Analysis of Large Red Tide Bloom off the South East/Japan Sea Using Multi-Satellite Measurements in the Summer of 2013.

Abstract:

A large red tide bloom in the south East/Japan Sea had occurred during the summer of 2013. The bloom had lasted for 51 days from 17^th of July to 5^th of September. During this time period, the red tide dinoflagellate, Cochlodinium polykrikoides was found. C.polykrikoides has been known for preventing oxygen exchanges of fish gills by attaching, leading to perish fishes. Thus, it is important to understand various stages of conditions of red tide developing progress, especially C.polykrikoides, because the fishery industry was damaged due to sporadic and fatal red tide. According to previous research, optimum growth parameters for C.polykrikoides are relatively high temperature and salinity (30-32°C, 30-33psu). We examined causes of red tide bloom using multi-satellite measurements. Research results show that this red tide bloom is related to three processes: enough sunlight, upwelling favorable winds, and warm water. Based on Geostationary Ocean Color Imager (GOCI), cloud presence during August 2013 was smallest during last three years. So the first condition to form such a large bloom is insolation. At the same time, the wind was favorable for the Ekman pumping off the coast of the south East Japan Sea estimated using wind data measured by the Advanced Microwave Scanning Radiometer-EOS (AMSR-E). In addition to offshore Ekman pumping, the onshore upwelling was also observed, which shows relatively cold water on the coastal regions, measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) of Sea Surface Temperature (SST). Accordingly, coastal upwelling supplies nutrients for flourishing C.polykrikoides which is the second condition. The third condition is relatively warm sea surface water of August of 2013 in the region compared to previous years. Furthermore, the Sea Surface Height Anomaly (SSHA) data was also used to understand the current systems around the red tide bloom. In the summer of 2013 at the East/Japan Sea, abundance of insolation, offshore Ekman pumping and coastal upwelling, and warm waters work together contributing to the largest red tide bloom.