Title

A Three-Dimensional Regional Model of the Indonesian Seas Circulation

Date of Award

2007

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Marine Science

First Advisor

Vladimir Kamenkovich

Advisor Department

Marine Science

Abstract

This study describes the ocean circulation of the Indonesian Seas based on results using a 3D regional model. The model has four open ports to simulate inflow of North Pacific Water from the Mindanao Current, inflow of South Pacific Water from the New Guinea Coastal Current, outflow to the Pacific Ocean due to the North Equatorial Counter Current, and outflow to the Indian Ocean due to the Indonesian Throughflow. Four experiments are discussed: seasonally varying and annual mean transports and port normal velocities both with and without local winds. All experiments are totally spun up after 10 years. This analysis uses data from the post spin up period only. The influence of bottom topography on the formation of temperature and salinity distributions is considered by following the three major routes of flow of North Pacific and South Pacific Water through the Indonesian Seas. There are no substantial structural changes of potential temperature and salinity distributions between seasons, though values of some parameters of temperature and salinity distributions (e.g., magnitudes of maxima and minima) can change. It is shown that the main structure of the observed distributions of temperature and salinity is satisfactorily displayed throughout the entire model domain. The calculated transports of internal energy (heat) and salt mass through the Lombok and Ombai Straits, and Timor Passage in August and February are in reasonable agreement with published observed and simulated data. Aspects of turbulence and mixing in the Indonesian Seas are presented and discussed. The results are based on the Mellor-Yamada 2.5 turbulence parameterization model. Though the importance of mixing in the Indonesian Seas has been widely acknowledged, very few observations are available and there have been no model studies of mixing or turbulent diffusion in the region. The study is focused on turbulent diffusion and turbulent kinetic energy in the upper mixed layer, the thermocline and in deep water near topographic features. Very large turbulent kinetic energies and vertical turbulent diffusivities are seen around topography and are important for the deep overflows found in the region. Large turbulent energies and diffusivities found in the thermocline are important for the diffusion of temperature and salinity signatures found in the Indonesian Seas. Monsoon winds and local currents lead to large diffusivities in the upper mixed layer. (Abstract shortened by UMI.)