SEASONAL VARIABILITY OF WATER EXCHANGE BETWEEN THE PACIFIC AND INDIAN OCEANS ACCORDING TO ARGO DATA AND NUMERICAL MODELING

Abstract

Circulation associated with the Indonesian Troughflow (ITF) is studied using the Argo-based Model for Investigation of the Global Ocean (AMIGO). The model consists of a block for variational interpolation to a regular grid of Argo floats data and a block for model hydrodynamic adjustment of variationally interpolated fields. The seasonal and monthly mean temperature, salinity and velocity fields were calculate for the period of 2005–2014 using such an aproach. The mean ITF mass, heat, and salt transports over a period of 2005–2014 based on the AMIGO data is diagnosed as 15.2 ± 2.3 Sv. The maximum value of mass transport was diagnosed in August as 18.8 ± 1.4 Sv, the minimum value of 11.8 ± 2.1 Sv was found in January. The detailed analisys of seasonal variability of the mass transport through the Makassar Strait (Makassar throughflow or MT), the primary inflow path of Pacific water into the Indonesian Seas, were performed. The maximum and minimum values of MT were also diagnosed in August and January as 22.1 ± 1.2 Sv and 9.8 ± 2.1 Sv respectively. It was found significant changes in the MT sutface layer flow during boreal winter (with total reverse in January) associated with the intrusion of the low surface salinity waters of the Java and South China Seas. These modeling results agree very well with the direct velocity measurements.