Observing the full ocean volume using Deep Argo floats

Zilberman, Nathalie V.; Thierry, Virginie; King, Brian; Alford, Matthew; André, Xavier; Balem, Kevin; Briggs, Nathan; Chen, Zhaohui; Cabanes, Cécile; Coppola, Laurent; Dall’Olmo, Giorgio; Desbruyères, Damien; Fernandez, Denise; Foppert, Annie; Gardner, Wilford; Gasparin, Florent; Hally, Bryan; Hosoda, Shigeki; Johnson, Gregory C.; Kobayashi, Taiyo; Le Boyer, Arnaud; Llovel, William; Oke, Peter; Purkey, Sarah; Remy, Elisabeth; Roemmich, Dean; Scanderbeg, Megan; Sutton, Philip; Walicka, Kamila; Wallace, Luke; van Wijk, Esmee M.

doi:10.3389/fmars.2023.1287867

Cited by 5 publications

(8 citation statements)

References 107 publications

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“…The comparison with high-quality shipboard observations obtained after each float deployment during the DMB experiment, which have the same accuracy as the gold-standard GO-SHIP measurements (Hood et al, 2010), revealed the calibrated and adjusted salinity measurements from these three floats (rmsd = 0.0007-0.0009 and bias = 9.3 × 10 6 0.0004) are consistent with the Deep Argo target accuracy (±0.002) (Zilberman et al, 2023). However, we observed a step-like noise with an amplitude of 0.001 in the salinity profiles in the deep ocean (>3,000 dbar) when we increased the vertical resolution to 5-dbar.…”

Section: Summary and Discussionsupporting

confidence: 70%

“…While Deep SOLO floats are known to measure temperature and pressure within the target accuracy below 2,000 dbar, the same has yet to be reached for salinity (Roemmich, Sherman, et al, 2019;Zilberman et al, 2023).…”

Section: Salinity Accuracymentioning

confidence: 99%

“…Updated coefficient values for Deep SOLOs have been proposed and used to correct the pressure-dependence compressibility effect (Foppert et al, 2021;Johnson, 2022;Johnson & King, 2023;King et al, 2021;Kobayashi et al, 2021;Murphy & Martini, 2018;Roemmich, Sherman, et al, 2019;Thomas et al, 2020;Walicka et al, 2020Walicka et al, , 2022Zilberman et al, 2019Zilberman et al, , 2020. Currently, the Deep Argo community-recommended coefficient value for Deep SOLO real-time data is 12.5 × 10 8 dbar 1 (Wong et al, 2023).…”

Section: Calibrationmentioning

confidence: 99%

“…For SBE‐61 model, Sea‐Bird applies a default cell compressibility coefficient (CPcor) adjustment of −9.57 × 10 −8 dbar −1 , inherited from the shipboard SBE‐4 model, which uses a different cell encapsulant material (Roemmich, Sherman, et al., 2019; SBE, 2013). This value has been found too large for SBE‐61, and as a result, the default Deep SOLO salinity measurements present a fresh bias when compared with shipboard observations—a bias that increases with increasing depth (Foppert et al., 2021; Kobayashi, 2021; Kobayashi et al., 2021; Roemmich, Sherman, et al., 2019; Zilberman et al., 2019). Examples of these biases in the deep ocean are shown in Figure S1 in Supporting Information (d‐f, blue lines) for our floats.…”

Section: Processingmentioning

confidence: 99%

“…Deep Argo floats are autonomous robotic platforms that measure thermohaline water properties over almost the entire water column in a much higher temporal resolution (days) (Zilberman et al., 2023) when compared with traditional shipboard observations (year‐to‐decades) (Talley et al., 2016). They are a relatively new technology aiming to expand the Argo mission to measure below 2,000 m, but no global Deep Argo array has been implemented yet (Johnson et al., 2015; Johnson & Lyman, 2014; Owens et al., 2022; Roemmich, Alford, et al., 2019; Zilberman et al., 2023). A fleet of about 1,200 deep floats is expected to be operational within 5–10 years and incorporated into the OneArgo design (Owens et al., 2022; Zilberman et al., 2023).…”

Section: Introductionmentioning

confidence: 99%

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Deep Argo Observations of Antarctic Bottom Water in the Deep Fracture Zones of the Southwest Indian Ridge

