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The role of Southern Ocean stratification in future ocean CO2 and heat uptake

Applicant Haumann Alexander
Number 175162
Funding scheme Early Postdoc.Mobility
Research institution Atmospheric and Oceanic Sciences Princeton University
Institution of higher education Institution abroad - IACH
Main discipline Oceanography
Start/End 01.10.2017 - 31.03.2019
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All Disciplines (4)

Discipline
Oceanography
Climatology. Atmospherical Chemistry, Aeronomy
Hydrology, Limnology, Glaciology
Meteorology

Keywords (11)

Freshwater; Climate change; Heat; Ocean; Future; Southern Ocean; Stratification; Sea ice; Carbon-dioxide; Global climate model; CO2

Lay Summary (German)

Lead
Der Austausch von Wassermassen zwischen dem oberflächennahen und tiefen Ozean hat einen grossen Einfluss auf das Klima der Erde, da durch diesen Prozess auch grosse Mengen des klimawirksamen Treibhausgases Kohlenstoffdioxid und Wärme zwischen dem Ozean und der Atmosphäre ausgetauscht werden. Dieser Austausch findet vorwiegend im Südpolarmeer statt, wo tiefes Wasser an die Oberfläche gelangt und wieder absinkt. Bei diesem Prozess spielt die vertikale Dichteschichtung der Wassersäule eine wesentliche Rolle und mögliche zukünftige Veränderungen dieser Dichteschichtung könnten zu einer Verstärkung oder Abschwächung der globalen Klimaerwärmung führen. Bis heute haben Klimamodelle jedoch Schwierigkeiten diese Dichteschichtung im Südpolarmeer realistisch abzubilden, was zu Unsicherheiten in Abschätzungen des zukünftigen Klimawandels führt.
Lay summary

Inhalt und Ziel des Forschungsprojekts

Das Ziel unseres Projektes ist es den Einfluss von Veränderungen der Dichteschichtung im Südpolarmeer auf die zukünftige Aufnahme von Kohlenstoffdioxid und Wärme besser zu verstehen und dadurch Unsicherheiten in Modellabschätzungen der zukünftigen globalen Klimaerwärmung einzuschränken. Dafür verwenden wir neue Messdaten und Analysemethoden um einerseits bestehende Modellsimulationen zu evaluieren und um andererseits die Dichteschichtung in Modellsimulationen des Südpolarmeers zu verbessern.

 

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Unser Projekt wird neue Erkenntnisse über den Einfluss von Veränderungen im Südpolarmeer auf die zukünftige Klimaerwärmung liefern und helfen diese Prozesse in Klimamodellen zu verbessern. Unsere Arbeit zielt darauf ab die bestehenden Unsicherheiten in den zulässigen Kohlenstoffdioxidemissionen und dem Meerespiegelanstieg, welche mit dem politischen 1.5°C Ziel verbunden sind, zu verringern und somit eine bessere Planung von Anpassungsstrategien an den Klimawandel zu ermöglichen.

Direct link to Lay Summary Last update: 28.06.2017

Responsible applicant and co-applicants

Publications

Publication
Supercooled Southern Ocean Waters
Haumann F. Alexander, Moorman Ruth, Riser Stephen C., Smedsrud Lars H., Maksym Ted, Wong Annie P. S., Wilson Earle A., Drucker Robert, Talley Lynne D., Johnson Kenneth S., Key Robert M., Sarmiento Jorge L. (2020), Supercooled Southern Ocean Waters, in Geophysical Research Letters, 47(20), e2020GL090.
Twenty first century changes in Antarctic and Southern Ocean surface climate in CMIP6
Bracegirdle Thomas J., Krinner Gerhard, Tonelli Marcos, Haumann F. Alexander, Naughten Kaitlin A., Rackow Thomas, Roach Lettie A., Wainer Ilana (2020), Twenty first century changes in Antarctic and Southern Ocean surface climate in CMIP6, in Atmospheric Science Letters, 21(9), e984.
Sea‐Ice Induced Southern Ocean Subsurface Warming and Surface Cooling in a Warming Climate
Haumann F. Alexander, Gruber Nicolas, Münnich Matthias (2020), Sea‐Ice Induced Southern Ocean Subsurface Warming and Surface Cooling in a Warming Climate, in AGU Advances, 1(2), e2019AV000.
The residence time of Southern Ocean surface waters and the 100,000-year ice age cycle
Hasenfratz Adam P., Jaccard Samuel L., Martínez-García Alfredo, Sigman Daniel M., Hodell David A., Vance Derek, Bernasconi Stefano M., Kleiven Helga (Kikki) F., Haumann F. Alexander, Haug Gerald H. (2019), The residence time of Southern Ocean surface waters and the 100,000-year ice age cycle, in Science, 363(6431), 1080-1084.
Atmospheric influences on the anomalous 2016 Antarctic sea ice decay
Schlosser Elisabeth, Haumann F. Alexander, Raphael Marilyn N. (2018), Atmospheric influences on the anomalous 2016 Antarctic sea ice decay, in The Cryosphere, 12(3), 1103-1119.

