East Sea Research Articles

A new species of the genus Caprella Lamarck, 1801 (Crustacea, Amphipoda, Caprellidae) from Korea

A new species of the genus Caprella, belonging to the family Caprellidae, has been collected from the East Sea of Korea. The new species, Caprella megabranchia sp. nov., is morphologically similar to C. brevirostris Mayer, 1903, in terms of the shape of the propodus of gnathopod 2 and pereopods 5–7, propodi lacking grasping robust seta. However, the new species can be easily distinguished from C. brevirostris by its entirely circular gills and the anterior convexity of peduncular article 3 in antenna 1. The new species is illustrated and compared to related species C. brevirostris and a key to the Caprella species in Korea is also provided.

Revisiting the Tianwen Yellow Pumice (TYP) Eruption of Changbaishan Volcano: Tephra Correlation, Eruption Timing and Its Climatostratigraphical Context

AbstractChangbaishan volcano (China/North Korea) is one of the most active and hazardous volcanic centers in Northeast Asia. Despite decades of intensive research, the eruption history of this stratovolcano remains poorly constrained. One of the major puzzles is the timing of the eruption that produced the Tianwen Yellow Pumice (TYP) deposit at the caldera rim. Here we identify a new cryptotephra layer in sediment core 13PT‐P4 from the East Sea. Grain‐specific major, minor, and trace element analyses of glass shards allow a clear correlation of this distal tephra to the proximal TYP deposit of Changbaishan. Age‐depth modeling using radiocarbon (14C) dates of sediment bulk organic fractions and other tephrochronological markers from the sediment sequence constraints the age of the cryptotephra and thus the TYP eruption to 29,948–29,625 cal yr BP (95.4% confidence interval). Our findings lead to a revision of the history of Changbaishan explosive activity, and show that the volcano has been particularly active during ca. 51–24 ka BP in the last 100 ka. Using high resolution palaeo‐proxy records, we find the TYP tephra almost coeval with regional to hemispheric‐scale climatic changes known as Heinrich Event 3 (H3). With its precise age determination and wide geographic dispersion, the tephra offers a key isochron for dating records of past climatic changes and addressing the phasing relationships in environmental response to H3 across East Asia.

Detection of Microplastics and Heavy Metals in Famous Edible Molluscs in Can Gio Biosphere Reserve of Vietnam

Can Gio, designated in 2000, is the first Biosphere Reserve of Vietnam. In recent years, local agriculture, tourism, households, nearby industrial zones, and maritime transport have released substances into rivers flowing through Can Gio Mangrove to the East Sea and transported into creatures. This study aims to investigate microplastics and heavy metals in the famous seafood of Can Gio. A Raman microscope was used to identify microplastics from the tissue of oysters, grease snails, and clams after enzymatic treatment with trypsin. Heavy metals were quantified with ICP-MS after acidic treatment. As a result, microplastics were found in almost all samples, even up to 10 in a random individual of bivalve. Fibers dominated, especially from 30 to 150 µm long. The metal with the highest content was zinc, followed by copper, especially in oysters. Non-essential metals were also present in the soft tissue in the order As > Pb > Cd. The accumulation of metals in Can Gio’s molluscs was generally lower than in other regions and still in the allowed range for consumption of Vietnamese Standard. Although there have not been any Vietnamese regulations on the permissible level of microplastics for consumption, regular seafood intake will increase the risk of chronic poisoning and unknown disorders caused by the accumulation of microplastics and heavy metals.

The Long-Term Dynamics of Walleye Pollock Stocks in Relation to Oceanographic Changes in the East Sea

The decline in walleye pollock (Gadus chalcogrammus) stocks in Korean waters is a major concern for fishery conservation and management. However, the causes and mechanisms of this collapse remain unclear. This study investigated the complex dynamics influencing the abundance of walleye pollocks in the East Sea of Korea over several decades, by analyzing data from long-term changes in biological factors including composition of length and sex, catch, and oceanographic condition. Prior to the mid-1980s, the catch ratio of juveniles was higher than that of adults, with a higher proportion of females in both juvenile and adult catches compared to males. Especially, high fishing pressure on female individuals can be an important factor contributing to declining reproduction. Consequently, after the mid-1980s, there was a sudden decline in juvenile pollock catches. In the late 1980s, there was a rapid increase in sea surface temperature (SST) in the spawning grounds, resulting in a decrease in both the duration of suitable temperature for spawning and the regional proportion for suitable spawning conditions. Consequently, the decline in pollock stocks after the late 1980s due to overfishing of pollock in the mid-1980s was further exacerbated by the effects of SST warming after the late 1980s. These findings highlight the impact of overfishing and environmental factors on pollock stocks and indicate the need for appropriate fishery management practices to ensure the sustainable use of fishery resources.

