국제학술지 게시판목록 | 이화여자대학교 기후물리실험실

Publications

국제학술지

공지 (2025. 10. 28.)

현재까지 출판된 논문 목록입니다. 아직 준비 중인 논문은 포함하지 않은 점 참고 바랍니다.

Roles of meteorological factors in inter-regional variations of fine and coarse PM concentrations over the ROK

Abstract: This study examined meteorological effects on airborne concentrations of particulate matter (PM) of 25% of PM2.5 variability can be explained by Random Forest regression with only atmospheric variables, compared to little accountability for PM2.5–10. The two most important variables that affect PM2.5 variability are surface air temperature and wind. Transboundary transport controlled by atmospheric factors causes fine PM from northeast and east China to affect PM2.5 variations a day after emissions in the northern-central and southern regions of Korea, respectively; and coarse PM from east China affects PM2.5–10 variations in Korea on the same day. The present results suggest that local governments of regions with high PM concentrations should strengthen regulation policies with a long-term perspective, considering future changes in atmospheric conditions that may cause increases in PM levels. Full title: Roles of meteorological factors in inter-regional variations of fine and coarse PM concentrations over the Republic of Korea
- 작성자Lee et al.
- 작성일2024.09.04
- 조회수79
- 2021
Synoptic conditions controlling the seasonal onset and days of heatwaves over Korea

Abstract: As global warming gets worse, the extreme heat exposure time is expected to increase. Considering that the heatwave damages increased by the accumulation of heat stress, it is important to understand the heatwave onset and number of heatwave days (HWDs). Here, we show that the end of East Asian summer monsoon activity (i.e., Changma retreat date, CRD) could be an indicator in determining the onset of the heatwave, and the barotropic structure induced by the circumglobal and Pacific–Japan teleconnections is a key factor in lengthening the number of HWDs in Korea. The onset of the heatwave is delayed when CRD belated than the climatology late over Korea due to sufficient moisture transportation between the edge of western North Pacific subtropical high and cold polar air mass in July. The number of HWDs from July through August over Korea shows a positive linear relationship with the synoptic stagnation index because the upper-layer anticyclone associated with stagnation is formed around Korea by zonal wave activity. Barotropic anticyclone stabilizes the atmosphere and increases the number of clear sky days, which possibly leads to hot days. Fewer HWDs are observed when there is baroclinic instability due to strong upper-level jet stream and synoptic-scale weather systems move smoothly. By identifying the meteorological mechanism of heatwave occurrence and favorable conditions for sustained hot days over Korea, our results are eventually able to contribute to reducing damages caused by heatwaves.
- 작성자Choi et al.
- 작성일2024.09.04
- 조회수64
- 2021
Systematic bias of WRF-CMAQ PM10 simulations for Seoul, Korea

Abstract: For evaluating the performance of the Korean operational air quality model (Weather Research and Forecasting-Community Multiscale Air Quality), we compared the simulated concentrations of particulate matter with diameters ≤ 10 μm (PM10) against observations in Seoul, Korea for the cold seasons (October through March) of 2015–2018. The simulations yield about 70% hit rate for PM10 concentrations within 10 μg m−3 from the observations. For the 50–90 μg m−3 range, the simulations systematically overestimate the PM10 frequency mainly due to overestimation/underestimation of PM10 concentrations in the moderate-PM10 (30 < PM10 ≤ 60 μg m−3)/high-PM10 (60 < PM10 ≤ 100 μg m−3) range. Considering that the model simulates PM10 transports using input meteorological fields and emissions amounts, 72-h back-trajectories from Seoul (37.51°N, 126.99°E) at the 500 m above ground level are analyzed to investigate the cause of the systematic bias. The 410 days when PM10 concentrations are within the 30–100 μg m−3 range are grouped into three major wind flows: westerly (163 days), northerly (99 days), and northwesterly (148 days). Overestimations of moderate-PM10 days frequently occur for the westerly group associated with a synoptic pattern characterized by calm anticyclonic systems over China and Korea, especially when the emission amounts were overestimated in eastern China, the main PM10 source region for Seoul for the westerly group. Underestimations of high-PM10 days frequently occur for the northerly and northwesterly groups associated with climatological patterns or strong windy cyclonic systems along with some small inflow from underestimated emission in northeastern China. To improve the model performance, statistical models trained for each back-trajectory group along with improved estimations of emission amounts may prove helpful.
- 작성자Hur et al.
- 작성일2024.09.04
- 조회수75
- 2021
Two types of diurnal variations in heavy rainfall during July over Korea

