EFFECTS OF INDO-PACIFIC THROUGHFLOW ON THE UPPER TROPICAL PACIFIC ANDINDIAN OCEANS

The dynamics and influence of the connection between the Pacific and I ndian Oceans in the Indonesian Archipelago (PACIO) on the upper tropic al Pacific and Indian Oceans are investigated using a reduced gravity global model. Two different model geometries are used; the first has a n open PACIO region (open case) that permits normal transport, the sec ond has a closed PACIO region (closed case) that allows no transport. The model is forced by either monthly 1980-1989 European Centre for Me dium-Range Weather Forecasting wind stresses or by an imposed Rossby w ave pulse. The average upper layer thickness of the Indian Ocean is si gnificantly greater and more variable because of the influence of PACI O transport. The effect in the Pacific Ocean is much smaller, and ther e appears to be no appreciable effect of PACIO transport on interannua l variability in the eastern tropical Pacific Ocean. RMS differences b etween the open and closed cases show area of low-frequency (> 1/2 yea r) variability over most of the southern Indian Ocean, the western bou ndary of the Indian Ocean, the region of the Mindanao Eddy, and the ea stern equatorial Pacific waveguide. Areas of significant high-frequenc y variability are the East African Coastal Current, the Mindanao Eddy region, the Coral Sea Basin, and in the eastern equatorial Pacific wav eguide. The large effect on the southern Indian Ocean is linked to off -equatorial Rossby waves generated by transport through the PACIO regi on.