Cerovecki, I. ., UCSD, SIO, PORD, La Jolla , USA, icerovec@ucsd.edu
Talley, L. ., UCSD, SIO, PORD, La Jolla , USA, ltalley@ucsd.edu
Mazloff, M. ., MIT, PAOC, Cambridge, USA, mmazloff@MIT.EDU
SUBANTARCTIC MODE WATER AND ANTARCTIC INTERMEDIATE WATER FORMATION
The formation of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) is analyzed using Walin analysis for years 2005 and 2006. Air-sea heat fluxes in the Southern Ocean (SO) are not well known. Therefore we examine several heat flux estimates (NCEP and ECMWF heat flux (HF)products, Coare 3.0 bulk formulae with all NCEP or ECMWF input variables as well as HF from the Southern Ocean State Estimate (SOSE; Mazloff, Heimbach and Wunsch, 2007). For the sea surface density field we use NCEP, ECMWF and Advanced Microwave Scanning Radiometer SST and the best available surface salinity estimates (combination of float data and climatology). SOSE provides its own sea surface density. SAMW is formed on the equatorward flank of the Subantarctic Front by progressive cooling in winter months. Global formation rates obtained from Walin analysis for 80S to 20S peak at 14 deg C, 10 - 11 deg C and 4-5 deg C, corresponding to SAMW in the Atlantic, Indian and Pacific respectively. SOSE formation rates are 3 Sv (3Sv) of 14 deg C water, 1 Sv (2 Sv) of 10 - 11 deg C and 1.5 Sv (2 Sv) 4-5 deg C in years 2005 (2006). Both NCEP HF with NCEP SST and Coare with NCEP input variables have similar peaks as SOSE; Coare and SOSE formation rates are comparable, but NCEP HF formation rates are much higher due to excessively high heat loss during intense cooling episodes. Formation of progressively colder waters is apparent in the monthly analysis for the Atlantic and Pacific.