Subduction of South Pacific waters

Qu, Tangdong; Gao, Shan; Fukumori, Ichiro; Fine, Rana A.; Lindstrom, Eric

doi:10.1029/2007gl032605

Cited by 36 publications

(39 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the MMM, 63 Sv of SAMW and 60 Sv of AAIW is subducted; about half of this subduction occurs in the Pacific Ocean. Qu et al (2008) and Karstensen and Quadfasel (2002a) estimated smaller volumes (;15 Sv) than the MMM (;25 Sv) for similar AAIW density ranges in the Pacific Ocean. We find that, overall, the models used here tend to subduct more fluid than observed.…”

Section: Changes In the Subduction Of Samw And Aaiwmentioning

confidence: 86%

Changes in the Subduction of Southern Ocean Water Masses at the End of the Twenty-First Century in Eight IPCC Models

2010

View full text Add to dashboard Cite

A multimodel comparison method is used to assess the sensitivity of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) formation to climate change. For the Intergovernmental Panel on Climate Change A2 emissions scenario (where atmospheric CO 2 is 860 ppm at 2100), the models show cooling and freshening on density surfaces less than about 27.4 kg m 23 , a pattern that has been observed in the late twentieth century. SAMW (defined by the low potential vorticity layer) and AAIW (defined by the salinity minimum layer) warm and freshen as they shift to lighter density classes. Heat and freshwater fluxes at the ocean surface dominate the projected buoyancy gain at outcrop regions of SAMW and AAIW, whereas the net increase in the Ekman flux of heat and freshwater contributes to a lesser extent. This buoyancy gain, combined with shoaling of the winter mixed layer, reduces the volume of SAMW subducted into the ocean interior by a mean of 8 Sv (12%), and the subduction of AAIW decreases by a mean of 14 Sv (23%; 1 Sv [ 10 6 m 3 s 21 ). Decreases in the projected subduction of the key Southern Ocean upper-water masses imply a slow down in the Southern Ocean circulation in the future, driven by surface warming and freshening. A reduction in the subduction of intermediate waters implies a likely future decrease in the capacity of the Southern Ocean to sequester CO 2 .

show abstract

Section: Changes In the Subduction Of Samw And Aaiwmentioning

confidence: 86%

Changes in the Subduction of Southern Ocean Water Masses at the End of the Twenty-First Century in Eight IPCC Models

2010

View full text Add to dashboard Cite

show abstract

“…A complete analysis on SAMW subduction is given by, for instance, Talley (1999), You (1998), Fine et al (2001Fine et al ( , 2008, Karstensen and Quadfasel (2002a, b), Qu et al (2008), and Sallèe et al (2010).…”

Section: Routementioning

confidence: 99%

Subantarctic mode water: distribution and circulation

Herráiz‐Borreguero

Rintoul

2010

Ocean Dynamics

View full text Add to dashboard Cite

The subduction and export of subantarctic mode water (SAMW) as part of the overturning circulation play an important role in global heat, freshwater, carbon and nutrient budgets. Here, the spatial distribution and export of SAMW is investigated using Argo profiles and a climatology. SAMW is identified by a dynamical tracer: a minimum in potential vorticity. We have found that SAMW consists of several modes with distinct properties in each oceanic basin. This conflicts with the previous view of SAMW as a continuous water mass that gradually cools and freshens to the east. The circulation paths of SAMW were determined using (modified) Montgomery streamlines on the density surfaces corresponding with potential vorticity minima. The distribution of the potential vorticity minima revealed "hotspots" where the different SAMW modes subduct north of the Subantarctic Front. The subducted SAMWs follow narrow export pathways into the subtropical gyres influenced by topography. The export of warmer, saltier modes in these "hotspots" contributes to the circumpolar evolution of mode water properties toward cooler, fresher and denser modes in the east.

show abstract

“…Using observations combined with climatological model runs, Iudicone et al (2007) estimated AAIW transport to be 2.5 Sv through 43°S at intermediate depths (between 400 and 1,500 m depth) in the south Pacific. Qu et al (2008) estimated the Pacific export to be 14.6 Sv within the density range of 26.6 and 27.1 kg.m −3 based on observational data only. The wide range of observational estimates varies with the density range analysed, and the amount of data available, being often based on a limited number of hydrographic sections.…”

Section: Introductionmentioning

confidence: 99%

The origin and fate of mode water in the southern Pacific Ocean

et al. 2011

View full text Add to dashboard Cite

International audienceUnderstanding the origin and fate of mode and intermediate waters (MW) in the subtropical Pacific Ocean is critical for climate, as MW store and export a large volume of CO2, heat, nutrients and salinity to lower latitudes at depths isolated from the atmosphere. A realistic 4D simulation has been used to track and quantify the MW routes and their property characteristics at the last region of subduction. It also allows us to quantify the water transformation after subduction. The simulation has been compared to available observations using a collocation method that interpolated model data onto observations in time and space. The comprehensive comparisons gave us confidence in the model's capacity to reproduce MW characteristics. A quantitative Lagrangian analysis was performed on the model output to depict the origin, the fate and the route of MW circulating in the southern Pacific Ocean, selected in the density range of 26.8-27.4 kg m−3. We found 18 Sv of MW were transported northward in patches through the 42° S section, mostly between 200 and 800 m depth. Of this transport, 8 Sv enters the Pacific Ocean in the upper layer south of Tasmania and subducts in the Pacific. The remainder is not ventilated in the Pacific sector: 4 Sv is advected from the Indian Ocean south of Tasmania at intermediate depth and finally 6 Sv is part of an intermediate depth recirculation within the Pacific Ocean. Particles take up to 30 years to travel northward through our domain before crossing the 42° S section. Southward transport branches also exist: 3 Sv flows southward following the eastern New Zealand coast and then exits through Drake Passage. An additional 4 Sv passes southward in the Tasman Sea, following the eastern Tasmanian coast and enters the Indian Ocean south of Tasmania, as part of the Tasman Leakage. Four different formation sites have been identified, where the MW are last ventilated. These formation sites have different water masses with specific salinity ranges. A study on the evolution of the physical characteristics of each of these water masses has been performed. All MW characteristics become more homogeneous at 42° S than they were when they left the mixed layer. This study confirms the homogenisation of mode waters at intermediate depth in the Pacific Ocean as previously revealed in the Indian Ocean using the same methodology. Transformations are shown to be mostly isopycnal in the Tasman Sea and diapycnal farther east

show abstract

Subduction of South Pacific waters

Cited by 36 publications

References 23 publications

Changes in the Subduction of Southern Ocean Water Masses at the End of the Twenty-First Century in Eight IPCC Models

Changes in the Subduction of Southern Ocean Water Masses at the End of the Twenty-First Century in Eight IPCC Models

Subantarctic mode water: distribution and circulation

The origin and fate of mode water in the southern Pacific Ocean

Contact Info

Product

Resources

About