Sea ice formation effect on deep Pacific overturnign and cross equatorial mass flux associated with Indo-Pacific throughflow

摘要

Salt ejection from sea ice due to sea ice formation during Antarctic winter is an important component of Antarctic Bottom Water, and fresh water release from sea ice melting during Antarctic summer is a source of fresh water tongue of Antarctic summer is a source of fresh water tongue of Antarctic INtermediate Water. The former is a source of deep Pacific overturning, and the latter plays an essential role in confluent region of the western tropical Pacific where intrinsic oceanic processes take place. We use the ocean isopycnal ocean general circulation (OPYC) model, which is based on the primitive equations with a prognostic free surface, to study the effect of Antarctic sea ice formation on Antractic Intermediate water and Antarctic Bottomwater formation. We show that the even small change of salt ejection from Antarctic sea ice cause notiable cross equatorial mass flux anomalies and even Indo-Pacific throughflow anamoalies. Since ocean-only models use atmospheric flux climatolgy that is usually complied as monthly averaged and gridded on 2 degree bins, models always underestimate Antarctic sea ice formation in present ocen-only GCM runs.