Circulation and seasonal evolution of polar waters south of Australia: implications for iron fertilization of the Southern Ocean

Trull, T. W.; Rintoul, Stephen R.; Hadfield, Mark G.; Abraham, Edward R.

doi:10.1016/s0967-0645(01)00003-0

Cited by 138 publications

(132 citation statements)

References 95 publications

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“…To do this, we focused on the higher latitudes regions where the largest seasonal changes in mixing are found (de Boyer Montegut et al, 2004;Trull et al, 2001). Here, we tested whether AOA in either summer or winter was more effective than year-round addition.…”

Section: Importance Of Seasonalitymentioning

confidence: 99%

Assessing carbon dioxide removal through global and regional ocean alkalinization under high and low emission pathways

et al. 2018

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Abstract. Atmospheric carbon dioxide (CO 2 ) levels continue to rise, increasing the risk of severe impacts on the Earth system, and on the ecosystem services that it provides. Artificial ocean alkalinization (AOA) is capable of reducing atmospheric CO 2 concentrations and surface warming and addressing ocean acidification. Here, we simulate global and regional responses to alkalinity (ALK) addition (0.25 PmolALK yr −1 ) over the period 2020-2100 using the CSIRO-Mk3L-COAL Earth System Model, under high (Representative Concentration Pathway 8.5; RCP8.5) and low (RCP2.6) emissions. While regionally there are large changes in alkalinity associated with locations of AOA, globally we see only a very weak dependence on where and when AOA is applied. On a global scale, while we see that under RCP2.6 the carbon uptake associated with AOA is only ∼ 60 % of the total, under RCP8.5 the relative changes in temperature are larger, as are the changes in pH (140 %) and aragonite saturation state (170 %). The simulations reveal AOA is more effective under lower emissions, therefore the higher the emissions the more AOA is required to achieve the same reduction in global warming and ocean acidification. Finally, our simulated AOA for 2020-2100 in the RCP2.6 scenario is capable of offsetting warming and ameliorating ocean acidification increases at the global scale, but with highly variable regional responses.

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Section: Importance Of Seasonalitymentioning

confidence: 99%

Assessing carbon dioxide removal through global and regional ocean alkalinization under high and low emission pathways

et al. 2018

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“…1). Trull et al (2001b) summarised the seasonal evolution of water column properties in the study region. The intense heat loss of surface waters during winter decreases sea surface temperature (SST) to values < 1 • C, resulting in strong vertical convection.…”

Section: Regional Setting and Oceanographymentioning

confidence: 99%

Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

et al. 2018

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Abstract. The Southern Ocean is experiencing rapid and relentless change in its physical and biogeochemical properties. The rate of warming of the Antarctic Circumpolar Current exceeds that of the global ocean, and the enhanced uptake of carbon dioxide is causing basin-wide ocean acidification. Observational data suggest that these changes are influencing the distribution and composition of pelagic plankton communities. Long-term and annual field observations on key environmental variables and organisms are a critical basis for predicting changes in Southern Ocean ecosystems. These observations are particularly needed, since highlatitude systems have been projected to experience the most severe impacts of ocean acidification and invasions of allochthonous species.

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“…* The range in the location of the SAF for the 2011 cruise could be related to a diversification of the PF or SAF into different jets (Sokolov and Rintoul, 2009) but also to crossing the meander of the front twice. Moore and Abbott, 2000;Sambrotto and Mace, 2000;Trull et al, 2001a). Inter-annual variability in O 2 in upper layers of the Southern Ocean have also been related to changes in the entrainment of deeper waters into the mixed layer due to the mixed layer depth variability (Matear et al, 2000;Verdy et al, 2007;Sabine et al, 2008;Sallée et al, 2012).…”

Section: Changes In the Carbon Systemmentioning

confidence: 99%

“…The high latitudes are considered important in terms of POC export, mostly because these areas are dominated by large phytoplankton, in particular diatoms (Buesseler, 1998;Sambrotto and Mace, 2000), and rapid export of carbon to deep waters from phytoplankton blooms is possible (DiTullio et al, 2000;Lourey and Trull, 2001). The POC exported is remineralised to DIC below the mixed layer (Wassman et al, 1990;Asper and Smith Jr., 1999;Trull et al, 2001a;Fripiat et al, 2015). Our results show that the increase in DIC in mode and intermediate waters is fully explained by the uptake of atmospheric CO 2 , which could indicate that there was no detectable change in the rate of export of POC over the 1995-2011 period.…”

