Investigating Optical Properties of Red Tide in a Turbid Coastal Area Near Tongyeong, South Korea

Typhoons can often cause inundation in lower coastal cities by inducing strong surges and waves. Being affected by typhoon annually, the coastal cities in South Korea are very vulnerable to typhoons. In 2016, a typhoon ‘CHABA’, with a maximum 10 min sustained wind speed of about 50 m/s and a minimum central pressure of 905 hPa, hit South Korea, suffering tremendous damage. In particular, ‘CHABA’-induced coastal inundation resulted in serious damage to the coastal area of Busan where a lot of high-rise buildings and residential areas are concentrated, and was caused by the combined effect of tide, surge, and wave. The typhoon-induced surge raised sea levels during high tide, and the strong wave with a long period of more than 10 s eventually led to the coastal inundation at the same time. The present research focuses a numerical downscaling considering the effects of tide, surge and wave for coastal inundation induced by Typhoon ‘CHABA’. This downscaling approach applied several numerical models, which are the Weather Research and Forecasting model (WRF) for typhoon simulation, the Finite Volume Community Ocean Model (FVCOM) for tide and surge simulation, and the Simulating WAve Nearshore (SWAN) for wave simulation. In a domain covering the Korean Peninsula, typhoon-induced surges and waves were simulated applying the results simulated by WRF as meteorological conditions. In the downscaled domain ranged near the coastal area of Busan, the coastal inundation was simulated blending a storm tide height and an irregular wave height obtained from the domain, in which each height has 1 s interval. The irregular wave height was calculated using the significant wave height and peak period. Through this downscaling study, the impact of storm tide and wave on coastal inundation was estimated.

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Ecohab: Hyperspectral Optical Properties of Red-Tide Blooms

10.21236/ada629760 ◽

1999 ◽

Author(s):

Helmut Maske ◽

James L. Mueller ◽

Charles C. Trees

Keyword(s):

Optical Properties ◽

Red Tide

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Optical properties of chromophoric and fluorescent dissolved organic matter in the coastal Jeju Island: Impact of the anthropogenic sources

10.5194/egusphere-egu2020-20832 ◽

2020 ◽

Author(s):

Jeonghyun Kim ◽

Yeseul Kim ◽

Tae-Hoon Kim ◽

Sung Eun Park ◽

Dong-Jin Kang ◽

...

Keyword(s):

Organic Matter ◽

Optical Properties ◽

Absorption Coefficient ◽

Coastal Area ◽

Sewage Treatment ◽

Principal Component ◽

Point Sources ◽

Jeju Island ◽

Anthropogenic Sources ◽

Fluorescent Dissolved Organic Matter

The hydrological properties (temperature, salinity, pH, and dissolved oxygen), dissolved organic carbon (DOC) and nitrogen (DON), and optical absorption and fluorescence signals were measured in Jeju Island, Korea, during 2016&#8211;2018, especially in potential point-sources (e.g. coastal aquafarms, a sewage treatment facility, and coastal artesian springs). The water samples were filtered through 0.2 &#956;m polycarbonate syringe filters. The optical analysis was conducted using a spectrophotometer (Aqualog, Horiba, USA). Absorbance spectra were converted into the absorption coefficient, and fluorescence intensities were conducted by the parallel factor analysis (PARAFAC) model. The fluorescent components were compared with previous studies through the web-based OpenFluor database.The absorption coefficient at 350 nm ranged from 0.05 to 7.63 m &#8722;1, and it was up to 150 times higher near the point-sources than in the normal coastal ocean. In addition, a350 was observed to be exponentially increased as the reduced distance from the aquafarm outlet. Similarly, the concentration of DOC was 89 &#177; 29 &#956;M near the point-sources and 78 &#177; 13 &#956;M in the normal coastal area. They were also observed to be high fluorescence near the point-sources. Principal component analysis (PCA) was applied to illustrate the relationship among the five PARAFAC components, DOC, DON, a350, and fluorescence indexes (HIX, BIX, FI, TC ratio, and RI). The PCA results separated allochthonous, terrestrial components from autochthonous, microbial components, as explained 71.3% of the variance in the data. Based on the HIX (1.26 &#8211; 55.70) and BIX (0.52 &#8211; 2.87) values in this study, the organic matter around the coastal Jeju Island seem to be highly affected by the coastal groundwater. Here, we used multiple optical properties of organic matter near the coastal area to identify the key factor contributing its distribution and water qualities and to determine the significant influence of the point-sources.

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Comparison of optical characteristics in non-red tide and red tide areas in the South Sea of Korea

10.5194/egusphere-egu2020-6605 ◽

2020 ◽

Author(s):

Eunkyung Lee ◽

Jeong-Eon Moon ◽

Young-Je Park ◽

Tai-Hyun Han

Keyword(s):

Remote Sensing ◽

Optical Properties ◽

Korean Peninsula ◽

Analytical Methods ◽

Field Data ◽

Red Tide ◽

Optical Characteristics ◽

Cochlodinium Polykrikoides ◽

Southern Coast ◽

Remote Sensing Reflectance

Red tide, which occurs off the southern coast of the Korean Peninsula, is a maritime phenomenon that usually occurs between June and September every year, mostly by Cochlodinium polykrikoides single species. There are very few studies using the analytical methods of the inherent and apparent optical properties for these red tide. Ahn et al.(2009) analyzed the inherent optical properties of 26 species of red tide organisms occurring off the southern coast of the Korean Peninsula. Kim et al.(2016) distinguished the optical characteristics for Cochlodinium polykrikoides using field data and Hydrolight simulator. Using these analytical methods, we will understand the ocean optical properties of red tide and use the remote sensing reflectance simulator in the future to produce the input data necessary for developing the red tide analysis technology based on machine learning. Therefore, in this study, as an initial analysis, we will compare the in-situ data of red tide and non-red tide waters off the southern coast of the Korean Peninsula in September 2014 and August 2017 to identify differences in the spectral form and compare the ability of the remote sensing reflectance spectrum with the field data using a remote sensing reflectance simulator.

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