Chang-Hoi Ho

Chang-Hoi Ho
Seoul National University | SNU · Department of Earth and Environmental Sciences

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254
Publications
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Publications

Publications (254)
Article
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 l...
Article
This study summarized the procedure for the seasonal predictions of tropical cyclones (TCs) over the western North Pacific (WNP), which is currently operating at the Korea Meteorological Administration (KMA), Republic of Korea. The methodology was briefly described, and its prediction accuracy was verified. Seasonal predictions were produced by syn...
Article
Full-text available
Plain Language Summary The location where tropical cyclone (TC) attains their lifetime maximum intensity is an important factor to determine the magnitude of its societal impact. Considering the land‐sea distribution in the Atlantic, poleward migration of the location means that the TC can grow longer until it closer to the land. Besides, the locat...
Article
The recurrent neural network (RNN), an artificial intelligence algorithm, applied to the predictions based on the Community Multiscale Air Quality operational model has significantly improved the forecast accuracy of the concentrations of particulate matter with a diameter of ≤2.5 μm (PM2.5) in the Seoul metropolitan area of the Republic of Korea....
Article
Full-text available
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...
Article
Full-text available
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, C...
Article
Full-text available
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) type...
Article
This study examined meteorological effects on airborne concentrations of particulate matter (PM) of <2.5 μm (PM2.5) and 2.5–10 μm (PM2.5–10) diameter in 16 regions of Korea, including seven metropolitan cities and nine provinces. Regional distributions of mean PM concentrations indicate that PM2.5 concentrations were higher in provinces than in met...
Preprint
Full-text available
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...
Article
Full-text available
A novel coronavirus disease (COVID-19) continues to challenge the whole world. The disease has claimed many fatalities as it has transcended from one country to another since it was first discovered in China in late 2019. To prevent further morbidity and mortality associated with COVID-19, most of the countries initiated a countrywide lockdown. Whi...
Article
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Despite tremendous advancements in dynamical models for weather forecasting, statistical models continue to offer various possibilities for tropical cyclone (TC) track forecasting. Herein, a track-pattern-based approach was developed to predict a TC track for a lead time of 6–8 days over the western North Pacific (WNP), utilizing historical tracks...
Article
Full-text available
The Government of the Republic of Korea has enforced strict regulations to improve air quality since the early 2000s. The regulations are mainly focused on reducing vehicle emissions in the Seoul metropolitan region by conforming to the European emissions standards, replacing diesel buses with compressed natural gas buses, incentives for installing...
Article
Full-text available
Variations in concentrations of PM2.5, particulate matters of diameters below 2.5 μm, vary following both meteorological conditions and emissions controls. Meteorological conditions particularly affect short‐term high PM2.5 episodes through accumulations, transports, and secondary formations. This study quantifies the meteorological impacts on high...
Preprint
Full-text available
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, C...
Article
Tropical cyclones (TCs) are one of the most devastating storm systems with high socioeconomic impacts around the world. The drivers of long-term changes in TC frequency and intensity, including the recent global climatic changes, are, however, poorly understood due to short instrumental measurements and a lack of accurate proxy records. Here we pre...
Article
The National Institute of Environmental Research, the Ministry of Environment, has been forecasting the concentrations of particulate matter (PM) with a diameter ≤ 2.5 μm (PM2.5) over Seoul, Republic of Korea, in terms of four PM2.5 concentration categories (low, moderate, high, and very high) since August 31, 2013. The current model, the Community...
Article
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 y...
Article
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An abrupt decrease in annual tropical cyclone genesis frequency (TCGF), which is statistically significant only from October to December (OND), has been noticed over the western North Pacific Ocean. However, the seasonal inhomogeneity of interdecadal changes in TCGF between OND and the other seasons (from January to September) and the associated me...
Article
Understanding the mechanisms related to the variations in the rainfall structure of tropical cyclones (TCs) is crucial in improving forecasting systems of TC rainfall and its impact. Using satellite precipitation and reanalysis data, we examined the influence of along-track large-scale environmental conditions on inner-core rainfall strength (RS) a...
Article
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Summertime heat stress future projections from multi-model mean of 18 CMIP5 models show unprecedented increasing levels in the RCP 4.5 and RCP 8.5 emission scenarios over India. The estimated heat stress is found to have more impact on the coastal areas of india having exposure to more frequent days of extreme caution to danger category along with...
Article
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...
Article
Full-text available
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 stand...
Article
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Global warming and its associated changes in the timing of seasonal progression may produce substantial ripple effects on the regional climate and ecosystem. This study analyzes the surface air temperature recorded during the period 1919–2017 at seven stations in the Republic of Korea to investigate the long-term changes at the beginning and ending...
Article
Because spring precipitation in East Asia is critical for recharging water resources after dry winter, its spatiotemporal variations and related mechanisms needs in-depth research. This study analyzed a leading spatiotemporal variability of precipitation over East Asia for the boreal springs (March–May) in 1979−2017. We found that a dipole mode dom...
Article
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 lar...
Article
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 Kore...
Article
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...
Article
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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 initialize...
Article
Full-text available
In 2018, heatwaves (HWs), which are defined as period of abnormally hot weather with the daily maximum temperature (T_Max) exceeding its 95th percentile threshold for at least three consecutive days, were prevalent during June to August, and temperature records were broken in many countries over East Asia (EA) including China (CH), Japan (JP), and...
Article
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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 Concentration Pathway (RCP) 8.5 and the new two limiting local greenhouse gas emission scenarios in East Asia: Nation...
