• Asian Journal of Atmospheric Environment
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• v.11 no.2
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• pp.71-78
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• 2017

Monthly characteristics of rainwater chemistry at a coastal site in southwestern Japan were examined based on an eight year record. In the period November-May when rain was mainly caused by cyclones, the monthly mean concentrations of $nss-{SO_4}^{2-}$, ${NO_3}^-$, ${NH_4}^+$, $nss-Ca^{2+}$, $Na^+$ and $Cl^-$ over the eight years were 25.1-57.8, 9.9-25.0, 11.3-31.4, 5.5-18.7, 24.2-154.9 and $30.0-178.5{\mu}eq\;L^{-1}$, respectively. In June and July when rain was mainly caused by stationary fronts, i.e. Meiyu fronts, the concentrations were 14.4-20.7, 7.2-9.5, 7.7-12.9, 4.1-6.8, 21.7-33.6 and $26.4-40.5{\mu}eq\;L^{-1}$, respectively. In August and September when typhoons contributed substantial rainfall, the respective concentrations of $Na^+$ and $Cl^-$ were as high as 97.7-105.3 and $116.8-122.9{\mu}eq\;L^{-1}$, while the concentrations of other ions were low. These results indicate a large variation of monthly rainwater chemistry, which is basically dependent on the synoptic weather patterns causing rain. From later autumn to early spring, rain contains ions in high concentration and large variation ranges. In the Meiyu season, rain contains less ions which vary in a range much smaller than that in later autumnearly spring. In summer and autumn, the concentrations are low, except $Na^+$ and $Cl^-$ which can be large due to typhoons' contribution.

• Ocean and Polar Research
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• v.32 no.2
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• pp.97-111
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• 2010

Phytoplankton production is affected by various physico-chemical factors of environment. However, one of the most critical factors generally accepted as controlling primary production of phytoplankton is nutrients. It has recently been found that the succession of phytoplankton groups and species are closely related to the chemical properties of ambient water including nutrient limitation and their ratios. In Jangmok Bay, silicate and nitrate are primarily supplied by rainfall, while phosphate and ammonia are supplied by wind stress. Typhoons are associated with rainfall and strong wind stress, and when typhoons pass through the South Sea, such events may induce phytoplankton blooms. When nutrients were supplied by heavy rainfalls during the rainy season and by summer typhoons in Jangmok Bay, the dominant taxa among the phytoplankton groups were found to change successively with time. The dominant taxon was changed from diatoms to flagellates immediately after the episodic seasonal events, but returned to diatoms within 3~10 days. Pseudo-nitzschia spp. were dominant mainly in the presence of low phosphate levels during the first of the survey which included the rainy season, while Skeletonema costatum was dominant when phosphate concentrations were high due to the strong wind stress during the latter half of the survey as a result of the typhoon. The competition between S. costatum and Chaetoceros spp. appeared to be regulated by the silicate concentration. S. costatum preferred high silicate and phosphate concentrations; however, Chaetoceros spp. were able to endure low silicate concentrations. These results implied that, in coastal ecosystems, the input patterns of each nutrient supplied by rainfall and/or wind stress appeared to contribute to the summer succession of phytoplankton groups and species.

• Wind and Structures
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• v.26 no.1
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• pp.11-24
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• 2018

Full-scale measurements of wind action on the open roof structure of the WuXi grand theater, which is composed of eight large-span free-form leaf-shaped space trusses with the largest span of 76.79 m, were conducted during the passage of Typhoons HaiKui and SuLi. The wind pressure field data were continuously and simultaneously monitored using a wind pressure monitoring system installed on the roof structure during the typhoons. A detailed analysis of the field data was performed to investigate the characteristics of the fluctuating wind pressure on the open roof, such as the wind pressure spectrum, spatial correlation coefficients, peak wind pressures and non-Gaussian wind pressure characteristics, under typhoon conditions. Three classical methods were used to calculate the peak factors of the wind pressure on the open roof, and the suggested design method and peak factors were given. The non-Gaussianity of the wind pressure was discussed in terms of the third and fourth statistical moments of the measured wind pressure, and the corresponding indication of the non-Gaussianity on the open roof was proposed. The result shows that there were large pulses in the time-histories of the measured wind pressure on Roof A2 in the field. The spatial correlation of the wind pressures on roof A2 between the upper surface and lower surface is very weak. When the skewness is larger than 0.3 and the kurtosis is larger than 3.7, the wind pressure time series on roof A2 can be taken as a non-Gaussian distribution, and the other series can be taken as a Gaussian distribution.

