자Ho et al.
- 작성일2024.09.04
- 조회수122
- 2023
Rainfall strength and area from landfalling TCs over the North Indian and WNP oceans under increased CO2 conditions

Abstract: Climate change due to greenhouse gases has fueled more intense tropical cyclones (TCs) globally. However, the characteristics rainfall strength (RS) and rainfall area (RA) of TCs and their future changes in regional scales are not yet fully understood. Here, using ultra-high-resolution coupled model simulations, we investigate the dominant factors which control rainfall characteristics of landfalling TCs in the North Indian Ocean (NIO) and western-North Pacific (WNP) and their future change in responses to doubling and quadrupling of atmospheric CO2 concentrations. In the NIO, RS increases more than RA when CO2 rises, but the WNP shows the opposite behavior. We demonstrate that RS is highly related to the lifetime maximum intensity, landfall intensity, and latent heat flux (LHFLX), while RA depends mainly on LHFLX, relative humidity at 600 hPa, and vertical wind shear over the WNP. Our results suggest the need to establish regional-scale adaptation strategies for future changes in landfalling TCs rainfall. Full title: Rainfall strength and area from landfalling tropical cyclones over the North Indian and western North Pacific oceans under increased CO₂ conditions
- 작성자Moon et al.
- 작성일2024.09.04
- 조회수73
- 2023
Recent air quality deterioration on weekends in Seoul, South Korea: A focus on external contribution

Abstract: This study has found that the wintertime (November–March) air quality in Seoul, Korea had been deteriorated in weekends during the period of 2016–2019. Specifically, the concentration of particulate matters (PMs) of aerodynamic diameter less than 2.5 μm (PM2.5) in weekends (Saturday–Sunday) was up to 30% higher than that in the mid-week (Wednesday–Thursday) days (probability value < 0.01). As the weekend PM concentration had been lower than the mid-week values by 10% until 2015, such a sudden change in the intra-weekly air quality is unexpected. This study finds out that the deterioration of air quality in weekends can be attributed primarily to secondary particle formations and external transports from China (Shandong and northeast provinces) and domestic provinces (southern Gyeonggi and Chungcheong in Korea) to Seoul. High concentration of PM2.5 on weekend could be partially explained by the differences in the concentrations of inorganic PM components including nitrate, ammonium, and sulfate between weekends and mid-week days. About 40% of the differences are attributed to the domestic sources located in the southern region to Seoul. However, domestic emission from power generations and industry sector in southern source region on weekends does not well explain the variations of the PM precursors in weekends. Therefore, a clear strategy for improving air quality on the weekend in Seoul requires steady efforts to accurately calculate regional emissions and to reveal missing emissions sources.
- 작성자Choi et al.
- 작성일2024.09.04
- 조회수62
- 2023
Enhanced seasonal amplitude of atmospheric CO2 by the Southern Ocean

Abstract: The enhanced seasonal amplitude of atmospheric CO2 has been viewed so far primarily as a Northern Hemisphere phenomenon. Yet, analyses of atmospheric CO2 records from 49 stations between 1980 and 2018 reveal substantial trends and variations in this amplitude globally. While no significant trends can be discerned before 2000 in most places, strong positive trends emerge after 2000 in the southern high latitudes. Using factorial simulations with an atmospheric transport model and analyses of surface ocean PCO2 observations, we show that the increase is best explained by the onset of increasing seasonality of air-sea CO2 exchange over the Southern Ocean around 2000. Underlying these changes is the long-term ocean acidification trend that tends to enhance the seasonality of the air-sea fluxes, but this trend is modified by the decadal variability of the Southern Ocean carbon sink. The seasonal variations of atmospheric CO2 thus emerge as a sensitive recorder of the variations of the Southern Ocean carbon sink.
- 작성자Yun et al.
- 작성일2024.09.04
- 조회수66
- 2022
Erratic Asian summer monsoon 2020: COVID-19 lockdown initiatives possible cause for these episodes?

