A model for the prediction of harmful algae blooms in the Vietnamese upwelling area

Satellite pictures and in situ observations indicate strong phytoplankton blooms including harmful algae blooms (HABs) during southwest (SW) summer monsoon in the Vietnamese upwelling area. In this period, nutrients are provided by coastal upwelling and by the very high river runoff from the Mekong River. During SW monsoon, in general two circulation patterns exist which allow the prediction of advection and diffusion of HAB patches. A Lagrangian HAB model that is driven by a circulation model and applied to HABs in Vietnamese waters is presented. Advection which is the most complicated part in modelling transport of passive substances is validated with a Lagrangian sediment trap experiment. The model produces realistic results compared to in situ observations and satellite images and might be used for real time forecast in the future.

► HABs occur in the Vietnamese upwelling area only during SW monsoon.
► The summer circulation can be desribed by two different circulation fields only.
► The predictability of HABs is important for coastal protection.