Mixing and remineralization in waters detrained from the surface into Subantarctic Mode Water and Antarctic Intermediate Water in the southeastern Pacific

TitleMixing and remineralization in waters detrained from the surface into Subantarctic Mode Water and Antarctic Intermediate Water in the southeastern Pacific
Publication TypeJournal Article
Year of Publication2014
AuthorsCarter BR, Talley LD, Dickson AG
JournalJournal of Geophysical Research-Oceans
Volume119
Pagination4001-4028
Date Published2014/06
Type of ArticleArticle
ISBN Number2169-9275
Accession NumberWOS:000340414800043
Keywordsanthropogenic co2; carbonic-acid; global ocean; isopycnal surfaces; marine plankton; north-atlantic; particle fluxes; redfield ratios; sediment traps; southern-ocean
Abstract

A hydrographic data set collected in the region and season of Subantarctic Mode Water and Antarctic Intermediate Water (SAMW and AAIW) formation in the southeastern Pacific allows us to estimate the preformed properties of surface water detrained into these water masses from deep mixed layers north of the Subantarctic Front and Antarctic Surface Water south of the front. Using 10 measured seawater properties, we estimate: the fractions of SAMW/AAIW that originate as surface source waters, as well as fractions that mix into these water masses from subtropical thermocline water above and Upper Circumpolar Deep Water below the subducted SAMW/AAIW; ages associated with the detrained surface water; and remineralization and dissolution rates and ratios. The mixing patterns imply that cabbeling can account for similar to 0.005-0.03 kg m(-3) of additional density in AAIW, and similar to 0-0.02 kg m(-3) in SAMW. We estimate a shallow depth (similar to 300-700 m, above the aragonite saturation horizon) calcium carbonate dissolution rate of 0.4 +/- 0.2 mmol CaCO3 kg(-1) yr(-1), a phosphate remineralization rate of 0.031 +/- 0.009 mu mol P kg(-1) yr(-1), and remineralization ratios of P:N:-O-2:C-org of 1:(15.5 +/- 0.6):(143 +/- 10):(104 +/- 22) for SAMW/AAIW. Our shallow depth calcium carbonate dissolution rate is comparable to previous estimates for our region. Our -O-2:P ratio is smaller than many global averages. Our model suggests neglecting diapycnal mixing of preformed phosphate has likely biased previous estimates of -O-2:P and C-org:P high, but that the C-org:P ratio bias may have been counteracted by a second bias in previous studies from neglecting anthropogenic carbon gradients.

DOI10.1002/2013jc009355
Short TitleJ Geophys Res-Oceans
Integrated Research Themes: 
Student Publication: 
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