Article
Full-text available
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...
Article
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 hav...
Article
Full-text available
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 fo...
Article
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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 wi...
Article
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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 cr...
Article
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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....
Poster
Full-text available
As home to 70 million people, the Mekong River Basin (MRB), located in Mainland Southeast Asia, is often affected by tropical cyclones (TCs) landfall. TCs not only cause flood and storm hazards, but also play important roles in providing freshwater resource and welcomed sediment transports. Our study aims at creating a climatology of TCs and TC ind...
Article
Full-text available
The wind- and rainfall areas of tropical cyclones (TCs) making landfall over South Korea were examined for the period 1998–2013 by using the Modern Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) and Tropical Rainfall Measuring Mission (TRMM) 3B42 data. Here, the wind- and rainfall areas were defined as the regions whe...
Article
Full-text available
Several previous studies on tropical cyclone (TC) risk assessment have attempted to quantify the relationship between TC damage and its elements (i.e. exposure, vulnerability, and hazard). For hazard parameters, TC intensity (e.g. central minimum pressure, maximum wind speed) and size information (e.g. 30 knot radius of the TC) have been widely uti...
Article
There is a consensus that the spring phenology of deciduous forests is advancing in response to global warming. Since the late 1990s, however, this tendency of spring phenology advancement has been weakened in over 60% of boreal forests, particularly in Siberia (−0.58 day yr⁻¹ for 1982–1997 vs. −0.17 day yr⁻¹ for 1982–2013) and northwestern North A...
Article
Urbanization exerts anthropogenic forcing that affects regional climate and ecosystems. With increasing levels of urbanization associated with urban population growth in the near future, understanding of the impact of urbanization on terrestrial ecosystems is important for predicting future environmental changes. This study evaluates the impact of...
Article
Cold-season air quality in Seoul, South Korea, has been improved noticeably between 2001 and 2015 with a near-50% decrease in the mean concentration of particulate matter with aerodynamic diameters ≤10 μm (PM10). Like the change in mean concentration, the occurrence frequency and intensity of the extreme-high-PM10 episodes exceeding 100 μg m⁻³ has...
Article
Full-text available
The spatiotemporal distribution of summer rainfall is diverse in origin, namely tropical cyclones (TCs) and quasi-stationary monsoon frontal systems. Here, the contribution of TCs to summer rainfall is singled out for the years of strong vs. weak Changma/Baiu, which is represented by the leading mode of the variability in total rainfall over East A...
Article
Full-text available
In Seoul, South Korea, particulate matters (PMs) significantly decreased for the period 2005–2015 in concert with the implementation of air pollution reduction policies. This study reveals that PM with a diameter smaller than 2.5 μm (PM2.5) has a slower decreasing tendency than PM in the 2.5–10-μm range (PM2.5-10) during summer and that this discre...
Article
Understanding the variations in spring vegetation phenology associated with preseason climate conditions can significantly improve our knowledge on ecosystem dynamics and biosphere-atmosphere interactions. Recent studies have shown that wet winters can delay the start date of the vegetation growing season (SOS) in the high latitudes. However, assoc...
Article
Full-text available
The occurrence of wintertime cold surges (CSs) over East Asia is largely controlled by the surface air temperature (SAT) distribution at high latitudes and thermal advection in the lower troposphere. The thermodynamic background state over northeastern Asia is associated with the strength of the East Asian winter monsoon and the variation of Arctic...
Article
In this study, the variation of tropical cyclone (TC) rainfall area over the subtropical oceans is investigated using the Tropical Rainfall Measuring Mission precipitation data collected from 1998 to 2014, with a focus on its relationship with environmental conditions. In the subtropics, higher moving speed and larger vertical wind shear significan...
Article
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Regional warming, owing to urbanization, leads to earlier spring phenological events and may expose plants to hard freeze damage. This study examined the influence of urbanization on the risk of frost damage to spring flowers in South Korea from 1973 to 2015. For the analysis period, we categorized 25 cities into two groups: those showing rapid pop...
Article
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Aridity—the ratio of atmospheric water supply (precipitation; P) to demand (potential evapotranspiration; PET)—is projected to decrease (that is, areas will become drier) as a consequence of anthropogenic climate change, exacerbating land degradation and desertification1,2,3,4,5,6. However, the timing of significant aridification relative to natura...
Article
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In tropical cyclone (TC) risk assessment, many of previous studies have attempted to construct the statistical relationship of TC damage and three risk elements–exposure, vulnerability, and hazard. For hazard parameters, central minimum pressure, maximum wind speed, and size have been widely utilized while track was not mainly considered as one of...
Article
Full-text available
Long‐term variations of seasonal‐mean surface air temperature in South Korea. The surface warming is dominated by abrupt jumps in temperature for winter and summer, whereas it is rather gradual for spring and autumn. A number of studies on the surface warming in the Korean Peninsula reported that there has been a notable increasing trend of surface...
Article
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Understanding changes in background dryness over land is key information for adapting to climate change because of its critical socioeconomic consequences. However, causes of continental dryness changes remain uncertain because various climate parameters control dryness. Here, we verify dominant climate variables determining dryness trends over con...
Article
Full-text available
Prediction of tropical cyclone (TC) activity is essential to better prepare for and mitigate TC-induced disasters. Although many studies have attempted to predict TC activity on various time scales, very few have focused on near-future predictions. Here a decrease in seasonal TC activity over the North Atlantic (NA) for 2016-30 is shown using a tra...
Article
In the land surface models predicting vegetation growth and decay, representation of the seasonality of land surface energy and mass fluxes largely depends on how to describe the vegetation dynamics. In this study, we developed a new parameterization scheme to characterize allocation of the assimilated carbon to plant parts, including leaves and fi...