Menezes,

Robbins,

Furey

et al. 2024

JGR Oceans

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The Madagascar Basin is the primary pathway for Antarctic Bottom Water to ventilate the entire western Indian Ocean as part of the Global Overturning Circulation. The only way for this water mass to reach this basin is by crossing the Southwest Indian Ridge through its deep fracture zones. However, due to the scarcity of observations, the Antarctic Bottom Water presence has only been well‐established in the Atlantis II fracture zone. In May 2023, the Deep Madagascar Basin Experiment deployed three Deep SOLO Argo floats in the exit of the fracture zones that were more likely to transport Antarctic Bottom Water: Atlantis II, Novara, and Melville. These floats have been collecting temperature and salinity profiles every 3–5 days with high vertical resolution in the deep ocean. In the present paper, we use the first 7 months of float data to characterize the Antarctic Bottom Water in the deep fracture zone area, revisiting a half‐century puzzle about the Melville contribution. We also collected shipboard‐based profiles to calibrate float salinity and show it is within the Deep Argo program target accuracy. We find Antarctic Bottom Water in both Melville and Novara fracture zones, not only in Atlantis II. This is the first time the Novara contribution has been revealed. The floats also uncover their distinct properties, which may result from the different mixing histories.

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Section: Summary and Discussionsupporting

confidence: 70%

Section: Salinity Accuracymentioning

confidence: 99%

Section: Calibrationmentioning

confidence: 99%

Section: Processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Deep Argo Observations of Antarctic Bottom Water in the Deep Fracture Zones of the Southwest Indian Ridge

Menezes,

Robbins,

Furey

et al. 2024

JGR Oceans

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Refined Estimates of Global Ocean Deep and Abyssal Decadal Warming Trends

Johnson,

Purkey

2024

Geophysical Research Letters

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Deep and abyssal layer decadal temperature trends from the mid‐1980s to the mid‐2010s are mapped globally using Deep Argo and historical ship‐based Conductivity‐Temperature‐Depth (CTD) instrument data. Abyssal warming trends are widespread, with the strongest warming observed around Antarctic Bottom Water (AABW) formation regions. The warming strength follows deep western boundary currents transporting abyssal waters north and decreases with distance from Antarctica. Abyssal cooling trends are found in the North Atlantic and eastern South Atlantic, regions primarily ventilated by North Atlantic Deep Water (NADW). Deep warming trends are prominent in the Southern Ocean south of about 50°S, the Greenland‐Iceland‐Norwegian (GIN) Seas and the western subpolar North Atlantic, with cooling in the eastern subpolar North Atlantic and the subtropical and tropical western North Atlantic. Globally integrated decadal heat content trends of 21.6 (±6.5) TW in the deep and 12.9 (±1.8) TW in the abyssal layer are more certain than previous estimates.

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The Deep Western Boundary Current of the Southwest Pacific Basin: Insights From Deep Argo

Chandler,

Zilberman,

Sprintall

2024

JGR Oceans

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The deep western boundary current (DWBC) of the Southwest Pacific Basin (SWPB) is the main pathway through which the deep and bottom waters formed around Antarctica are transported northward and distributed throughout the Pacific Ocean. However, historical observations of this current are sparse. Here, we used an unprecedented number of deep‐ocean observations collected by Deep Argo floats since 2016 to examine temperature, salinity, and velocity in the DWBC of the SWPB. Deep Argo trajectory velocities were fastest along the western side of the Kermadec Trench, with an average velocity of m s−1. Trajectories confirmed the existence of a tight recirculation on the eastern side of the Kermadec Trench ( m s−1). This recirculation was likewise seen in an independent eddy‐resolving ocean reanalysis. For the DWBC within the northern Kermadec Trench (26–30°S), Deep Argo profiles and the ocean reanalysis demonstrated seasonal isopycnal heaving of the deep‐ocean that was likely driven by local Ekman pumping and may influence seasonal DWBC transport. At the northern end of the Kermadec Trench, the deep‐ocean salinity maximum was eroded as the DWBC exited the trench to the north through the Louisville Seamount Chain collision zone, thus revealing a previously unidentified region of enhanced deep‐ocean mixing. Although Deep Argo observations accurately estimated vertical turbulent diffusivity in the Samoan Passage (6.1 10−3 to 1.57 10−2 m2 s−1), mixing within the Louisville Seamount Chain collision zone was not due solely to vertical turbulent diffusivity. A global Deep Argo array could reveal wind‐driven seasonal heaving and unexplored deep‐ocean mixing hotspots in other DWBCs.

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Observing the full ocean volume using Deep Argo floats

Cited by 5 publications

References 107 publications

Deep Argo Observations of Antarctic Bottom Water in the Deep Fracture Zones of the Southwest Indian Ridge

Deep Argo Observations of Antarctic Bottom Water in the Deep Fracture Zones of the Southwest Indian Ridge

Refined Estimates of Global Ocean Deep and Abyssal Decadal Warming Trends

The Deep Western Boundary Current of the Southwest Pacific Basin: Insights From Deep Argo

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