Red Tide Monitoring in the Southern Coast of Korea using Geostationary Ocean Color Imager

Abstract

In summer, red tide (Cochlodinium (Margaledinium) polykrikoides) occurs frequently in the southern coast of Korea, which damages aquaculture farms. The phenology of C. polykrikoides shows that the oating to the surface starts in the morning and the surface cell density peaks at around 16:00 KST in Korea coasts. Typical satellite ocean color missions on the polar orbit cannot monitor the bloom since they observe the area once or twice per day. In this research, we present monitoring results of the red tide occurred in summer of 2018 which were conducted by using near-real time chlorophyll-a (Chla) data retrieved from Geostationary Ocean Color Imager (GOCI) which observe the North-East Asian region 8 times per day from 9:15 KST to 16:15 KST. The radiometric bias in the slot borders in GOCI L1B product was mitigated by using the correction of inter-slot radiometric discrepancy using minimum noise fraction transform (CIDUM), after which the Chla concentration over the southern coast was retrieved using two algorithms, the standard ocean color Chla algorithm (OC3) and the red-to-blue band ratio (RBR) algorithm. The monitoring results were analyzed with the ship-based eld observation conducted by National Institute of Fisheries Science (NIFS). The analysis showed that Chla estimation by RBR better captures the Chla variation caused by red tide whereas Chla by OC3 seems to reect total contribution not only from red tide bu