Winter mesoscale circulation on the shelf slope region of the southern Drake Passage

Zhou, Meng; Zhu, Yiwu; Measures, Christopher I.; Hatta, Mariko; Charette, Matthew A.; Gille, Sarah T.; Frants, Marina; Jiang, Mingshun; Mitchell, B. G.

doi:10.1016/j.dsr2.2013.03.041

Cited by 24 publications

(16 citation statements)

References 53 publications

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“…Regions where deep shelf bathymetry permits intrusions of UCDW are located west of Livingston Island and between King George and Elephant Islands ( Fig. 1A and B; Kang and Lee, 1995;Wilson et al, 1999;Prézelin et al, 2000Prézelin et al, , 2004Zhou et al, 2013). In the late 1970s the deep basins of Bransfield Strait were noted to be locations of intense spawning activity (Makarov et al, 1990).…”

Section: Decadal-scale Variability: the 1998 Ecosystem Shiftmentioning

confidence: 93%

“…For E. superba, the critical (+) SAM, strong northwest winds and (+) SOI and/or (À) Nino3.4 conditions promoting elevated abundance were seasonally extensive, occurring during summer, fall, and spring 21-33 months earlier, suggesting the importance of prolonged winter preconditioning followed by an early (October-December) and intense spring bloom (Marrari et al, 2008). In addition to late-season productivity, northwest winds driving upwelling and cross shelf intrusions of UCDW during fall and winter may control the extent and intensity of subsequent spring blooms in shelf and slope regions (Zhou et al, 2013). These results are in accordance with the fact that the high energetic demands of E. superba reproduction occur over a prolonged period (Ross and Quetin, 1986;Nicol et al, 1995;Quetin and Ross, 2001).…”

Section: Interannual Variability Sam and Windsmentioning

confidence: 94%

See 1 more Smart Citation

Climate variability and spatiotemporal dynamics of five Southern Ocean krill species

Loeb

Santora

2015

Progress in Oceanography

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Section: Decadal-scale Variability: the 1998 Ecosystem Shiftmentioning

confidence: 93%

Section: Interannual Variability Sam and Windsmentioning

confidence: 94%

Climate variability and spatiotemporal dynamics of five Southern Ocean krill species

Loeb

Santora

2015

Progress in Oceanography

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“…The off-shelf transport of iron-rich waters to the bloom region primarily occurs below the mixed layer and involves multiple processes related to the ACC frontal jets (Frants et al, 2013;Measures et al, 2013;Zhou et al, 2013). For example, horizontal advection and entrainment of shelf waters by the SB were both found to influence iron concentrations in southern Drake Passage (Frants et al, 2013;Measures et al, 2013;Zhou et al, 2013). Further downstream in the Weddell-Scotia confluence, cross-frontal eddy activity at the SACCF was shown to transport nutrients that support phytoplankton growth (Kahru et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Physical Drivers of Phytoplankton Bloom Initiation in the Southern Ocean's Scotia Sea

et al. 2019

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The Scotia Sea is the site of one of the largest spring phytoplankton blooms in the Southern Ocean. Past studies suggest that shelf‐iron inputs are responsible for the high productivity in this region, but the physical mechanisms that initiate and sustain the bloom are not well understood. Analysis of profiling float data from 2002 to 2017 shows that the Scotia Sea has an unusually shallow mixed‐layer depth during the transition from winter to spring, allowing the region to support a bloom earlier in the season than elsewhere in the Antarctic Circumpolar Current. We compare these results to the mixed‐layer depth in the 1/6° data‐assimilating Southern Ocean State Estimate and then use the model output to assess the physical balances governing mixed‐layer variability in the region. Results indicate the importance of lateral advection of Weddell Sea surface waters in setting the stratification. A Lagrangian particle release experiment run backward in time suggests that Weddell outflow constitutes 10% of the waters in the upper 200 m of the water column in the bloom region. This dense Weddell water subducts below the surface waters in the Scotia Sea, establishing a sharp subsurface density contrast that cannot be overcome by wintertime convection. Profiling float trajectories are consistent with the formation of Taylor columns over the region's complex bathymetry, which may also contribute to the unique stratification. Furthermore, biogeochemical measurements from 2016 and 2017 bloom events suggest that vertical exchange associated with this Taylor column enhances productivity by delivering nutrients to the euphotic zone.