Section: Circulation and Biological Processes At Steady Statementioning

confidence: 99%

Carbon uptake and biogeochemical change in the Southern Ocean, south of Tasmania

et al. 2017

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Abstract. Biogeochemical change in the water masses of the Southern Ocean, south of Tasmania, was assessed for the 16-year period between 1995 and 2011 using data from four summer repeats of the WOCE-JGOFS-CLIVAR-GO-SHIP (Key et al., 2015;Olsen et al., 2016) SR03 hydrographic section (at ∼ 140 • E). Changes in temperature, salinity, oxygen, and nutrients were used to disentangle the effect of solubility, biology, circulation and anthropogenic carbon (C ANT ) uptake on the variability of dissolved inorganic carbon (DIC) for eight water mass layers defined by neutral surfaces (γ n ). C ANT was estimated using an improved back-calculation method. Warming (∼ 0.0352 ± 0.0170 • C yr −1 ) of Subtropical Central Water (STCW) and Antarctic Surface Water (AASW) layers decreased their gas solubility, and accordingly DIC concentrations increased less rapidly than expected from equilibration with rising atmospheric CO 2 (∼ 0.86 ± 0.16 µmol kg −1 yr −1 versus ∼ 1 ± 0.12 µmol kg −1 yr −1 ). An increase in apparent oxygen utilisation (AOU) occurred in these layers due to either remineralisation of organic matter or intensification of upwelling. The range of estimates for the increases in C ANT were 0.71 ± 0.08 to 0.93 ± 0.08 µmol kg −1 yr −1 for STCW and 0.35 ± 0.14 to 0.65 ± 0.21 µmol kg −1 yr −1 for AASW, with the lower values in each water mass obtained by assigning all the AOU change to remineralisation. DIC increases in the Sub-Antarctic Mode Water (SAMW, 1.10 ± 0.14 µmol kg −1 yr −1 ) and Antarctic Intermediate Water (AAIW, 0.40 ± 0.15 µmol kg −1 yr −1 ) layers were similar to the calculated C ANT trends. For SAMW, the C ANT increase tracked rising atmospheric CO 2 . As a consequence of the general DIC increase, decreases in total pH (pH T ) and aragonite saturation ( Ar ) were found in most water masses, with the upper ocean and the SAMW layer presenting the largest trends for pH T decrease (∼ −0.0031 ± 0.0004 yr −1 ). DIC increases in deep and bottom layers (∼ 0.24 ± 0.04 µmol kg −1 yr −1 ) resulted from the advection of old deep waters to resupply increased upwelling, as corroborated by increasing silicate (∼ 0.21 ± 0.07 µmol kg −1 yr −1 ), which also reached the upper layers near the Antarctic Divergence (∼ 0.36 ± 0.06 µmol kg −1 yr −1 ) and was accompanied by an increase in salinity. The observed changes in DIC over the 16-year span caused a shoaling (∼ 340 m) of the aragonite saturation depth (ASD, Ar = 1) within Upper Circumpolar Deep Water that followed the upwelling path of this layer. From all our results, we conclude a scenario of increased transport of deep waters into the section and enhanced upwelling at high latitudes for the period between 1995 and 2011 linked to strong westerly winds. Although enhanced upwelling lowered the capacity of the AASW layer to uptake atmospheric CO 2 , it did not limit that of the newly forming SAMW and AAIW, which exhibited C ANT storage rates (∼ 0.41 ± 0.20 mol m −2 yr −1 ) twice that of the upper layers.

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Circulation and seasonal evolution of polar waters south of Australia: implications for iron fertilization of the Southern Ocean

Cited by 138 publications

References 95 publications

Assessing carbon dioxide removal through global and regional ocean alkalinization under high and low emission pathways

Assessing carbon dioxide removal through global and regional ocean alkalinization under high and low emission pathways

Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

Carbon uptake and biogeochemical change in the Southern Ocean, south of Tasmania

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