New Species of Eupelte (Crustacea, Copepoda, Harpacticoida) from the East Sea, with Notes on the Zoogeography of the Genus

A new species of the genus Eupelte Claus, 1860, was obtained from the algal bed bottom in Dokdo Island, East Sea of Korea, using a light trap. Specimens of both sexes of the Korean new species are described in detail and compared with its congeners. The present species, Eupelte dokdoensis sp. nov., is closely similar to E. aurulenta Wells and Rao, 1987, found in algal sands from the Andaman and Nicobar Islands, and E. setacauda Monk, 1941, collected from seaweeds in the Californian coast of the USA. These species share the body length (0.5–07 mm), the nine-segmented A1, the setation of the first and second endopodal segments of P1 (one and four setae), P4 exp-3 with three inner setae, and enp-3 of P2–P4 with five setae in both sexes. The new species can be readily discernable from the previous two species by the short rostrum with a serrate distal margin, the shape of the maxillipedal basis, the setation and surface ornamentation of P1 enp-2 (covered with long setules), the exp-3 of P3 and P4 with thicker middle inner seta, and the setation of female and male P5 exopod and baseoendopod (six and six, four and two setae, respectively). In addition, the zoogeography of the valid species of the genus Eupelte is briefly discussed, and a diagnostic key to the females of the species is provided. Eupelte dokdoensis sp. nov. described herein is the first report of the genus from Korean waters and is the fourteenth member of the genus.

Near-Future Projection of Sea Surface Winds in Northwest Pacific Ocean Based on a CMIP6 Multi-Model Ensemble

Information about wind variations and future wind conditions is essential for a monsoon domain such as the Northwest Pacific (NWP) region. This study utilizes 10 Generalized Circulation Models (GCM) from CMIP6 to evaluate near-future wind changes in the NWP under various climate warming scenarios. Evaluation against the ERA5 reanalysis dataset for the historical period 1985–2014 reveals a relatively small error with an average of no more than 1 m/s, particularly in the East Asian Marginal Seas (EAMS). Future projections (2026–2050) indicate intensified winds, with a 5–8% increase in the summer season in the EAMS, such as the Yellow Sea, East Sea, and East China Sea, while slight decreases are observed in the winter period. Climate mode influences show that winter El Niño tends to decrease wind speeds in the southern study domain, while intensifying winds are observed in the northern part, particularly under SSP5-8.5. Conversely, summer El Niño induces higher positive anomalous wind speeds in the EAMS, observed in SSP2-4.5. These conditions are likely linked to El Niño-induced SST anomalies. For the application of CMIP6 surface winds, the findings are essential for further investigations focusing on the oceanic consequences of anticipated wind changes such as the ocean wave climate, which can be studied through model simulations.

Effects of jetstream on seasonal variations of tropical cyclone tracks in the East Sea

Tropical cyclones (TCs) frequently occurs and result in substantial socio-economic consequences for the countries around the East Sea. In this study, the Joint Typhoon Warning Center (JTWC) best tracks and the NCEP/NCAR reanalysis data are employed to investigate the effect of jetstream on the seasonal variations of the TC tracks. The results reveal four primary directions of the tracks: northeastward, northwestward, westward and southwestward. A low-level anomalous cyclone moving from the Western North Pacific (WNP) to the Indochina Peninsula (IP) plays a significant role in guiding the movement of the TCs. This anomalous cyclone is strongly modulated by the development of a wavetrain along the subtropical jetstream. In May, the wavetrain induces strong anomalous divergence to the east of China, leading to the northeastward expansion of the low-level anomalous cyclones, thereby directing the TCs to the northeast. From June to August, the jetstream shifts to higher latitudes, reducing its impact on the TC tracks. From September to December, the jetstream moves back to the south; however, its effect on the TC tracks is opposite to that in May. During this time, the wavetrain accelerates an anomalous anticyclone in Southeast China and the Western North Pacific, which in turn pushes the anomalous cyclone to the south and promotes westward and southwestward movement of the TCs in the East Sea.

