Contribution of equatorial Pacific winds to southern tropical Indian OceanRossby waves

Westward propagating features, identified as Rossby waves, have been observ ed and modeled in the southern tropical Indian Ocean (STIO) between 10 degr ees and 30 degreesS. These STIO Rossby waves, which have broad zonal and me ridional extents, could interact with the westward flowing South Equatorial Current (SEC) as well as coastal currents on the south shore of Java (the South Java Current) and along the western shore of Australia (the Leeuwin C urrent). Previous work has attributed these waves to variations in wind str ess along the west coast of. Australia, Ekman pumping in the STIO interior, and a combination of both. This study investigates the importance of a thi rd factor: remotely forced coastal Kelvin waves. Observations show that cha nges in wind stress curl in the eastern equatorial Pacific create annual up welling and downwelling Rossby waves. Numerical model results confirm previ ous studies that demonstrate these waves, upon reaching the western boundar y of the Pacific, create poleward propagating coastal Kelvin waves along th e western shore of the Irian Jaya/Australia land mass. Direct observations of annual sea level variations along the northwest coast of Australia show a phase lag from the northernmost station to the southernmost that is not e xplained by direct wind forcing, suggesting that this signal is propagating from the Indonesian seas. It is shown in this work that when these waves r each the Indian Ocean, they are in phase with the local Ekman forcing and e nhance the STIO Rossby waves. Tn the model the signal from the equatorial P acific accounts for almost 80% of the energy of the STIO Rossby wave near t he coast of Australia and 10% of the energy offshore.