Sea Fog Analysis Using Jeju Island GNSS Observables to Prevent Marine Accidents

Ha, J.; Lee, J.K., and Park, S. J., 2019. Sea fog analysis using Jeju Island GNSS observables to prevent marine accidents. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 346-350. Coconut Creek (Florida), ISSN 0749-0208.Sea fog leads to poor visibility for ship navigation, and thus is a major cause of severe marine accidents such as groundings and collisions between ships and unmapped objects such as icebergs. In this study, a temporary GNSS observatory was installed at the Gosan weather station on Jeju Island, the largest island in South Korea and located along its busiest shipping lanes, to determine the feasibility of using GNSS measurements to observe fog. In Korea, the greatest amount of sea fog occurs between April and September. In the South Sea where Jeju Island is located, the heaviest fog occurs around July and August. Accordingly, from the 11th to the 14th of August 2009, the temporary GNSS observatory was used to collect data describing the perceptible water vapor and an automatic weather station was used to measure the mixing ratio in the area of Jeju Island. When analyzed and compared to radiosonde and other meteorological data, this data indicated that the GNSS-measured perceptible water tended to increase prior to the occurrence of precipitation and fog, while conversely the AWS-measured mixing ratio tended to decrease. When fog occurred prior to rain, the GNSS-measured perceptible water decreased, demonstrating that it reacts sensitively to the occurrence of fog. It was also found that the increasing trend of the AWS-measured mixing ratio was somewhat delayed prior to the occurrence fog, indicating a close relationship between the two.