Intrinsic Low-Frequency Variability in the Upper-Layer Circulation of the East Sea (Sea of Japan)

Abstract The effects of external forcing variation on the intrinsic variability in the upper-layer circulation occurring within the East Sea (Sea of Japan) and its physical mechanism are analyzed using numerical experiments. In this study, the experiments were conducted with climatological annual/monthly mean forcings (constant/seasonal forcings). The intrinsic variability is mainly distributed in the meandering regions around the main current path with the comparatively large variability limited to the southern region. The reason of greater intrinsic variability mainly in the southern part of the East Sea than in the northern part is that more energy is required from external forcings to change the thicker upper layer formed in the northern part due to seasonal forcings (strong wind stress and surface heat flux). Although the experiments show slight differences, westward propagation of the Rossby wave appears in areas where the variability is large. The transport of the eddy momentum flux associated with the Rossby wave modulates the strength of the eastward jet and the north–south shift of its axis. Among the external forcings, the volume transport through the Korea/Tsushima Strait is the most important driver of intrinsic variability, and wind stress plays an important role in expanding and strengthening intrinsic variability. Significance Statement Intrinsic variability is an important factor in understanding the total variability in the upper-layer circulation in the East Sea (Sea of Japan). However, the physical mechanisms of intrinsic variability remain unclear. This study investigates the physical mechanisms of intrinsic variability occurring within the East Sea. The intrinsic variability occurs mainly around the main current path, especially the meandering current. Based on numerical experiments, the mechanism of the intrinsic variability is represented by the fluctuation in the strength of the eastward current or the north–south movement of its axis caused by the Rossby wave.

Toxicity evaluation of a strain isolated from pollack digestive tract using Paramecium caudatum

A strain was isolated from the digestive organs of Walleye pollack residing in the East Sea of the DPR Korea, which not only produces cryophilic protease, organic acid but also has intestinal adhesion property and bacteriostatic activity against pathogens. The strain was classified and identified as Pseudomonas fragi by genetic system classification methods and registered as KCCC 10110 at the Korean Centre for Culture Collection (KCCC) of the State Academy of Sciences, DPR KOREA. In vivo and in vitro toxicity of Pseudomonas fragi KCCC 10110 was evaluated using Paramecium caudatum. In the treatments with P. fragi KCCC 10110, Bacillus subtilis KCCC 11214 and Lactobacillus lactis KCCC 13208, all of these being well known as non-toxic and probiotic for animals and fishes, higher microbial counts and normal movement of P.caudatum were observed while significant lower cell numbers and abnormal movement of P.caudatum were shown in the treatments with pathogenic strains Clostridium tetani 473, Salmonella typhosa 901 and Aeromonas punctata 823. These results suggest that probiotic and pathogenic bacteria have different influence on Paramecium caudatum and that the strain isolated from Walleye pollack digestive tract is non-toxic.

해양환경모니터링 네트워크 자료를 이용한 동해연안 수온, 용존산소 농도의 계절과 연직 분포차이 검정

해양환경모니터링 네트워크 자료를 이용한 동해연안 수온, 용존산소 농도의 계절과 연직 분포차이 검정

Application of wetPf2 Data for Investigating Characteristics of Temperature and Humidity of Air Masses over Paracel and Spratly Islands

This article uses data from the second-generation Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC-2) satellites (wetPf2) to study the temperature and humidity properties of the air masses over Paracel and Spratly Islands in the Vietnam East Sea (South China Sea). The satellite observational data were validated with the radiosonde data from three stations in Vietnam: Hanoi, Danang, and Ho Chi Minh City. Subsequently, the wetPf2 data are used to analyze the characteristics of temperature and relative humidity variations of the air masses over the Paracel and Spratly regions. Results show that the mean error of the satellite observational data for temperature ranges from −0.06°C to −0.02°C, with standard deviations ranging from 0.73°C to 1.04°C. The mean error of relative humidity fluctuates between 11.6% and 12.5%, with standard deviations ranging from 15.1% to 19.1%. The values are reasonable and comparable to those in previous studies. Seasonal variations of temperature and humidity show that the air mass over the Paracel Islands exhibits a larger annual temperature with an annual variation of approximately 5.0°C, significantly higher than the value of 2.2°C in the air mass over the Spratly Islands. The difference may be due to the greater influence of continental and seasonal wind systems in the northern region. Within both air masses, the annual temperature variation in the boundary layer is much larger than that in the free atmosphere. Annual relative humidity variation is higher in summer and autumn than in winter and spring. The significant changes in the relative humidity with height during winter and no significant change of the relative humidity with height during summer may be related to the important role of strong convective activity carrying moist air upward to higher atmospheric levels during the summer time.

