Dispersion of passive tracers from long-range HF radar systems along the east coast of Korea

Abstract

We have conducted a virtual surface layer dispersion experiment using the long-range High Frequency radar (HFR) measurements off the east coast of Korea, and investigated the spreading characteristics of the surface waters in the vicinity of two cities, YoungDuk and UlJin for three days of experiments utilizing with random flight model (Markovian stochastic model). The diffusion coefficient was estimated as (Kx , Ky ) = (192, 251) m 2 /s with zonal and meridional dispersions ( σ² u, σ²υ ) = (0.0013, 0.017) m/s and turbulence time scales (Tu , Tv ) = (4, 4) hours derived from exponential fitting of lagged autocorrelation of difference between the HFR-derived and surface drifter-derived currents. During the experiment period, the centroid of the spatial particle distribution moved northward 80 km from the initial position following the East Korea Warm Current (EKWC) and its area became more than 500 times than the initial area. The trajectory and distribution of the surface particles are dependent on the EKWC and diffusion coefficient. Long-term and real-time continuous monitoring system of HFR needs to be combined into national system to improve search and rescue (SAR), and prevent coastal disasters (e.g., oil spill, marine litter) for risk management.