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“…While numerous artificial (Boyd et al, 2000(Boyd et al, , 2004Gervais et al, 2002;Buesseler et al, 2004Buesseler et al, , 2005de Baar et al, 2005;Hoffmann et al, 2006;Boyd et al, 2012;Smetacek et al, 2012) and natural (Blain et al, 2007;Pollard et al, 2009;Zhou et al, 2010Zhou et al, , 2013 ocean iron-fertilization experiments in the Southern Ocean have demonstrated the role of iron in enhancing the phytoplankton biomass and production in high-nutrient low-chlorophyll (HNLC) regions, determining to what extent fertilization could modify the transfer of particulate organic carbon (POC) to the deep ocean is far from being comprehensively achieved (Lampitt et al, 2008;Morris and Charette, 2013;Le Moigne et al, 2014;Robinson et al, 2014). This is partly due to the short term over which the observations were made, precluding extrapolation to longer timescales.…”

Section: Introductionmentioning

confidence: 99%

Early spring mesopelagic carbon remineralization and transfer efficiency in the naturally iron-fertilized Kerguelen area

et al. 2015

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Abstract. We report on the zonal variability of mesopelagic particulate organic carbon remineralization and deep carbon transfer potential during the Kerguelen Ocean and Plateau compared Study 2 expedition (KEOPS 2; OctoberNovember 2011) in an area of the polar front supporting recurrent massive blooms from natural Fe fertilization. Mesopelagic carbon remineralization (MR) was assessed using the excess, non-lithogenic particulate barium (Ba xs ) inventories in mesopelagic waters and compared with bacterial production (BP), surface primary production (PP) and export production (EP). Results for this early season study are compared with the results obtained during a previous study (2005; KEOPS 1) for the same area at a later stage of the phytoplankton bloom. Our results reveal the patchiness of the seasonal advancement and of the establishment of remineralization processes between the plateau (A3) and polar front sites during KEOPS 2. For the Kerguelen plateau (A3 site) we observe a similar functioning of the mesopelagic ecosystem during both seasons (spring and summer), with low and rather stable remineralization fluxes in the mesopelagic column (150-400 m). The shallow water column (∼ 500 m), the lateral advection, the zooplankton grazing pressure and the pulsed nature of the particulate organic carbon (POC) transfer at A3 seem to drive the extent of MR processes on the plateau. For deeper stations (> 2000 m) located on the margin, inside a polar front meander, as well as in the vicinity of the polar front, east of Kerguelen, remineralization in the upper 400 m in general represents a larger part of surface carbon export. However, when considering the upper 800 m, in some cases, the entire flux of exported carbon is remineralized. In the polar front meander, where successive stations form a time series, two successive events of particle transfer were evidenced by remineralization rates: a first mesopelagic and deep transfer from a past bloom before the cruise, and a second transfer expanding at mesopelagic layers during the cruise. Regarding the deep carbon transfer efficiency, it appeared that above the plateau (A3 site) the mesopelagic remineralization was not a major barrier to the transfer of organic matter to the seafloor (close to 500 m). There, the efficiency of carbon transfer to the bottom waters (> 400 m) as assessed by PP, EP and MR fluxes comparisons reached up to 87 % of the carbon exported from the upper 150 m. In contrast, at the deeper locations, mesopelagic remineralization clearly limited the transfer of carbon to depths of > 400 m. For sites at the margin of the plateau (station E-4W) and the polar front (station F-L), mesopelagic remineralization even exceeded Published by Copernicus Publications on behalf of the European Geosciences Union. S. H. M. Jacquet et al.: Early season mesopelagic carbon remineralizationupper 150 m export, resulting in a zero transfer efficiency to depths > 800 m. In the polar front meander (time series), the capacity of the meander to transfer carbon to depth > 800 ...

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Winter mesoscale circulation on the shelf slope region of the southern Drake Passage

Cited by 24 publications

References 53 publications

Climate variability and spatiotemporal dynamics of five Southern Ocean krill species

Climate variability and spatiotemporal dynamics of five Southern Ocean krill species

Physical Drivers of Phytoplankton Bloom Initiation in the Southern Ocean's Scotia Sea

Early spring mesopelagic carbon remineralization and transfer efficiency in the naturally iron-fertilized Kerguelen area

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