Holte, J.W. and L. D. Talley, 2006. Examining Subantarctic Mode Water Formation with a new Method for Finding Mixed Layer Depths and ARGO.

A new method for finding the mixed layer depth (MLD) of individual ocean profiles was developed to investigate the formation of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) using ARGO float data. The method seeks to improve upon threshold methods by incorporating aspects of threshold methods to a scheme that models the general shape of each profile and searches for physical features to identify the MLD. The new temperature and density algorithms were developed by examining profiles from all oceans. The temperature algorithm offers an improvement over its threshold counterpart; the temperature algorithm's MLDs nearly match those of the density methods. Confined to 3067 ARGO profiles from the Southeast Pacific and the Southwest Atlantic Oceans, the temperature algorithm finds shallower MLDs than a temperature threshold using Montegut et al.'s (2004) criterion for 63% of the profiles. The Southeast Pacific and the Southwest Atlantic Oceans are two regions of SAMW formation, apparent as deep mixed layers immediately north of the Subantarctic Front (SAF). With the density algorithm we find that the deepest MLDs reach 500 dbar and occur north of the Orsi et al. (1995) mean SAF in the Southeastern Pacific Ocean. The deepest MLDs typically occur in August and September and have densities of approximately 27 kg m(-3), salinities of 34.1-34.2 psu, and temperatures of 4-5 C. Within the Pacific study region, the deepest winter mixed layers occur at 57 S and are concurrent with the salinity minimum outcropping, a signature of AAIW. Preliminary results of applying the algorithm to profiles collected during the Winter 2005 AAIW cruise generally confirm these findings.

DE: 4504 Air/sea interactions (0312, 3339)
DE: 4572 Upper ocean and mixed layer processes
DE: 4594 Instruments and techniques
SC: Ocean Sciences [OS]
MN: 2006 Fall Meeting