The host range and distribution pattern of rhizocephalan parasitic barnacles in Korean coasts and their relationship with geographical factors

IntroductionThis study undertakes a detailed examination of the host range and distribution patterns of Rhizocephala, a group of specialized parasitic barnacles, within Korean marine environments. It aims to expand the understanding of their biodiversity and ecological impact.MethodsEmploying both morphological observation and mitochondrial DNA sequencing, the study identifies the variety of rhizocephalan species infecting decapod hosts in Korean waters, aiming to document their diversity and distribution.ResultsThe investigation identifies 26 rhizocephalan species parasitizing 28 decapod hosts, including the discovery of three new parasite-host relationships not previously reported. It was observed that while a few rhizocephalan species infect multiple hosts, most have a narrow host range. Additionally, the study maps out regional differences in Rhizocephala diversity across three Korean marine ecoregions, noting the highest diversity in the warmer East China Sea ecoregion and lower diversity in the colder Yellow Sea and East Sea ecoregions.DiscussionThe findings underscore the necessity for continued taxonomic research on Rhizocephala and their host species to better understand and manage these parasites, which hold significant ecological and economic importance. The study suggests that geographical variations in host-parasite relationships are influenced by regional climatic conditions, particularly winter water temperatures.

Intrinsic Mode-Based Network Approach to Examining Multiscale Characteristics of Sea Surface Temperature Variability

Variability of sea surface temperature (SST), characterized by various spatiotemporal scales, is a proxy of climate change. A network analysis combined with empirical mode decomposition is newly presented for examining scale-dependent spatial patterns of SST variability. Our approach is applied to SST anomaly variability in the East/Japan Sea (EJS), consisting of satellite-derived daily datasets of 0.25° × 0.25° resolution from 1981 to 2023. Through the spatial distribution of instantaneous energy in intrinsic modes and features of intrinsic-mode networks, scale-dependent spatiotemporal features are found. The season-specific spatial pattern of energy density is observed only for weekly to semiannual modes, while a persistent high-energy distribution in the tongue-shaped region from East Korea Bay (EKB) to the Sub-Polar Front (SPF) is observed only for annual-to-decadal modes. The seasonality is apparent in the time evolution of energy only for weekly-to-annual modes, with a peak in summer and an increasing trend since the 2010s. Hubs of intrinsic-mode networks are observed in the whole southern area (some northern part) of EJS during the summer (winter), only for monthly to semiannual modes. Regional communities are observed only for weekly to seasonal modes, while there is an inter-basin community with annual-to-biennial modes, incorporating two pathways of East Sea Intermediate Water (ESIW).

Subsurface evolution of three types of surface marine heatwaves over the East Sea (Japan Sea)

Extremely high seawater temperatures (beyond the 90th percentile threshold) are a key characteristic of marine heatwaves (MHWs), which adversely affect human and marine ecosystems. It is important to characterize the MHWs in the East Sea (Japan Sea), a semi-enclosed deep basin connected to the outside seas/ocean by shallow and narrow straits, where the most rapid upper ocean warming has been reported in recent decades. Despite several reports on their rising frequency and severity, the characteristics, and underlying dynamics of East Sea MHWs (ESMHWs), particularly their subsurface evolution, remain poorly understood. In this study, we aimed to understand the subsurface evolution patterns of ESMHWs and the underlying mechanisms. Here, summer (June, July, and August) ESMHWs from four ocean reanalysis products were characterized after being verified against those from long-term (2000–2015) time-series observations near the east coast of Korea. We found the HYCOM reanalysis products is the best match with the observation, showing consistent evolution patterns with the ESMHWs in the observation, yielding high correlation coefficients (ranging from 0.7 to 0.9 at the surface), and low root-mean-square errors (3°C). Therefore, the HYCOM reanalysis is further used to characterize the subsurface evolution of surface ESMHWs. A rising frequency of annual mean and summer ESMHWs across the whole East Sea, with a maximum increasing rate of 1–2 events in 40 years and mean cumulative intensity of 5–9°C days decade-1. Three types (Types-A, -B, and -C) of subsurface evolution of ESMHW were commonly found in six sub-regions (where the increasing ESMHWs trends are maximum)—three in the western and three in the eastern parts. The three types are Type-A, which is surface-confined and short-lived with anomalous warm surface temperatures and cold subsurface temperatures; Type-B, characterized by warm anomalies propagating from the surface to the upper several meters with no subsurface cold anomalies; and Type-C, exhibiting anomalous warm temperatures at the upper 200 m. Although increased shortwave radiation, decreased wind speed, and thinned mixed layer commonly contribute to the formation of all three types, the relative role of the heat penetration into the layer below the mixed layer and dissipation mechanisms significantly differ among the types. Common ESMHW evolution features include mixed layer deepening, heat release to the atmosphere, and interactions between the surface mixed layer and deeper layers, while horizontal advection played a significant role only during the Type-C ESMHW events. The long-term trends in frequency, cumulative intensity, and duration of ESMHWs were discussed in terms of those in each type ESMHWs metrics along with long-term surface warming, subsurface cooling, and weakening currents in the six sub-regions. This study provides significant insights into surface and subsurface evolution of MHWs in this and other marginal seas in warming climate conditions.