Abstract: This study examined the characteristics of the diurnal variations of heavy rainfall (⩾110 mm in 12 hours) in Korea and the related atmospheric circulation for July from 1980–2020. During the analysis period, two dominant pattens of diurnal variation of the heavy rainfall emerged: all-day heavy rainfall (AD) and morning only heavy rainfall (MO) types. For the AD-type, the heavy rainfall is caused by abundant moisture content in conjunction with active convection in the morning (0000–1200, LST; LST = UTC + 9) and the afternoon hours (1200–2400 LST). These systems are related to the enhanced moisture inflow and upward motion induced by the strengthening of the western North Pacific subtropical high and upper-tropospheric jet. For the MO-type, heavy rainfall occurs mostly in the morning hours; the associated atmospheric patterns are similar to the climatology. We find that the atmospheric pattern related to severe heavy rainfalls in 2020 corresponds to a typical AD-type and resembles the 1991 heavy-rainfall system in its overall synoptic/mesoscale circulations. The present results imply that extremely heavy rainfall episodes in Korea during the 2020 summer may occur again in the future associated with the recurring atmospheric phenomenon related to the heavy rainfall.
- 작성자Park et al.
- 작성일2024.09.04
- 조회수83
- 2021
What caused the extraordinarily hot 2018 summer in Korea?

Abstract: In 2018, heatwaves (HWs), defined as a period of abnormally hot weather with a daily maximum temperature (T_Max) exceeding its 95th percentile threshold for at least 3 consecutive days, were prevalent from June through August, and temperature records exceeded the reference values in many countries over East Asia (EA), including China (CH), Japan (JP), and the Korean Peninsula (KP). Particularly, extreme HWs from July through August lasted for the longest duration of 21.3 days, with T_Max reaching 36.9°C. The highest T_Max recorded since 1907 was 41°C in Hongcheon, located east of Seoul in the KP. Here, we examined the factors that influenced the 2018 HW, and how these relate to the 1994 HW, which was the second longest HW recorded in the KP. The results showed that abnormally strong and northwestward extended anticyclone features observed in July 2018 lasted as a persistent North Pacific anticyclone anomaly until August 2018, centered at the northern KP. These anticyclone features subsequently formed a modon-like blocking, with a cyclonic anomaly in the East China Sea. In August 1994, the North Pacific High (NPH) extended to eastern EA, which broke down the meridional dipole structure and HWs did not persist. The NPH, which persisted until August 2018, was accompanied by a sinking motion, suppression of precipitation, anomalous maximum temperature, weakening of the westerly jet stream, and increased insolation due to clear sky. We found that the prolonged and northwestward-shifted NPH, including the KP, drove the extraordinarily hot 2018 summer in Korea. In addition, low precipitation and massive evapotranspiration with persistent insolation in July 2018 influenced the dry condition at the surface. We suggest that the predictions for the location and duration of the NPH associated with the HWs are required to reduce heat-related mortality and the impact on agriculture because of excessive evapotranspiration.
- 작성자Ha et al.
- 작성일2024.08.22
- 조회수101
- 2020
Simulations of winter Arctic clouds and associated radiation fluxes using different cloud microphysics schemes in the...

Abstract: Arctic cloud simulations of the polar-optimized version of the Weather Research and Forecasting model (Polar WRF) were compared with retrievals using the CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation measurements. For the period from 1 December 2015 to 31 January 2016, a series of 24- to 48-hr simulations initialized daily at 00 UTC were examined. In particular, two cloud microphysics schemes, the Morrison double moment and the WRF single-moment 6-class (WSM6), were tested. The modeled cloud top heights had a correlation coefficient (r) of 0.69–0.72 with those from satellite retrievals, and a mean bias of less than 400 m. For the mean ice water content profile and mixed-phase cloud occurrence, the Morrison scheme's clouds were in better agreement with satellite retrievals than the WSM6. However, the use of the Morrison scheme resulted in underestimates of outgoing longwave radiation by −11.7 W m-2 compared to satellite observations. The bias was reduced to −0.4 W m-2 with the WSM6 which produced a stronger precipitation rate (by 10%) resulting in a drier and less-cloudy atmosphere. This also leads to the 7-W m-2 mean difference in the surface downward longwave radiation (DLR) between the schemes, which is large enough to explain the spread of the Arctic DLR in the current climate models. However, as the temporal variation in DLR showed good agreement with ground observations (r: 0.68–0.92), it is concluded that the Polar WRF can be useful for studying cloud effects on the winter Arctic surface climate. Full title: Simulations of winter Arctic clouds and associated radiation fluxes using different cloud microphysics schemes in the Polar WRF: Comparisons with CloudSat, CALIPSO, and CERES
- 작성자Cho et al.
- 작성일2024.08.22
- 조회수68
- 2020
Projections of future drought intensity associated with various local greenhouse gas emission scenarios in East Asia