• Journal of Korea Water Resources Association
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• v.47 no.4
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• pp.385-396
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• 2014

Lately, more frequent typhoons cause extensive flood and wind damage throughout the summer season. In this respect, this study aims to develop a probabilistic clustering model that uses both typhoon genesis location and trajectories. The proposed model was applied to the 197 typhoon events that made landfall in the Korean peninsula from 1951 to 2012. We evaluate the performance of the proposed clustering model through a simulation study based on synthetic typhoon trajectories. The seven distinguished clusters for typhoons affecting Korean peninsula were identified. It was found that most of typhoon genesis originated from a remote position ($10^{\circ}{\sim}20^{\circ}N$, $120^{\circ}{\sim}150^{\circ}E$) near the Equator. Cluster, type B can be regarded as a major track due to the fact that its frequency is approximately about 25.4% out of 197 events and its direct association with strong positive rainfall anomalies.

• Journal of Fisheries and Marine Sciences Education
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• v.18 no.2
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• pp.137-149
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• 2006

The typhoon, heavy rain, blizzard, storm and heavy snowfall had the main caused of natural disasters occurred in Korea from 1993 to 2002. Among them, typhoon has responsible for biggest disaster, recording about 47.4% of total economic damage. Typhoons concentrated mostly in the months from June to October. The average occurrence number in those months ranged from 3.9 to 5.5 based on 30 years of record(1971-2000). However, the numbers increased from 4.0 to 6.2 during the most recent 10 years(1991-2000). Jeju province, among others in Korea, was most frequently affected by typhoon which occurred 23 times during the period of 1991-2000. Typhoons which occurred from July to early August have passed mostly through the west of Jeju, whereas, those of late August to September have passed through the center and eastern sea area of Jeju. The typhoons 'Ramasun' and 'Rusa' caused severe damage in Jeju area in September 2003 and the surge heights were +39cm and +77cm, respectively. The main cause of the damage was surge height which was highly associated with the tidal phase at the time of typhoon passage. The damage caused by typhoon on the aquaculture, fishing boat and harbor cosatline wall around Jeju Island which was amounted to be 417 billion won(\) during the recent 3 years(2002-2004)

• 한국해양학회지
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• v.6 no.2
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• pp.92-98
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• 1971

Storm surges caused by typhoon Billie, 28 Aug. ∼ 2 Sep. 1970, on the west and south coasts of Korea are studied with the tidal data. Tracks and frequencies of the typhoons which affected the Korean peninsula and the yearly maximum tidal deviation at tide stations for the past twelve years are also reviewed. It is assumed that most of the typhoons affecting the Korea peninsula cause variations of sea level along almost all of the coast of Korea. Maximum storm surges at each tide station on the south coast appeared to be caused by typhoons during the summer, and by the north westerly monsoon and extraordinary cyclones on the west coast during spring and winter. In the coastal waters of the west coast where depths are shallower and the bottom configuration is flat, sea level variation is mostly caused by atmospheric pressure and wind effect. When a typhoon travels as in case of typhoon Billie, sea level ascends generally on the south coast and it descends on the west coast before the typhoon approaches near to the coasts. Considering the large tidal range on the western and southern coasts, it is assumed that the extraordinary destructive surges can be occurred when the tide is high water. Reviewing the monthly mean sea level variations on the each coast, hazards to be caused by storm surges can more fluently occur during the summer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.5385-5392
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• 2014

Super typhoons develop as a result of meteorological changes. In 2012, Typhoons Bolaven and Denba reached Korea. The maximum instantaneous wind speed of the typhoons reached 60 m/sec. Harbor structures including sofa block sustained damage and loss by the abnormally high waves. In Korea, tetrapod blocks were installed the most for wave dissipating. Nevertheless, a structural evaluation of the tetrapod block has not been performed. This study examined the structural mechanism and weakness part of the tetrapod block under a range of boundary conditions. The block has weakness against a tensile force because it is plain concrete. The joint part of the legs is the most vulnerable to tensile stress. The weakest part can be reduced if the joint part is reinforced as a hunch.