What next for marine ecosystem management in Vietnam: assessment of coastal economy, climate change, and policy implication

Vietnam is a coastal country with a coastline stretching more than 3,260 km. Marine resources are important for the development of Vietnam. In Vietnamese seas, there are about 20 typical ecosystems spreading over 1 million square kilometers in the East Sea consisting of mangrove forests, coral reefs, lagoons, seagrasses in intertidal areas and estuaries, and living species in 155,000 hectares, 1,300 square kilometers, 500 square kilometers, 16,000 hectares, and 11,000 living species, respectively. At present, the impact of climate change, socio-economic development, and environmental pollution are considered as the main causes of degradation of Vietnam’s marine ecosystems. This paper presents and discusses the pressure of socio-economic activities including industry, tourism, marine transportation and services, aquaculture and fishery on marine ecosystems. In Vietnam, compared to the early 2000s a total of 12% of coral reefs, and 48% of other coral reefs are vulnerable to degradation. So far, about 100 species of marine life in Vietnam are at risk of being threatened due to over-exploitation and fishing. The seagrass-bed ecosystem is currently being degraded with only over 5,580 ha remaining. In some areas, such as Cat Ba, Ha Long, and Quang Nam, seagrass beds have almost no chance to recover naturally due to serious impacts from tourism and aquaculture activities. From the findings, orientations that aim at effective management and protection of marine ecosystems to cope with adverse impacts of anthropogenic activities, climate change, and the pressure of socioeconomic development were proposed.

Horizontal and vertical movement patterns of yellowtail (Seriola quinqueradiata) in the East Sea of Korea

Horizontal and vertical movement patterns of yellowtail (Seriola quinqueradiata) in the East Sea of Korea

금호강 유역 고려분묘 출토 도기 줄무늬병 연구

The pottery striped bottle of the Goryeo Dynasty is a characteristic bottle found in tombs in the Yeongnam area and this has received attention in that it reveals the locality of the Yeongnam region. This paper examined the process of change in the bottle, paying attention to the phenomenon that the striped bottle is intensively distributed in the Geumhogang River basin.
 The first period (middle 11th century to late 12th century) is the period in which hemispheric striped bottle and trumpet-mouth striped bottle coexist. The two types of striped bottles differ in the distribution range. Hemispheric striped bottles are excavated from the Nakdong River to the Geumho River, and trumpet-mouth striped bottles are excavated from the East Sea coast to the Geumho River. In the second period (13th century to 14th century), the trumpet-mouth striped-bottle was used alone, and the striped bottle culture, which developed in two directions through different routes, showed an integrated aspect centered on the Geumho River.
 The Geumho River basin is an important transportation hub, and the limited excavation pattern of the distribution of the striped bottle from the mid-stream of the Nakdong River to the East Sea is thought to be closely related to the distribution system formed around the road system of the time. In addition, this is an area that has long held the identity of the Silla people and the production base of earthenware early on, the earthenware production system. In this study, I tried to reveal the existence of a pottery production system shared in the Geumho River basin from the mid to late Goryeo period.