Abstract: Efforts to reduce greenhouse gas emissions are ongoing in many East Asian countries; however, their influences on future drought remain unknown. We analyzed future changes in drought intensity over East Asia using the Representative Concen tration Pathway (RCP) 8.5 and the new two limiting local greenhouse gas emission scenarios in East Asia: National Institute of Environmental Research (NIER)-H sce nario for high emission and NIER-L scenario for low emission. The two scenarios were made by a fully coupled global climate model with prescribed gas boundaries of high and low greenhouse gas emissions from an atmospheric chemistry model re flecting the up-to-date environmental policies of South Korea, China, and Japan. The application of a clustering analysis to the calculated drought index time series identi fied four zonally distributed drought regions in the present-day period (1951–2016). Among these regions, higher latitude regions showed a more rapidly increasing trend in drought intensity than other regions for the present-day period. All future scenarios projected the continuation of this meridional intensification trend of drought until 2100; however, the intensification rates in the NIER-L were much smaller than those in the RCP8.5 and NIER-H scenarios. Our results suggest that reducing greenhouse gas emissions is critical for East Asian countries to alleviate the potential damages of future droughts.
- 작성자Park et al.
- 작성일2024.08.22
- 조회수59
- 2020
Interannual variations of spring drought-prone conditions over three subregions of East Asia and associated...

Abstract: For proactive prevention of water shortage problems, it is important to understand the spatiotemporal variabilities of droughts and their development mechanisms. This study identified an interannual variation of spring drought-prone condition in each region of East Asia (EA)—northern, mid, and southern EA—for the period 1979–2015 by using the standardized precipitation evapotranspiration index (SPEI) and a hierarchical clustering analysis. According to our analyses, spring drought-prone condition in the northern EA region mainly depends on local surface heating and precipitation deficit due to adiabatic compression by a high-pressure anomaly over the region during the preceding winter to spring. The high-pressure anomaly was driven by an upper-level wave train propagating from the Europe related to a positive phase of the Arctic Oscillation. For drought-prone conditions in the mid and the southern EA regions, the local precipitation deficit caused by the negative moisture advection/convergence therein acts as a primary factor. During the preceding winter, the negative moisture advection/convergence anomalies both in mid and southern EA regions were induced by anomalous low-level cyclonic circulations over the western North Pacific related to the La Niña. In spring, however, the moisture condition in the southern EA region was affected by persistent La Niña while that in the mid-EA region was by the negative phase of North Pacific Oscillation. This gap makes the main location of the negative moisture advection/convergence anomalies just slightly different, but considerably alter the region exposed to the drought-prone condition. Full title: Interannual variations of spring drought-prone conditions over three subregions of East Asia and associated large-scale circulations
- 작성자Park et al.
- 작성일2024.08.22
- 조회수62
- 2020
Improved mapping and change detection of the start of the crop growing season in the US Corn Belt from long-term AVHRR..

