Increase of South Pacific eastern subtropical mode water under global warming

摘要

The response of South Pacific Eastern Subtropical Mode Water (SPESTMW) to global warming is investigated by comparing solutions from a set of Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) coupled models between a present-day climate and a future, warmer climate. Under the warmer climate scenario, the SPESTMW extends southwestward and is significantly increased in volume. This is because all the local surface forcing mechanisms (i.e., wind stress, heat and freshwater fluxes) in the eastern subtropical South Pacific tends to de-stratify the upper ocean and thus deepen the mixed layer. Further, a suite of process-oriented experiments with an ocean general circulation model suggest that it is the intensified southeast trade winds under the warmer climate that promotes more heat flux from the ocean into the atmosphere that then results in a deepening of the mixed layer in the eastern subtropics of the South Pacific.