High resolution dynamic ocean topography in the Southern Ocean from GOCE

Abstract. Ice core data from Antarctica provide detailed insights into the characteristics of past climate, atmospheric circulation, as well as changes in the aerosol load of the atmosphere. We present high-resolution records of soluble calcium (Ca2+), non-sea-salt soluble calcium (nssCa2+), and particulate mineral dust aerosol from the East Antarctic Plateau at a depth resolution of 1 cm, spanning the past 800 000 years. Despite the fact that all three parameters are largely dust-derived, the ratio of nssCa2+ to particulate dust is dependent on the particulate dust concentration itself. We used principal component analysis to extract the joint climatic signal and produce a common high-resolution record of dust flux. This new record is used to identify Antarctic warming events during the past eight glacial periods. The phasing of dust flux and CO2 changes during glacial-interglacial transitions reveals that iron fertilization of the Southern Ocean during the past nine glacial terminations was not the dominant factor in the deglacial rise of CO2 concentrations. Rapid changes in dust flux during glacial terminations and Antarctic warming events point to a rapid response of the southern westerly wind belt in the region of southern South American dust sources on changing climate conditions. The clear lead of these dust changes on temperature rise suggests that an atmospheric reorganization occurred in the Southern Hemisphere before the Southern Ocean warmed significantly.

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The Challenge of Using Future SWOT Data for Oceanic Field Reconstruction

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-15-0160.1 ◽

2016 ◽

Vol 33 (1) ◽

pp. 119-126 ◽

Cited By ~ 38

Author(s):

Lucile Gaultier ◽

Clément Ubelmann ◽

Lee-Lueng Fu

Keyword(s):

High Resolution ◽

General Circulation ◽

Circulation Model ◽

Ocean General Circulation Model ◽

Two Dimensional ◽

Satellite Mission ◽

The Future ◽

Resolution Model ◽

Mapping Techniques ◽

Ocean Topography

AbstractConventional altimetry measures a one-dimensional profile of sea surface height (SSH) along the satellite track. Two-dimensional SSH can be reconstructed using mapping techniques; however, the spatial resolution is quite coarse even when data from several altimeters are analyzed. A new satellite mission based on radar interferometry is scheduled to be launched in 2020. This mission, called Surface Water and Ocean Topography (SWOT), will measure SSH at high resolution along a wide swath, thus providing two-dimensional images of the ocean surface topography. This new capability will provide a large amount of data even though they are contaminated with instrument noise and geophysical errors. This paper presents a tool that simulates synthetic observations of SSH from the future SWOT mission using SSH from any ocean general circulation model (OGCM). SWOT-like data have been generated from a high-resolution model and analyzed to investigate the sampling and accuracy characteristics of the future SWOT data. This tool will help explore new ideas and methods for optimizing the retrieval of information from future SWOT missions.

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Diatom ooze—A large marine mercury sink

Science ◽

10.1126/science.aat2735 ◽

2018 ◽

Vol 361 (6404) ◽

pp. 797-800 ◽

Cited By ~ 24

Author(s):

Sara Zaferani ◽

Marta Pérez-Rodríguez ◽

Harald Biester

Keyword(s):

High Resolution ◽

Southern Ocean ◽

Marine Sediment ◽

Crucial Role ◽

Anthropogenic Pollution ◽

Atmospheric Mercury ◽

Mercury Accumulation ◽

Accumulation Rates ◽

Sediment Data

The role of algae for sequestration of atmospheric mercury in the ocean is largely unknown owing to a lack of marine sediment data. We used high-resolution cores from marine Antarctica to estimate Holocene global mercury accumulation in biogenic siliceous sediments (diatom ooze). Diatom ooze exhibits the highest mercury accumulation rates ever reported for the marine environment and provides a large sink of anthropogenic mercury, surpassing existing model estimates by as much as a factor of 7. Anthropogenic pollution of the Southern Ocean began ~150 years ago, and up to 20% of anthropogenic mercury emitted to the atmosphere may have been stored in diatom ooze. These findings reveal the crucial role of diatoms as a fast vector for mercury sequestration and diatom ooze as a large marine mercury sink.

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Southern Ocean Deep Circulation and Heat Uptake in a High-Resolution Climate Model

Journal of Climate ◽

10.1175/jcli-d-15-0513.1 ◽

2016 ◽

Vol 29 (7) ◽

pp. 2597-2619 ◽

Cited By ~ 26

Author(s):

Emily R. Newsom ◽

Cecilia M. Bitz ◽

Frank O. Bryan ◽

Ryan Abernathey ◽

Peter R. Gent

Keyword(s):