Abstract: Long-term monitoring of crop phenology is a critical process to understand changes in cropland vegetation dynamics related to climate and human management. During the last four decades, seasonal changes in vegetation have been measured by satellite instruments, the Advanced Very High Resolution Radiometers (AVHRRs). However, an acceptable detection of crop phenology has been prevented due to its coarse spatial resolution (~8 km) pixels in which croplands are frequently mixed with non-cropland. This study introduces a novel method for detecting the start of the growing season in cropland (SOSC) from the AVHRR Normalized Difference Vegetation Index (NDVI) to examine the long-term changes in SOSC at the 8-km pixel level across the core cropping regions of the Midwestern United States (the so-called ‘the Corn Belt’) for 1982–2015. The AVHRR-based SOSC was compared with the SOSC retrieved from the pixels covering mostly croplands of the 250-m Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI. These two satellite-based SOSC shows reasonable correspondence in spatial patterns so that the annual values of the root mean square difference ranges from 3.6 to 7.4 days during the overlapping period of 2008–2015. Also, an acceptable correspondence was found between the interannual variations in the AVHRR SOSCs and in the state-level survey of crop stages. For sowing stages, correlation coefficients ranged from 0.43 to 0.68; for flowering stages those ranged from 0.51 to 0.83. By analyzing long-term SOSC changes with climate factors, we found a strong tendency that warmer pre-season condition is accompanied with earlier SOSC. In addition, larger pre-season precipitation tends to postpone SOSC as strongly as the pre-season temperature affects SOSC in a considerable portion of the core cropland. This study suggests that the postponing of sowing due to larger precipitation, which has rarely been highlighted in previous studies, requires more attentions in order for better understanding of vegetation dynamics in agriculture-climate studies. Full title: Improved mapping and change detection of the start of the crop growing season in the US Corn Belt from long-term AVHRR NDVI
- 작성자Gim et al.
- 작성일2024.08.22
- 조회수74
- 2020
Impact of Chinese air pollutants on a record-breaking PMs episode in South Korea for 11-15 January 2019

Abstract: A record-breaking episode of highly concentrated particulate matter (PM) with diameters ≤ 2.5 μm (PM2.5) and ≤10 μm (PM10) occurred in the Republic of Korea during the period January 11–15, 2019: the hourly PM2.5 (PM10) in Seoul was 188 μg m−3 (262 μg m-3) on January 14. At the Baengnyeong and Socheongcho stations, located in the Yellow Sea between China and Korea, the hourly PM2.5 concentration reached up to 155 μg m-3 and 119.8 μg m-3, respectively, 16−19-h prior to this episode. This and the fact that the maximum PM10 concentration at Baengnyeong was 199 μg m-3 indicated a westerly transport of air pollutants. Satellite observations and 72-h back trajectory analysis clearly indicate that air pollutants from China flowed into Korea via the westerlies. According to contribution analysis using particulate matter source apportionment technology in the Comprehensive Air-quality Model with extension, air pollutants originating from northeastern China including Hebei and Shandong provinces were largely linked to the present record-breaking high concentration event in Seoul. This study will elucidate the mechanism of transboundary transport of air pollutants and help East Asian countries cooperate on air quality management.
- 작성자Oh et al.
- 작성일2024.08.22
- 조회수53
- 2020
Enhanced regional terrestrial carbon uptake over Korea revealed by atmospheric CO2 measurements from 1999 to 2017

Abstract: Understanding changes in terrestrial carbon balance is important to improve our knowledge of the regional carbon cycle and climate change. However, evaluating regional changes in the terrestrial carbon balance is challenging due to the lack of surface flux measurements. This study reveals that the terrestrial carbon uptake over the Republic of Korea has been enhanced from 1999 to 2017 by analyzing long-term atmospheric CO2 concentration measurements at the Anmyeondo Station (36.53°N, 126.32°E) located in the western coast. The influence of terrestrial carbon flux on atmospheric CO2 concentrations (ΔCO2) is estimated from the difference of CO2 concentrations that were influenced by the land sector (through easterly winds) and the Yellow Sea sector (through westerly winds). We find a significant trend in ΔCO2 of −4.75 ppm per decade (p < .05) during the vegetation growing season (May through October), suggesting that the regional terrestrial carbon uptake has increased relative to the surrounding ocean areas. Combined analysis with satellite measured normalized difference vegetation index and gross primary production shows that the enhanced carbon uptake is associated with significant nationwide increases in vegetation and its production. Process-based terrestrial model and inverse model simulations estimate that regional terrestrial carbon uptake increases by up to 18.9 and 8.0 Tg C for the study period, accounting for 13.4% and 5.7% of the average annual domestic carbon emissions, respectively. Atmospheric chemical transport model simulations indicate that the enhanced terrestrial carbon sink is the primary reason for the observed ΔCO2 trend rather than anthropogenic emissions and atmospheric circulation changes. Our results highlight the fact that atmospheric CO2 measurements could open up the possibility of detecting regional changes in the terrestrial carbon cycle even where anthropogenic emissions are not negligible.
- 작성자Yun et al.
- 작성일2024.08.22
- 조회수62
- 2020
Dominance of large-scale atmospheric circulations in long-term variations of winter PM10 concentrations over East Asia

