Influence of Low-Frequency Indonesian Throughflow Transport on Temperatures in the Indian Ocean in a Coupled Model

Abstract

The relationship between 3- and 10-yr variability in Indian Ocean temperatures and Indonesian throughflow (ITF) volume transport is examined using results from a 300-yr integration of the coupled NCAR Parallel Climate Model (PCM). Correlation and regression analyses are used with physical reasoning to estimate the relative contributions of changes in ITF volume transport and Indian Ocean surface atmospheric forcing in determining low-frequency temperature variations in the Indian Ocean. In the PCM, low-frequency variations in ITF transport are small, 2 Sv (1 Sv ≡ 106 m3 s?1), and have a minimal impact on sea surface temperatures (SSTs). Most of the low-frequency variance in Indian Ocean temperature (rms > 0.5°C) occurs in the upper thermocline (75?100 m). These variations largely reflect concurrent atmospheric forcing; ITF-induced temperature variability at this depth is limited to the outflow region between Java and Australia extending westward along a band between 10° and 15°S.