New diagnostic sea surface current fields to trace floating algae in the Yellow Sea

The new velocity fields based on the Generalized Ekman (GE) theory to trace floating algae were derived and verified by drifter observations and compared to reanalysis datasets in the Yellow Sea (YS). Two velocity fields using diagnostic approaches and two velocity fields from reanalysis datasets were examined. The results revealed that the diagnostic velocity fields had comparable accuracy to the reanalysis datasets, even locally better. Then, we applied each velocity field to trace green algae, Ulva prolifera, in July 2011 and brown algae, Sargassum horneri, in May 2017 using particle tracking experiments. In addition, drifter trajectories were simulated, and error accumulation speed was estimated for each velocity field. Simulation results using the diagnostic velocity fields consistently showed better agreement with satellite images and in situ observations than those using reanalysis datasets, demonstrating that the diagnostic velocity could be a superior tool for simulating surface-floating substances and organisms. The approach to derive diagnostic velocity fields can be easily applied instead of relying on heavy computing numerical models.