Datasets

Seawater stable isotope sample measurements from the Antarctic Circumnavigation Expedition (ACE)

Author Haumann, F. Alexander; Leonard, Katherine; Meredith, Michael P.; Arrowsmith, Carol; Gorodetskaya, Irina V.; Hutchings, Jennifer; Lehning, Michael; Leng, Melanie J.; Stammerjohn, Sharon; Tsukernik, Maria; Weber, Yvonne
Publication date 19.02.2019
Persistent Identifier (PID) 10.5281/zenodo.1494915
Repository Zenodo


ODP 1094 downcore data from the publication "The residence time of Southern Ocean surface waters and the 100,000-year ice age cycle"

Author Hasenfratz, Adam; Jaccard, Samuel; Martinez-Garcia, Alfredo; Sigman, Daniel M.; Hodell, David A.; Vance, D.; Bernasconi, Stefano M.; Kleiven, Helga (Kikki) F.; Haumann, F. Alexander; Haug, Gerald H.
Publication date 08.03.2019
Persistent Identifier (PID) 10.7892/boris.127004
Repository Bern Open Repository and Information System


Sea-ice induced Southern Ocean subsurface warming and surface cooling in a warming climate: ROMS model data

Author Haumann, F. Alexander; Gruber, Nicolas; Münnich, Matthias
Publication date 31.03.2020
Persistent Identifier (PID) 10.5281/zenodo.3709154
Repository Zenodo
Abstract
This data set contains model output data from the regional ocean modelling system (ROMS) that was set up for the Southern Ocean (south of 24 °S; Haumann, 2016) to analyze the effects of changing surface freshwater and momentum fluxes on Southern Ocean water-mass changes over the period 1980 to 2011. All data is provided in NetCDF format. The data set contains 3 sets 40-year long model spin-up, control, and 3 perturbation simulations each. The sets differ by their model mean state to assess the effect of surface salinity biases on the results. One set of simulations are reference simulations where salinity is restored to the observed surface salinity during model spin-up, and the other two sets are simulations in which the restoring surface salinity has been altered by plus and minus 0.1 PSU, respectively. The control and perturbation simulations are 40-year extensions of the respective model spin-up simulations. In the perturbation simulations either the surface freshwater fluxes or momentum fluxes are instantaneously perturbed after the spin-up simulation to reflect the observation-derived changes in these surface fluxes and then held constant (at the perturbed level) for 40 years. They consist of sea-ice freshwater flux, glacial meltwater flux, and atmosphere-ocean momentum flux changes. Details on the model setup, forcing, and simulations can be obtained from the related research article by Haumann et al. (2020; https://doi.org/10.1029/2019AV000132).

Physical and biogeochemical oceanography data from underway measurements with an AquaLine Ferrybox during the Antarctic Circumnavigation Expedition (ACE)

Author Haumann, F. Alexander; Robinson, Charlotte; Thomas, Jenny; Hutchings, Jennifer; Pina Estany, Carles; Tarasenko, Anastasia; Gerber, Franziska; Leonard, Katherine
Publication date 31.03.2020
Persistent Identifier (PID) 10.5281/zenodo.3660852
Repository Zenodo
Abstract
This data set contains measurements from various sensors installed on the Aqualine Ferrybox system that was connected to the underway seawater supply in the Southern Ocean during the Antarctic Circumnavigation Expedition (ACE). Data was collected continuously except for periods when the pump of the underway system was switched off or the system was turned off. Data collection covers all three cruise legs in the period 24th December 2016 to 18th March 2017. Data collected with the CTG MiniPack CTD-F are temperature, salinity, pressure, and turbidity. Data collected by the Aanderaa oxygen optode include dissolved oxygen and oxygen saturation. An SBE 18 sensor measured pH. The CTG UniLux fluorometer measured chlorophyll-a concentration. All data has been quality controlled and post-cruise calibrated. Data is provided at 1-minute intervals along the cruise track. In addition, we provide satellite data (sea-surface temperature, sea-surface height, geostrophic velocity, sea-ice concentration) that was interpolated to the cruise-track and an estimate of frontal positions to supplement this underway data set where data was missing or for additional information. This circumpolar data set provides insights into the circumpolar surface ocean conditions and biogeochemistry of the Southern Ocean during one austral summer season.Note on version 1.0: The first version of this data set only contains temperature, salinity, pressure, and potential density in the post-processed file, since post-processing and quality control for turbidity, chlorophyll-a, dissolved oxygen, oxygen saturation, and pH have not been finalized. These variables will be added to the post-processed data file in a future release.