Abstract: Concentrations of wintertime particulate matters of diameters below 10 μm (PM10) in South Korea and China have decreased since the 2000s largely owing to the emissions reduction policies of the two countries; however, this decreasing tendency has been notably weakened, or even been reversed, in recent years. This study examines the influence of large-scale atmospheric circulations on this PM10 change over East Asia for the winters (December–February) of the 2004/05–2015/16 period using an empirical orthogonal function (EOF) analysis. The first EOF mode, which accounts for 32.7% of the total variance, indicates decreases in PM10 concentrations until 2012 and thereafter increases in them particularly at most stations in eastern and northeastern China. Regression patterns of meteorological variables with respect to the first EOF time series indicate that the wintertime PM10 variations over East Asia are greatly influenced by the Ural blocking; the weakening of the Ural blocking after 2014 led to the weakening of cold air flows from the north and provided atmospheric conditions favorable for bad air quality events over East Asia. The second EOF mode, which accounts for 20.1% of the total variance, shows a similar spatial distribution as the linear trend of PM10 concentrations during the analysis period and would be related to the long-term changes in emissions. Our findings emphasize that the long-term variations in air quality over East Asia are affected primarily by the variations in large-scale atmospheric circulations with secondary contributions from the changes in emissions.
- 작성자Lee et al.
- 작성일2024.08.22
- 조회수67
- 2020
A dipole mode of spring precipitation between southern China and Southeast Asia associated with the eastern and cent...

Abtract: Because spring precipitation in East Asia is critical for recharging water resources after dry winters, its spatiotemporal variations and related mechanisms need in-depth research. This study analyzed a leading spatiotemporal variability of precipitation over East Asia for boreal spring (March-May) during 1979 to 2017. We found that a dipole mode dominates the anomalous spring precipitation between southern China and Southeast Asia with significant interannual and decadal variations. The interannual dipole mode is attributable to the eastern Pacific (EP)-type El Niño-Southern Oscillation (ENSO) while the decadal dipole mode is related to the decadal variation of the central Pacific (CP)-type ENSO. In the El Niño phases of both time scales, the anticyclonic anomaly over the South China Sea and Philippines causes moisture convergence (divergence) over southern China (Southeast Asia), resulting in positive (negative) precipitation anomalies therein; the opposite occurs in the La Niña phases. The ensemble experiments using the Community Atmosphere Model version 5.1 confirmed that the tropical sea surface temperature (SST) in the EP- and CP-type ENSO can be the major drivers of the interannual and decadal dipole modes, respectively. About half of 15 climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) showed that the El Niño phase of dipole mode will become dominant in the future. The individual models' future projections however considerably vary, implying that there is still large uncertainty. Full title: A dipole mode of spring precipitation between southern China and Southeast Asia associated with the eastern and central Pacific types of ENSO
- 작성자Park et al.
- 작성일2024.08.22
- 조회수228
- 2020
Tropical cyclones and climate change assessment: Part II. Projected response to anthropogenic warming

Abstract: Model projections of tropical cyclone (TC) activity response to anthropogenic warming in climate models are assessed. Observations, theory, and models, with increasing robustness, indicate rising global TC risk for some metrics that are projected to impact multiple regions. A 2°C anthropogenic global warming is projected to impact TC activity as follows. 1) The most confident TC-related projection is that sea level rise accompanying the warming will lead to higher storm inundation levels, assuming all other factors are unchanged. 2) For TC precipitation rates, there is at least medium-to-high confidence in an increase globally, with a median projected increase of 14%, or close to the rate of tropical water vapor increase with warming, at constant relative humidity. 3) For TC intensity, 10 of 11 authors had at least medium-to-high confidence that the global average will increase. The median projected increase in lifetime maximum surface wind speeds is about 5% (range: 1%–10%) in available higher-resolution studies. 4) For the global proportion (as opposed to frequency) of TCs that reach very intense (category 4–5) levels, there is at least medium-to-high confidence in an increase, with a median projected change of +13%. Author opinion was more mixed and confidence levels lower for the following projections: 5) a further poleward expansion of the latitude of maximum TC intensity in the western North Pacific; 6) a decrease of global TC frequency, as projected in most studies; 7) an increase in global very intense TC frequency (category 4–5), seen most prominently in higher-resolution models; and 8) a slowdown in TC translation speed.
- 작성자Knutson et al.
- 작성일2024.08.22
- 조회수60
- 2019
Tropical cyclones and climate change assessment: Part I. Detection and attribution

