Qian Song

National Oceanic and Atmospheric Administration

The Indonesian Throughflow (ITF) is an important component of the global thermohaline circulation, and regionally it provides an essential pathway for the freshwater and heat transfer from the western Pacific to the Indian Ocean. The variability of the ITF, therefore, affects not only the heat and freshwater budgets of the Indo-Pacific basin, but also the global climate. Thus, it is critical for global climate models to simulate the ITF transport and water mass properties correctly to address climate change issues. However, the extremely complex topography of the Indonesian Seas imposes substantial challenge to numerical modelers, and the skills of those global climate models in reproducing the ITF characteristics are largely unknown. In addition, because of the sparseness of observations on the ITF, there is need to study the ITF variabilities in numerical models, which has been done mostly in ocean-only models.
This proposed study has two objectives: (1) assess the coupled model simulations of the transport and water mass properties of the ITF by comparing the model simulations with observations (which include mooring measurements, XBT, CTD measurements from ARLINDO project) and intercomparing among models; and (2) investigate the variabilities, both natural variabilities and those forced by greenhouse gases, of the ITF transport in the coupled models on various time scales and their relationship with large scale wind fields and phenomena such as ENSO. The model outputs we need are: (1) temperature, salinity, horizontal velocities in eastern Indian Ocean and western Pacific Ocean; (2) sea surface temperature of the Pacific and Indian Oceans; (3) near surface wind fields. This study will not only provide scientific results for the IPCC report, but also serve the general interest of the scientific community in the ITF variabilities in coupled climate models.