2008 Volume 55 Pages 216-220
In Urauchi Bay of Koshiki Islands, long-period oscillations are observed in early spring. These oscillations are called “Abiki” as is the case with Nagasaki Bay. In this study, numerical calculation of long-period oscillation has been performed by applying the nonlinear shallow-water equations to simulate the oscillation characteristics of Urauchi Bay, which branches into two bays. Numerical results are compared among various types of bays, including I-type, L-type, and T-type bays, the last of which resembles to Urauchi Bay in bay shape. Urauchi Bay shows the second-mode oscillation corresponding to that of T-type bays. The first-mode oscillation can be large especially in Kojima Fishing Port.