KINETIC ENERGY DYNAMICS ASSOCIATED WITH BAROCLINIC AND BAROTROPIC MOTIONS IN TOKYO BAY

Abstract

 This study presents effects of barotropic/baroclinic, tidal/non-tidal motions and their frequency characteristics in the inner part of Tokyo Bay using long-term monitoring data. Observed flows are divided into tidal and non-tidal currents, and these components are decomposed into barotropic and baroclinic currents. Results showed that the non-tidal baroclinic component dominate in the total kinetic energy and is enhanced in summer. The relationship between the stratification and the kinetic energy of the non-tidal baroclinic component shows a clear positive correlation. This indicates that the non-tidal baroclinic component in the shallow inner bay is caused by enhanced estuarine circulations due to summer stratification. In addition, the four components are decomposed into long-period and short-period components (low and high frequencies, respectively) with a cut-off period of 36 hours. The short-period component dominates in the nontidal baroclinic component, and the long-period component dominates in the non-tidal barotropic component in the inner bay. The long-period non-tidal barotropic component is explained by low frequency winds.