Physical and biogeochemical oceanography data from Conductivity, Temperature, Depth (CTD) rosette deployments during the Antarctic Circumnavigation Expedition (ACE)

Author Henry, Tahlia; Robinson, Charlotte; Haumann, F. Alexander; Thomas, Jenny; Hutchings, Jennifer; Schuback, Nina; Tsukernik, Maria; Leonard, Katherine
Publication date 17.09.2019
Persistent Identifier (PID) 10.5281/zenodo.3247384
Repository Zenodo
Abstract
This data set contains measurements from various sensors mounted on the Conductivity, Temperature, Depth (CTD) rosette that was deployed in the Southern Ocean during the Antarctic Circumnavigation Expedition (ACE). 63 CTD casts were carried out during three legs in the period 21st December 2016 to 16th March 2017, including one test cast and one failed cast, for which no data is available. Data include temperature, salinity, pressure, dissolved oxygen, oxygen saturation, chlorophyll-a concentration, backscatter, and photosynthetically active radiation (PAR) and reported are also the computed variables density, depth, and sound velocity. All data has been quality controlled and post-cruise calibrated, except for the oxygen data. Data is provided at 1 dbar pressure intervals for the up- and down-casts separately and as a merged bottle file when Niskin bottles were closed. This circumpolar data set provides insights into the circumpolar hydrography and biogeochemistry of the Southern Ocean during one austral summer season.

Seawater salinity sample measurements from the Antarctic Circumnavigation Expedition (ACE)

Author Haumann, F. Alexander; Leonard, Katherine; Budéus, Gereon; Meredith, Michael P.; Gorodetskaya, Irina V.; Hutchings, Jennifer; Stammerjohn, Sharon; Tsukernik, Maria; Thomas, Jenny
Publication date 19.10.2020
Persistent Identifier (PID) 10.5281/zenodo.1494924
Repository Zenodo
Abstract
This data set contains salinity measurements from discrete seawater samples that were collected in the Southern Ocean (south of 30deg S) during the Antarctic Circumnavigation Expedition (ACE). 657 samples were collected during the period December 24th, 2016 and March 18th, 2017 in the Southern Ocean from the surface ocean using the ship's underway line (UW; 328 samples) and in vertical profiles using Niskin bottles mounted on the CTD rosette (273 samples). A few additional samples (56) were collected from a parallel cast with a trace-metal rosette, with a bucket, and as duplicates to ensure data quality. All samples were analyzed for their salinity and results are reported on the Practical Salinity Scale 1978 (PSS-78; Sea-Bird Electronics, Inc., 1989). Measurements were performed on a Guildline Autosal Laboratory Salinometer 8400(B) at CSIRO (Hobart, Australia) for samples collected during leg 1, and on a OPTIMARE Precision Salinometer (OPS) at the Alfred Wegener Institute (Bremerhaven, Germany) for samples collected during legs 2 and 3. This circumpolar data set provides insights into the hydrological cycle of the Southern Ocean and the processes (precipitation, evaporation, sea-ice melting and freezing, ice-berg and land-ice melting) that determine the salinity of a certain water mass. It is being used to calibrate the CTD sensor vertical profiles (Henry et al., 2020) and thermosalinograph sensor underway measurements (Haumann et al., 2020) from the ACE cruise.