Abstract: An assessment was made of whether detectable changes in tropical cyclone (TC) activity are identifiable in observations and whether any changes can be attributed to anthropogenic climate change. Overall, historical data suggest detectable TC activity changes in some regions associated with TC track changes, while data quality and quantity issues create greater challenges for analyses based on TC intensity and frequency. A number of specific published conclusions (case studies) about possible detectable anthropogenic influence on TCs were assessed using the conventional approach of preferentially avoiding type I errors (i.e., overstating anthropogenic influence or detection). We conclude there is at least low to medium confidence that the observed poleward migration of the latitude of maximum intensity in the western North Pacific is detectable, or highly unusual compared to expected natural variability. Opinion on the author team was divided on whether any observed TC changes demonstrate discernible anthropogenic influence, or whether any other observed changes represent detectable changes. The issue was then reframed by assessing evidence for detectable anthropogenic influence while seeking to reduce the chance of type II errors (i.e., missing or understating anthropogenic influence or detection). For this purpose, we used a much weaker “balance of evidence” criterion for assessment. This leads to a number of more speculative TC detection and/or attribution statements, which we recognize have substantial potential for being false alarms (i.e., overstating anthropogenic influence or detection) but which may be useful for risk assessment. Several examples of these alternative statements, derived using this approach, are presented in the report.
- 작성자Knutson et al.
- 작성일2024.08.22
- 조회수79
- 2019
Tropical cyclone rainfall in the Mekong River basin for 1983–2016

Abstract: As home to about 70 million people, the Mekong River Basin (MRB), located in Mainland Southeast Asia, is often influenced by tropical cyclones (TCs) landfalling. The TCs not only cause flood and storm hazards, but also play important roles in providing freshwater resource and welcomed sediment transports. Our study focuses on the climatology of TCs and associated rainfall (TCR) in the MRB for 1983–2016. Results show that: (i) the mean landfall occurrence of TCs is 6.2 yr-1, leading to 36.7 mm yr-1 of annual mean TCR (2.5% of the annual total precipitation), which mainly occur in monsoon-TC season (i.e., June–November); (ii) TCs highly concentrate on the lower eastern MRB, generating the largest TCR contribution of 12.4% to the annual total precipitation; (iii) the annual mean contribution of TCs induced extreme precipitation - R20mm and R50mm (days of heavy precipitation rate ≥20 mm day-1 and ≥50 mm day-1, respectively) - to that from annual total precipitation is large in the lower eastern MRB; (iv) over 60% of the basin area is influenced by TCR on average; and (v) a significant weakening trend of the TC frequency has been observed. The present findings lay a foundation for further in-depth research of the potential influence of the dynamic TCs and the associated rainfall in the MRB.
- 작성자Chen et al.
- 작성일2024.08.22
- 조회수69
- 2019
TC as a possible remote controller of air quality over the Republic of Korea through poleward propagating Rossby waves

Abstract: Air quality depends as much on large-scale tropospheric circulation as on the amount of pollutant emissions. Many studies have found a relationship between air quality and midlatitude synoptic weather systems. A stable low-level troposphere and airflow from polluted areas are conditions that favor air pollution in a region. However, few studies have focused on the possible remote effect of tropical cyclone (TC) activity in the tropics on air quality in the midlatitude East Asian countries. Here, we found that TCs in the South China Sea (SCS) can increase the concentration of particulate matter with aerodynamic diameters less than 10 μm (PM10) over South Korea through poleward-propagating Rossby waves. According to our analyses, intense divergence due to a TC causes a barotropic Rossby wave train from the SCS to the North Pacific Ocean. Anomalous highs over the Korean Peninsula (part of the Rossby wave train) result in stable air conditions and cause polluted air inflow to increase the PM10 concentration up to 65 μg m-3. Our finding suggests that TC activity in the tropics should be considered for more accurate forecasts of air quality in South Korea. Full title: Tropical Cyclone as a possible remote controller of air quality over the Republic of Korea through poleward propagating Rossby waves
- 작성자Park et al.
- 작성일2024.08.22
- 조회수59
- 2019
The tropical transition in the western North Pacific: The case of tropical cyclone Peipah (2007)