Abstract: The summer (June through September) monsoon 2020 has been very erratic with episodes of heavy and devastating rains, landslides and catastrophic winds over South Asia (India, Pakistan, Nepal, Bangladesh), East Asia (China, Korea, and Japan), and Southeast Asia (Singapore, Thailand, Vietnam, Laos, Cambodia, Philippines, Indonesia). The withdrawal of the summer monsoon over India was delayed by 2 weeks. The monsoon season over East Asia has been the longest. China recorded a Dam burst in the twentieth century. Furthermore, the Korean Peninsula has experienced back-to-back severe tropical cyclones. Could the lockdown activities initiate to control the COVID-19 spread a possible cause for these major episodes? The strict enforcement of the lockdown regulations has led to a considerable reduction of air pollutants—dust and aerosols throughout the world. A recent study based on satellites and merged products has documented a statistically significant mean reduction of about 20, 8, and 50% in nitrogen dioxide, Aerosol Optical Depth (AOD) and PM2.5 concentrations, respectively over the megacities across the globe. Our analysis reveals a considerable reduction of about 20% in AOD over South as well as over East Asia, more-over East Asia than over South Asia. The reduced aerosols have impacted the strength of the incoming solar radiation as evidenced by enhanced warming, more-over the land than the oceans. The differential warming over the land and the ocean has resulted in the amplification of the meridional ocean-land thermal contrast and strengthening of the monsoon flow. These intense features have supported the surplus transport of moisture from the oceans towards the main lands. Some similarity between the anomalous rainfall pattern and the anomalous AOD pattern is discernable. In particular, the enhancement of rainfall, the reduction in AOD and the surface temperature warming match very well over two regions one over West-Central India and the other over the Yangzte River Valley. Results further reveal that the heavy rains over the Yangzte River Valley could be associated with the preceding reduced aerosols, while the heavy rains over West-Central India could be associated with reduced aerosols and also due to the surface temperature warming.
- 작성자Kripalani et al.
- 작성일2024.09.04
- 조회수65
- 2022
Latitudinal variation of the lifetime maximum intensity location of Atlantic tropical cyclones controlled by the AMO

Abstract: The latitude of lifetime maximum intensity (LMI) location (ϕLMI) of Atlantic tropical cyclones (TCs) is related to the Atlantic Multidecadal Oscillation (AMO) with a significant negative correlation for 1948–2018. We objectively classify TC tracks into four patterns, to evaluate the effects of variations in dominant track patterns (track ϕLMI) and intra-pattern ϕLMI (pure ϕLMI) on the total ϕLMI variation. During the warm phases of AMO, the prevailed south-origin track patterns and equatorward pure ϕLMI shifts have almost equally contributed to the equatorward migration of the total ϕLMI. The negative anomaly of potential intensity in the subtropics is responsible for the equatorward shift of pure ϕLMI. Moreover, weak vertical wind shear in the tropics increases the south-origin track patterns. These environmental conditions are associated with the east-strong and west-weak relative sea surface temperature warming during the warm phases that causes anomalous upward and downward motions in the eastern and western Atlantic, respectively. Full title: Latitudinal variation of the lifetime maximum intensity location of Atlantic tropical cyclones controlled by the Atlantic Multidecadal Oscillation
- 작성자Kim et al.
- 작성일2024.09.04
- 조회수66
- 2022
Possible influence of ENSO Modoki and AO on spatiotemporal variability of spring precipitation over the WNP

Abstract: There are two leading modes in boreal spring precipitation over the western North Pacific (WNP). The first leading mode is a dipole pattern between the southern China and Southeast Asia, which have been previously investigated. The second leading mode is a tripole pattern, which this study focused on. The pattern shows that the positive cores are located in the midlatitudes and the tropical WNP, respectively, whereas the negative one extends from the subtropics to the South China Sea. The mode of tripole pattern is predominantly responsible for the actual spring precipitation variation in the subtropics (r = − 0.93). On the other hand, the precipitation variations in the midlatitudes, the tropical WNP, and the South China Sea are not well explained as much as that in the subtropics. The tripole-pattern-related circulation resembles the positive phase of North Pacific Oscillation, possibly associated with the El Niño Modoki and the positive phase of Arctic Oscillation. The circulation corresponds to the northward shift of the WNP subtropical high, which contributes to the precipitation increase and decrease in the midlatitudes and subtropics, respectively. Meanwhile, the weakened Walker circulation in tropical western Pacific accounts for the decreased and the increased precipitation in the South China Sea and the tropical WNP, respectively. The opposite is true for the circulations related to the La Niña Modoki and negative phase of Arctic Oscillation. Full title: Possible influence of ENSO Modoki and Arctic Oscillation on spatiotemporal variability of spring precipitation over the western North Pacific
- 작성자Park et al.
- 작성일2024.09.04
- 조회수62
- 2022