FONDAP funding as a Chilean national center of excellence.
Underway pCO2 and pN2O on US hydrographic surveys. FONDAP funding, to be carried out on the US intensive surveys, assuming they are funded.
Hydrographic study 32S from coast west to 103W, south to 43S, east to coast (late 2003). FONDAP, funded. Click here for cruise schematic
Cimar cruises around 43S (salmon).

Repeat hydrography winter and summer 20S to 45S out to 75W, Juan Fernandez and Easter Island

Howard Freeland, 10 to 40 ARGO floats (Canadian Southern Ocean program and contribution to ARGO). Six floats were deployed in early 2003.

Public access ARGO data (not collaboration with our project of course) include many floats in the SE Pacific.

The ARGO data are publicly available and are online. Check these:
U.S. ARGO site
U.S. ARGO GODAE data server - direct access to data (suggest using GDAC Data Browser)
French ARGO ftp site
Canadian ARGO site - focus on G. Alaska, dig to find SE Pacific
Japanese ARGO site

Andrew Weaver, Richard Karsten modeling interest

Subduction into the southern hemisphere subtropical gyres is dominated volumetrically by Subantarctic Mode Water and the densest of the SAMW's, Antarctic Intermediate Water (AAIW). SAMW refers to the thick mixed layers found directly north of the Subantarctic Front. A map of a proxy of winter time mixed layer depth ( Fig. 1 from Talley, 1999) shows that these layers are thickest in the eastern Indian Ocean and all across the Pacific. The sudden onset of thicker layers in the central Indian Ocean is a mystery to be solved.

In the Pacific Ocean, the densest subducting layer is the densest of the global SAMWs, and is identical there to AAIW. AAIW is formed in the southeastern Pacific, just west of southern Chile, from where it spreads to the entire southern hemisphere and tropics throughout the globe (schematic in Fig. 3, from Talley, 1999). The Pacific AAIW salinity minimum originates from this single source region, through northward subduction. The AAIW found in the Atlantic and Indian originates primarily from this source as well, as a portion of the new AAIW flows eastward through Drake Passage, north of the Subantarctic Front. Some modification of the AAIW takes place during this passage and then it spreads into the South Atlantic's subtropical gyre through eddy shedding and mixing out of the Falkland (Malvinas) loop. (This is not a wind-driven subduction process.) Based on oxygen, potential vorticity and salinity in the Atlantic and Indian Oceans, there is no source of AAIW in these oceans other than the southwestern Atlantic. Hence the primary site to study for AAIW formation is the southeastern Pacific, and the primary sites to study for AAIW spreading are Drake Passage and a subtropical section such as the quarterly XBT line at 30S in the Pacific.

Why are these dense and volumetrically large subducting water masses important for climate? They form a large fraction of the subducted water of the subtropical gyres. They spread northward and cross the subtropical/tropical potential vorticity barrier and are found in a weaker form in the tropics. Variations in Southern Ocean surface properties are therefore communicated throughout the subtropical southern hemisphere and into the tropics through these water masses. In the Atlantic, AAIW is a marked part of the warm layer that moves northward, feeding the North Atlantic thermohaline overturning.

For several decades there have been two separate ideas about SAMW and AAIW formation.

(a) The older concept was that AAIW is formed circumpolarly, through Ekman transport northward across the Subantarctic Front and then sliding northward down isopycnal surfaces.

(b) A more recent concept (still dating to the 1970s, McCartney, 1976) is that SAMW is formed north of the Subantarctic Front through subtropical gyre processes and that AAIW is the densest of the SAMWs, and hence localized in its formation area. (SEISAMW has been recently recognized as a similarly important water mass with respect to its ventilation of the Indian Ocean. )

Both mechanisms are likely active. The northward Ekman transport across the SAF occurs into the local SAMW layer and may be important for creating the great thickness of the SAMW layer. WOCE hydrographic sections show intrusions across the SAF into the SAMW. Eastward transport of the SAMWs then eventually leads to both new SEISAMW, subducting into the Indian Ocean, and new AAIW, partially subducting into the Pacific Ocean and partially passing on to the Atlantic/Indian subtropical gyre. The second source of water for the SAMW and AAIW is subtropical circulation poleward in the western boundary currents, in the traditional model of subtropical subduction.

In the region south of Australia, Rintoul et al (JPO, submitted) have looked at correspondences between Ekman variability, SAMW properties and atmospheric variability and found that Ekman transport across the SAF should not be ignored.

For postscript versions of the plots: Click these with the right mouse button.
Figure 1 postscript (winter mixed layer based on oxygen proxy)
Figure 2 postscript (Indian Ocean PV in SEISAMW)
Figure 3 postscript (intermediate water distributions)

Sources for figures

McCarthy, M. C. and L. D. Talley, 1999. Three-dimensional potential vorticity structure in the Indian Ocean. J. Geophys. Res., 104, 13251-13267.

Talley, L. D., 1999. Some aspects of ocean heat transport by the shallow, intermediate and deep overturning circulations. In Mechanisms of Global Climate Change at Millenial Time Scales, Geophys. Mono. Ser., 112, American Geophysical Union, ed. Clark, Webb and Keigwin, 1-22.