Underwater Visibility Changes Due to Turbidity associated with Typhoon

Title
Underwater Visibility Changes Due to Turbidity associated with Typhoon
Author(s)
Cho, Jin Hyung; Son, Young Baek; Shin, Dong-Hyeok; Kum, Byung-Cheol; Moh, Taejun; Jang, Seok; Lee, Seung Yong; Lim, Dong Gil; Jung, Seom Kyu
KIOST Author(s)
Cho, Jin Hyung(조진형)Son, Young Baek(손영백)Shin, Dong Hyeok(신동혁)Kum, Byung Cheol(금병철)Jang, Seok(장석)Lee, Seung Yong(이승용)Lim, Dong Gil(임동길)Jung, Seom Kyu(정섬규)
Alternative Author(s)
조진형; 손영백; 신동혁; 금병철; 모태준; 장석; 이승용; 임동길; 정섬규
Publication Year
2020-07-22
Abstract
Changes of visibility in the water column off the southern coast of Korea due to the effects of Typhoon Soulik (Aug. 22–23, 2018; 955 hPa; maximum wind speed, 40 m/s) were investigated. The beam attenuation coefficient (BAC) was measured using a transmissometer (C-Star; Wet Labs, Inc.), and visibility range was calculated using the conversion method employed by the US Navy. For comparison and verification of the data, a conductivity–depth–temperature (CTD) probe (SBE19 Plus; Sea-Bird Scientific) equipped with optical backscatter and fluorescence sensors was deployed simultaneously with the transmissometer. The Secchi depth was also estimated during each cast to improve accuracy. The Secchi depth deviated by up to 20% from the calculated visibility range. Additionally, during continuous observation of BAC from the seafloor upward, a light source (color temperature: 6,500 K) was installed on a 5-m bar with length markings, and a video camera recorded changes in visibility. Daily Geostationary Ocean Color Imager (GOCI) satellite data were used to identify changes in surface visibility in the study area.
Before the typhoon, the visibility in the water column was in the range 25–30 m. Near the seafloor, visibility approached 0 m due to a 3–6-m turbidity current. The visibility distance was significantly shorter in the bottom layers based on video images. Four days after Typhoon Soulik had passed over the Korean Peninsula, the visibility was in the range 2.6–9.0 m in the upper layers of the water column, increasing gradually to 11 m in the middle layers. The size of the turbid bottom current did not differ significantly between observations before and after the typhoon. Surface visibility calculated from satellite data also decreased by 20–30% compared to that before the typhoon.
URI
https://sciwatch.kiost.ac.kr/handle/2020.kiost/32871
Bibliographic Citation
2020년도 한국해양과학기술협의회 공동학술대회 (한국해양학회), 2020
Publisher
한국해양과학기술협의회
Type
Conference
Language
Korean
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