Evaluation of the Neogene depositional dynamics in the Malay-Tho Chu Basin based on seismic analysis: effects of local and regional tectonism and paleoclimatic variations

Depositional environments in areas located near sea level are vulnerable to even subtle changes in both tectonism, climate and eustatic sea level. Sorting out mechanisms behind depositional changes in inner shelf-margins and epeiric seas is therefore far from straight forward. The epeiric Malay-Tho Chu Basin, located in the shallow Gulf of Thailand offshore Vietnam, contains a thick uppermost Oligocene to Recent post-rift succession. Based on 18000 km of 2D seismic profiles, the uppermost Oligocene-Recent succession is subdivided into six seismic sequences. Seismic facies mapping of each sequence complemented by information from industry completion reports of 14 wells document a gradual increase in marine influence from latest Oligocene through Middle Miocene time. The increased marine influence reflects the propagation and opening of the southwestern spreading arm of the East Vietnam Sea (South China Sea (East Sea)) combined with rapid subsidence in the Malay-Tho Chu Basin resulting from fast thermal relaxation following Oligocene rifting and amplified by mild fault-controlled subsidence in especially the western part of the area. From the latest Middle Miocene, slowed subsidence and regression occurred in association with uplift in the nearby southwestern East Vietnam Sea. From the latest Miocene, and during the Pliocene and Pleistocene, subsidence rates increased promoting marine conditions towards the East Vietnam Sea in the southeast. Meanwhile, Mekong River avulsion combined with hinterland uplift stimulated fluvial and alluvial deposition in the northern and western parts of the basin. The long-term depositional pattern was controlled primarily by tectonics, drainage evolution and climate. Meanwhile, flood- and delta plain deposits intercalated with stacked fluvial incisions, often filled by estuarine deposits, document short-lived environmental changes most likely controlled by eustatic sea level fluctuations. Such intervals developed during latest Middle Miocene to Pleistocene periods of slow subsidence or fast depositional rates and are interpreted to be the result of substantial eustatic sea level fluctuations.

Distribution and Environmental Impact of Expanded Polystyrene Buoys from Korean Aquaculture Farms

Expanded polystyrene (EPS) buoys, commonly employed in South Korean aquaculture farms, are prone to fragmentation, generating substantial marine debris. The trajectories of EPS buoys dislocated from aquaculture farms were investigated using a Lagrangian particle-tracking model. Daily ocean current data from the 1/12° Hybrid Coordinate Ocean Model analysis and wind data from the 1/4° European Center for Medium-Range Weather Forecasts reanalysis were used as inputs. The particles were released daily, and the initial positions and number of particles were determined based on the usage of EPS buoys. Because EPS buoys are highly buoyant, both wind and ocean currents considerably influence their movement. To account for variations in the buoyancy of these buoys, three experiments were conducted, each considering different levels of windage. The simulation results closely aligned with the observed coastal distribution patterns of the large EPS debris. As the windage increases, the particles exhibit a swifter deviation from their original locations, highlighting the need for effective local management. Moreover, this increased windage affects the distribution patterns in regional seas, reducing the number of particles that flow into the East Sea, while increasing the number of particles that migrate into the Yellow Sea and East China Sea.

Aerosol radiative forcing of forest fires unprecedented in South Korea (2022) captured by Korean geostationary satellites, GK-2A AMI and GK-2B GEMS

The worst forest fires in Korean history broke out on March 4, 2022 and lasted for ten days. In order to monitor the catastrophic forest fires, Geostationary Korea Multi-Purpose Satellite (GK)-2 A Advanced Meteorological Imager (AMI) and GK-2B Geostationary Environment Monitoring Spectrometer (GEMS) data were used in this study. Aerosol optical depth (AOD) irretrievable for the biomass-burning aerosols produced with water vapor classified as could-contaminated, was reconstructed by ultraviolet aerosol index (UVAI). Afterward, aerosol radiative forcing (ARF) at TOA was finally estimated by the correlation of AOD and surface albedo with ARF. Most of the aerosols drifted toward the East Sea by the prevailing westerly winds, and caused a cooling effect on the atmosphere with a maximum daily average radiative forcing of −69.28 Wm-2. Furthermore, the fire-prone conditions for the unprecedented forest fires were discussed in detail as following aspects; 1) the most severe drought caused by a “triple-dip” La Niña; 2) pressure patterns and topographical features that generate strong winds; 3) coniferous forests prone to fires; and 4) increased human activity following the nationwide COVID-19 vaccination. This study demonstrated that the rapid and effective ARF estimation based on the satellite remote sensing can contribute to a better understanding of ARF in the Earth's radiation budget for the global forest fires that will be more frequent, intense, and longer-lasting due to the human-caused climate and environment changes.