GOCI 자료를 이용한 서해안 갈조 탐지 연구

Abstract

A large amount of the Sargassum horneri (S.horneri) came to the Yellow Sea in 2015. This resulted in a scarcity of oxygen in the ocean, which in turn caused the deaths of many fish and other marine organisms. Not only did the arrival of the S.horneri caused harm to the inhabitants but it was also responsible for the insufferable stench. Since the S.horneri is a nuisance to deal with, it is crucial to detect it before it inflicts more damage. This study presents the results of S.horneri detection using Geostationary Ocean Color Imager (GOCI) data during the period between January and June in 2015. GOCI data are one of the best tools for detecting the S.horneri because it collects data 8 times per day. The data can also be used to observe the temporal variations of the S.horneri distribution in the ocean frequently. We first used normalized difference vegetation index (NDVI) using 660nm and 745nm of GOCI to detect all floating vegetation algae. With NDVI only, however, S.horneri detection is challenging in turbid waters because NDVI is elevated by the high NIR signals due to mineral particles in turbid waters. So, in the next step, we employed an anomaly detection technique to increase the detection rate of S.horneri both in clear and turbid waters. Finally, we tried to differentiate between S.horneri and other floating algae and estimated its coverage within a pixel.