High Resolution ◽

Southern Ocean ◽

Sea Ice ◽

Climate Model ◽

Water Mass ◽

Global Climate Model ◽

Substantial Reduction ◽

Meridional Overturning Circulation ◽

Heat Uptake ◽

Water Mass Transformation

Abstract The dynamics of the lower cell of the meridional overturning circulation (MOC) in the Southern Ocean are compared in two versions of a global climate model: one with high-resolution (0.1°) ocean and sea ice and the other a lower-resolution (1.0°) counterpart. In the high-resolution version, the lower cell circulation is stronger and extends farther northward into the abyssal ocean. Using the water-mass-transformation framework, it is shown that the differences in the lower cell circulation between resolutions are explained by greater rates of surface water-mass transformation within the higher-resolution Antarctic sea ice pack and by differences in diapycnal-mixing-induced transformation in the abyssal ocean. While both surface and interior transformation processes work in tandem to sustain the lower cell in the control climate, the circulation is far more sensitive to changes in surface transformation in response to atmospheric warming from raising carbon dioxide levels. The substantial reduction in overturning is primarily attributed to reduced surface heat loss. At high resolution, the circulation slows more dramatically, with an anomaly that reaches deeper into the abyssal ocean and alters the distribution of Southern Ocean warming. The resolution dependence of associated heat uptake is particularly pronounced in the abyssal ocean (below 4000 m), where the higher-resolution version of the model warms 4.5 times more than its lower-resolution counterpart.

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A new method for characterising the Antarctic Circumpolar Currents using Argo float temperature and salinity profiles

10.5194/egusphere-egu2020-18595 ◽

2020 ◽

Author(s):

Luke Roberts ◽

Rhiannon Jones ◽

Matthew Donnelly ◽

Katharine Hendry

Keyword(s):

High Resolution ◽

Southern Ocean ◽

Data Processing ◽

Rapid Development ◽

Regional Scale ◽

Global Ocean ◽

Argo Float ◽

Oceanographic Data ◽

The University ◽

The Antarctic

Argo is an array of automated profiling floats, which have allowed the rapid development of high-resolution and high-quality oceanographic data acquisition. The international program has been in operation since the 1990s providing continuous hydrographic data globally. There are now over a million individual float profiles, contributing to our understanding of global ocean physical properties, such as circulation processes at both a local and regional scale. With these innovations come the challenges of data processing, and compilation of user-friendly data products. For example, the Southern Ocean is a critical region that modulates our climate, via heat exchange, carbon storage, biogeochemistry, and primary productivity. An improved quantified understanding of Southern Ocean currents, informed by Argo, must be implemented in policy-relevant high-resolution climate models to advance our understanding of future change.&#160;In May 2019, a new collaboration was formed between the Southern Ocean Argo Resource Centre (British Oceanographic Data Centre) and the University of Bristol. The aims were two-fold: to produce a method for characterising Southern Ocean frontal zones using Argo floats, and to train early career researchers in the University sector in data processing and management. We have created a publicly available code that characterises physical features of the Antarctic Circumpolar Current using Argo float profiles, using minimal software, and without the need to access high-performance computers. The code categorises each profile based on the temperature and salinity &#8216;fingerprints&#8217; of zones between each Southern Ocean front. This allows the user to produce output surface plots from user-specified time-slices and geographic areas, and so compare frontal movement in time and space.

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High-resolution view of the spring bloom initiation and net community production in the Subantarctic Southern Ocean using glider data

ICES Journal of Marine Science ◽

10.1093/icesjms/fsv105 ◽

2015 ◽

Vol 72 (6) ◽

pp. 1999-2020 ◽

Cited By ~ 20

Author(s):

Sandy J. Thomalla ◽

Marie-Fanny Racault ◽

Sebastiaan Swart ◽

Pedro M. S. Monteiro

Keyword(s):

Climate Change ◽

High Resolution ◽

Southern Ocean ◽

High Growth ◽

Biomass Accumulation ◽

Horizontal Resolution ◽

Early Summer ◽

Detection Methods ◽

Net Community Production ◽

Community Production

Abstract In the Southern Ocean, there is increasing evidence that seasonal to subseasonal temporal scales, and meso- to submesoscales play an important role in understanding the sensitivity of ocean primary productivity to climate change. This drives the need for a high-resolution approach to resolving biogeochemical processes. In this study, 5.5 months of continuous, high-resolution (3 h, 2 km horizontal resolution) glider data from spring to summer in the Atlantic Subantarctic Zone is used to investigate: (i) the mechanisms that drive bloom initiation and high growth rates in the region and (ii) the seasonal evolution of water column production and respiration. Bloom initiation dates were analysed in the context of upper ocean boundary layer physics highlighting sensitivities of different bloom detection methods to different environmental processes. Model results show that in early spring (September to mid-November) increased rates of net community production (NCP) are strongly affected by meso- to submesoscale features. In late spring/early summer (late-November to mid-December) seasonal shoaling of the mixed layer drives a more spatially homogenous bloom with maximum rates of NCP and chlorophyll biomass. A comparison of biomass accumulation rates with a study in the North Atlantic highlights the sensitivity of phytoplankton growth to fine-scale dynamics and emphasizes the need to sample the ocean at high resolution to accurately resolve phytoplankton phenology and improve our ability to estimate the sensitivity of the biological carbon pump to climate change.

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