Abstract: This study examines the transition of an extratropical disturbance to a tropical cyclone (TC), Peipah (2007), in the western North Pacific (WNP), using reanalysis and geostationary satellite data. Instead of regular diurnal fluctuations of deep convection, the pre-TC disturbance accompanies deep convection only for short durations every other day. When the pre-TC vorticity is traced back to 7 days prior to its formation, the traced-back vorticity indicates a strong potential vorticity (PV) trough in the subtropical upper troposphere that originated from the midlatitude lower stratosphere. The quasi-geostrophic forcing and reduced static stability at the leading edge of the PV trough result in the formation of an extratropical disturbance. The vertical structure of the extratropical disturbance shows maximum vorticity in the upper troposphere and cold temperature anomaly within it throughout the entire troposphere. As the extratropical disturbance moved into the tropical WNP, deep convection associated with quasi-geostrophic dynamics over the warm ocean initiated tropical transition of the extratropical disturbance to a TC through diabatic redistribution of PV in the tropospheric column as well as transition of the cold anomaly into a warm anomaly within the vortex. With additional contribution of barotropic energy conversion in the lower troposphere, the warm-core low system finally developed into a TC-strength vortex. These results indicate that PV troughs of the stratospheric origin over the subtropical Pacific Ocean can contribute to TC formations in the WNP.
- 작성자Chang et al.
- 작성일2024.08.22
- 조회수63
- 2019
Possible link between Arctic Sea ice and January PM10 concentrations in South Korea

Abstract: In this study, we investigated the possible teleconnection between PM10 concentrations in South Korea and Arctic Sea ice concentrations at inter-annual time scales using observed PM10 data from South Korea, NCEP R2 data, and NOAA Sea Ice Concentration (SIC) data from 2001 to 2018. From the empirical orthogonal function (EOF) analysis, we found that the first mode (TC1) was a large-scale mode for PM10 in South Korea and explained about 27.4% of the total variability. Interestingly, the TC1 is more dominantly influenced by the horizontal ventilation effect than the vertical atmospheric stability effect. The pollution potential index (PPI), which is defined by the weighted average of the two ventilation effects, is highly correlated with the TC1 of PM10 at a correlation coefficient of 0.75, indicating that the PPI is a good measure for PM10 in South Korea at inter-annual time scales. Regression maps show that the decrease of SIC over the Barents Sea is significantly correlated with weakening of high pressure over the Ural mountain range region, the anomalous high pressure at 500 hPa over the Korean peninsula, and the weakening of the Siberian High and Aleutian low. Moreover, these patterns are similar to the correlation pattern with the PPI, suggesting that the variability of SIC over the Barents Sea may play an important role in modulating the variability of PM10 in South Korea through teleconnection from the Barents Sea to the Korean peninsula via Eurasia.
- 작성자Kim et al.
- 작성일2024.08.22
- 조회수61
- 2019
Near-future tropical cyclone predictions in the western North Pacific: Fewer tropical storms but more typhoons

Abstract: This study presents forecasts of near-future tropical cyclone (TC) activities over the western North Pacific (WNP) using a TC track-pattern-based prediction model in conjunction with long-term free-run simulations from the National Centers for Environmental Prediction Climate Forecast System. The prediction shows that the East Asian coastal area will be affected by fewer TC landfalls. However, the number of stronger TC landfalls may increase in the near future (2016–2030) com pared to the present-day period (2002–2015). The potential candidates for modulating the near-future TC activity are three large-scale climate variability: El Niño–Southern Oscillation (ENSO), the North Pacific sea surface temperature (NPSST) variation, and basin-wide warming of the Pacific. More frequent El Niño episodes in the near future may contribute to the activation of TC formations in the far-eastern tropical ocean, which generates a favorable influence on TC intensification due to longer distances and development periods over the ocean. NPSST variations have contrasting effects, i.e., they have unfavorable effects on TC genesis due to weak vorticity, while creating favorable conditions for TC intensification by pro viding more humid environments in the subtropics. The impact of overall Pacific warming on the changes in TC activities is low compared to that of the other two factors. Our results physically demonstrate the contributions of three WNP sea surface temperature variability on near-future TC activity, emphasizing the critical roles of ENSO and NPSST rather than the near-term warming effect.
- 작성자Choi et al.
- 작성일2024.08.22
- 조회수67
- 2019