• Journal of the Korean earth science society
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• v.28 no.5
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• pp.585-597
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• 2007

The characteristics of the rainfall events on the Korean peninsula have been investigated by means of regional and global observational data collected from 1954 to 2004 with an emphasis on extreme cases $80\;mm\;day^{-1}$. According to our analysis, long-term annual rainfall anomalies show an increasing trend. This trend is pronounced in the month of August, when both the amount of monthly rainfall and the frequency of extreme events increase significantly. Composite maps on August during the 8 wet years reveal warm SST anomalies over the eastern Philippine Sea which are associated with enhanced convection and vertical motion and intensified positive SLP over central Eurasia during August. The rainfall pattern suggests that the most significant increase in moisture supply over the southern parts of China and Korea in August is associated with positive SLP changes over Eurasia and negative SLP changes over the subtropical western Pacific off the east coast of south China. The frequent generation of typhoons over the warm eastern Philippine Sea and their tracks appear to influence the extreme rainfall events in Korea during the month of August. The typhoons in August mainly passed the western coast of Korea, resulting in the frequent occurrence of extreme rainfall events in this region. Furthermore, anomalous cyclonic circulations over the eastern Philippine Sea also promoted the generation of tropical cyclones. The position of pressure systems - positive SLP over Eurasia and negative SLP over the subtropical Pacific - in turn provided a pathway for typhoons. The moisture is then effectively transported further north toward Korea and east toward the southern parts of China during the extreme rainfall period.

• Journal of Ocean Engineering and Technology
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• v.20 no.3 s.70
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• pp.37-44
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• 2006

Each year, the coast of Busan is badly damaged, due to storm surge. The damages are greatly dependent upon the local peculiarities of the region in which the storm surge occurs. So, in order to prevent/reduce recurrence of the disaster due to the storm surge, it is very important to investigate the fluctuation characteristics of the storm surge height, related to the local peculiarities at each coastal area in which the occurrence of the disaster is expected. In this paper, using the numerical model, the storm surge was simulated to examine its fluctuation characteristics at the coast of Busan Typhoons of Sarah (5914), Thelma (8705) and Maemi (0314), which caused terrible damage to the coastal areas alongthe coast of Busan in the past, were taken as an object of the storm surge simulations. Moreover, the storm surge due to virtual typhoons, which were combined with the characteristics of each proposed typhoon (Maemi, Sarah, Thelma), compared to the travel routes of other typhoons, was predicted. As expected, the results revealed that the storm surge heights are enhanced at the coastal region with the concavity like a long-shaped bay. Also, the storm surge heights, due to each typhoon, were compared and discussed at major points along the coast of Busan, related to the local peculiarities, as well as the characteristics and the travel route of the typhoon.

• Journal of Ocean Engineering and Technology
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• v.20 no.3 s.70
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• pp.45-53
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• 2006

Each year, the south coast of Korea is badly damaged from storm surge. The damages are greatly dependent upon the local peculiarities of the region where the storm surge occurs. So, in order to prevent/reduce recurrence of the disaster, it is very important to investigate the fluctuation characteristics of the storm surge height, related to the local peculiarities at each coastal area where occurrence of the disaster is expected. In this paper, using the numerical model, the storm surge was simulated to examine its fluctuation characteristics at the Gyeongnam coast (southeast coast of Korea). Typhoons of Sarah (5914), Thelma (8705) and Maemi (0314), which caused terrible damage to the coastal area in the southeast coast of Korea in the past, were used forstorm surge simulations. Moreover, the storm surge due to virtual typhoons, which were combined the characteristics of each proposed typhoons (Maemi, Sarah, Thelma)with the travel route of other typhoon, was predicted. As expected, the results revealed that the storm surge heights are enhanced at the coastal regions with the concavity like a long-shaped bay. Also, the storm surge heights, due to each typhoon, were compared and discussed at major points along the Gyeongnam coast, related to the local peculiarities, as well as the characteristics and the travel route of typhoon.