Biofloat observations of a phytoplankton bloom and carbon export in the Drake Passage

Davies, Alexander R.; Véron, Fabrice; Oliver, Matthew J.

doi:10.1016/j.dsr.2019.02.004

Cited by 8 publications

(8 citation statements)

References 72 publications

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“…In December, KE has less of an effect on phytoplankton abundance because as light becomes seasonally available, phytoplankton will utilize the available nutrients, thus leaving a more nutrient (iron) limited environment in January and February (Tagliabue, Aumont, et al, 2014). These potential explanations are in agreement with biofloat observations in the Drake Passage (Davies et al, 2019). A float profiling at high‐frequency (2‐day rather than 10‐day cycle) observed low KE precedes a bloom followed by increasing KE leading to potential dilution within an eddy‐driven subduction event (Davies et al, 2019).…”

Section: Discussionsupporting

confidence: 90%

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Sea Surface Kinetic Energy as a Proxy for Phytoplankton Light Limitation in the Summer Pelagic Southern Ocean

et al. 2020

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The pelagic Southern Ocean is a high‐nutrient, low‐chlorophyll ecosystem. Here, phytoplankton growth is colimited by iron supply and light availability. This creates a general expectation that when light is available in the austral summer (shallow mixing depths), phytoplankton concentrations may be high or low depending on the delivery of iron to the surface layer. When light is not adequate (deep mixing depths), phytoplankton concentrations will likely be low, even if iron is available. Here we show that low surface kinetic energy behaves like a necessary but not sufficient condition for high chlorophyll concentrations. In high kinetic energy conditions, high chlorophyll concentrations are rare. Conversely, under low kinetic energy conditions, both high and low chlorophyll concentrations were observed. We show that higher kinetic energy conditions are related to deeper mixed layers, which is likely a proxy for local light conditions. Probabilistic models of chlorophyll based on surface kinetic energy were able to describe 30% of the spatial variability in monthly chlorophyll climatologies. This means that local light availability, proxied by mixing through kinetic energy, significantly shapes the spatial distribution of chlorophyll in the Southern Ocean. We suggest that regions with consistently higher kinetic energy may not be as sensitive to iron inputs compared to historic iron addition experiments, which were conducted in low surface kinetic energy conditions.

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Section: Discussionsupporting

confidence: 90%

“…These potential explanations are in agreement with biofloat observations in the Drake Passage (Davies et al, 2019). A float profiling at high‐frequency (2‐day rather than 10‐day cycle) observed low KE precedes a bloom followed by increasing KE leading to potential dilution within an eddy‐driven subduction event (Davies et al, 2019).…”

Section: Discussionsupporting

confidence: 90%

Sea Surface Kinetic Energy as a Proxy for Phytoplankton Light Limitation in the Summer Pelagic Southern Ocean

et al. 2020

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“…S13), indicating that the MLP is the dominant carbon export pathway during the pre-bloom period when strong variability in the mixing layer depth occurs. Evaluating the total annual export from the ESP is more challenging due to the difficulty to integrate fluxes from episodic and local ESP events 23 . Our method also does not estimate net ESP export as upward fluxes are not considered 16 .…”

Section: Implications For Oceanic Carbon Storagementioning

confidence: 99%

“…To determine the relative importance of each of these pathways for carbon sequestration, it is essential to study these mechanisms in the context of the seasonality in characteristics of the upper ocean particle assemblage 4 . Although previous studies 11,[21][22][23] revealed that both the PIPs and BGP vary seasonally, concomitant and extensive in situ observations of these pathways, including upper ocean particle characteristics, are extremely rare. Therefore, little is known about their relative importance over complete annual cycles.…”

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confidence: 99%

Seasonality of downward carbon export in the Pacific Southern Ocean revealed by multi-year robotic observations

et al. 2023

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At high latitudes, the biological carbon pump, which exports organic matter from the surface ocean to the interior, has been attributed to the gravitational sinking of particulate organic carbon. Conspicuous deficits in ocean carbon budgets challenge this as a sole particle export pathway. Recent model estimates revealed that particle injection pumps have a comparable downward flux of particulate organic carbon to the biological gravitational pump, but with different seasonality. To date, logistical constraints have prevented concomitant and extensive observations of these mechanisms. Here, using year-round robotic observations and recent advances in bio-optical signal analysis, we concurrently investigated the functioning of two particle injection pumps, the mixed layer and eddy subduction pumps, and the gravitational pump in Southern Ocean waters. By comparing three annual cycles in contrasting physical and biogeochemical environments, we show how physical forcing, phytoplankton phenology and particle characteristics influence the magnitude and seasonality of these export pathways, with implications for carbon sequestration efficiency over the annual cycle.

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“…Based on the scale factors provided by the manufacturer, the chlorophyll and CDOM concentration can be derived. Then the spikes are removed, a 5-m bin-averaged smoothing is used in the data quality control of the chlorophyll and CDOM concentration and a three-bin vertical running mean is performed to reduce the noise signal (Davies et al 2019). To remove the high-frequency signals and noises, a 50-km horizontal filtering (Shu et al 2016) is carried out to smooth the data in horizontal plane.…”

Section: A Glider Datasetmentioning

confidence: 99%

Constructing the Three-Dimensional Structure of an Anticyclonic Eddy in the South China Sea Using Multiple Underwater Gliders

Wang

Zhang

et al. 2019

Journal of Atmospheric and Oceanic Technology

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Mesoscale eddies have great influence on heat and material transport in the ocean and thus play an important role in modulating the global climate variability. However, our understanding of their fine three-dimensional (3D) thermohaline and biogeochemical structure remains incomplete because of the scarcity of high-resolution measurements. This research aims to construct the fine 3D structure of an anticyclonic eddy in the northern South China Sea (NSCS) to validate the effectiveness of a glider network for observing mesoscale eddies. Twelve Petrel gliders were deployed in NSCS during August 2017 to gather fine information of an anticyclonic eddy. By combining the high-resolution in situ glider data and the sea level anomaly data, we have constructed a detailed 3D structure of the eddy. The analysis results of the absolute dynamic topography map and the water mass comparison imply that the anticyclonic eddy may generate from eddy shedding of the Kuroshio loop current. The maximum potential temperature anomaly (over 3°C) appears at the thermocline, and the maximum salinity anomaly (~0.8 psu) exists at ~50 m. The maximum value of the dissolved oxygen concentration (~7.5 mg L−1) appears at 50–80 m. The maximum chlorophyll concentration (~1.2 μg L−1) lies at 80–120 m, just below that of the dissolved oxygen concentration. The colored dissolved organic matter concentration increases with depth, with the mean value being less than 1.23 ppb above 50 m and beyond 2.2 ppb at 500–800 m. The results verify the capability of the glider network to observe a fine-scaled 3D structure of mesoscale eddies and will provide a useful guide for future eddy observations.

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Biofloat observations of a phytoplankton bloom and carbon export in the Drake Passage

Cited by 8 publications

References 72 publications

Sea Surface Kinetic Energy as a Proxy for Phytoplankton Light Limitation in the Summer Pelagic Southern Ocean

Sea Surface Kinetic Energy as a Proxy for Phytoplankton Light Limitation in the Summer Pelagic Southern Ocean

Seasonality of downward carbon export in the Pacific Southern Ocean revealed by multi-year robotic observations

Constructing the Three-Dimensional Structure of an Anticyclonic Eddy in the South China Sea Using Multiple Underwater Gliders

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