A numerical simulation of red tide formation

A numerical simulation of the formation of Gymnodinium mikimotoi red tides at Suo-Nada and Iyo-Nada, the western part of the Seto Inland Sea, Japan, in July 1985 is attempted using the Euler-Lagrange method with four-dimensional assimilation model including biological processes. The calculated results reproduce well the formation of red tides in the field. It is suggested from the results of the numerical experiments that the intake of ammonium at night by G. mikimotoi and the physical accumulation of cells by advection play very important roles in the formation of red tides at Suo-Nada.