Seawater temperature profiles from Expendable Bathythermograph (XBT) probe deployments during the Antarctic Circumnavigation Expedition (ACE)

Author Haumann, F. Alexander; Thomas, Jenny; Tsukernik, Maria; Leonard, Katherine
Publication date 20.10.2020
Persistent Identifier (PID) 10.5281/zenodo.3836648
Repository Zenodo
Abstract
This data set contains vertical seawater temperature profiles measured by Expendable Bathythermograph (XBT) probes that were deployed in the Southern Ocean during the Antarctic Circumnavigation Expedition (ACE) on board the R/V Akademik Tryoshnikov. 40 XBT probes were deployed during legs 2 and 3 of the expedition in the period 25th January, 2017 to 17th March, 2017. The XBT probes are manufactured and distributed by T.S.K./Sippican Tsurumi-Seiki Co. Ltd., Yokohama, Japan (http://www.tsk-jp.com) and are of the type T-07, which is rated at a ship speed of up to 15 knots. These probes have a measuring time of 123 seconds and maximum measurement depth of about 789 m. Probes were launched from a handheld device from the stern of the ship either on the port or starboard side while the ship was moving. The deck unit recorded the temperature and the time since the probe was launched. This time was then converted to depth using the known fall rate of the probe in seawater and the coefficients provided by the manufacturer (WMO standards; Hanawa et al., 1995). The profiles were corrected for known surface biases (Kizu and Hanawa, 2002; Uehara et al., 2008). We provide the raw data, the data produced by using the coefficients provided by the manufacturer, and a corrected version in which we apply an empirical correction based on a comparison with CTD data (Henry et al., 2019), where XBT profiles were launched alongside the CTD deployment. The data has been quality controlled by comparing it to a number of CTD profiles. Data is provided at full vertical resolution and a 1-m averaged resolution. In addition, we provide derived variables such as surface mixed layer depth (temperature threshold) estimates. We are grateful to the crew of the R/V Akademik Tryoshnikov and AARI for donating these probes to our project. Their use-by date had expired, however this was not seen as an issue. This data set provides insights into the hydrography of the Southern Ocean during one austral summer season and complements the CTD temperature profiles measured during ACE by filling in the gaps between CTD stations.

Collaboration

Group / person Country
Types of collaboration
Jean-Baptiste Sallée, LOCEAN-IPSL, Sorbonnes Université France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Gereon Budéus, Alfred Wegener Institute Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Charlotte Robinson, Remote Sensing and Satellite Research Group, Curtin University Australia (Oceania)
- in-depth/constructive exchanges on approaches, methods or results
Irina Gorodetskaya, CESAM, University of Aveiro Portugal (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Katherine Leonard, Laboratoire des sciences cryosphériques EPFL - ENAC - IIE - CRYOS, EPFL Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Daniel Sigman, Department of Geosciences, Princetion University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Marilyn Raphael, Department of Geography, University of California United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Ivana Cerovecki, Scripps Institution of Oceanography, UC San Diego United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Jennifer Hutchings, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Melanie Leng, British Geological Survey Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Julia Schmale, Paul Scherrer Institute Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Elisabeth Schlosser, Institute of Atmospheric and Cryospheric Sciences, University of Innsbruck Austria (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dirk Notz, Max Planck Institute for Meteorology Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Carolina Dufour, McGill University Canada (North America)
- in-depth/constructive exchanges on approaches, methods or results
Stanley Jacobs, Columbia University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
Rafael Catany, ARGANS Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Samuel Jaccard, Institute of Geological Sciences, University of Bern Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Michael Meredith, British Antarctic Survey Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Jorge Sarmiento, Atmospheric and Oceanic Sciences Program, Princeton University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Michael Winton, Geophysical Fluid Dynamics Laboratory United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
Paul Holland, British Antarctic Survey Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Estrella Olmedo, Barcelona Expert Centre, Institut de Ciències del Mar, Barcelona Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Alessandro Silvano, Institute for Marine and Antarctic Studies, University of Tasmania Australia (Oceania)
- in-depth/constructive exchanges on approaches, methods or results
Stephen Griffies, Geophysical Fluid Dynamics Laboratory United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
EGU General Assembly 2019 Talk given at a conference Quantifying the contribution of the Atlantic sector of the SourthernOcean to the lower limb of the global circulation 12.04.2019 Vienna, Austria Haumann Alexander;
EGU General Assembly 2019 Talk given at a conference Improved satellite sea surface salinity maps to further the understanding of the Southern Ocean dynamics 10.04.2019 Vienna, Austria Haumann Alexander;
AGU Fall Meeting 2018 Talk given at a conference A Previously Unrecorded Anomaly in the Southern Ocean Climate System 12.12.2018 Washington D.C., United States of America Haumann Alexander;
AGU Fall Meeting 2018 Poster Antarctic Ocean surface residence time and the development of the hundred-thousand-year ice age cycle 11.12.2018 Washington D.C., United States of America Haumann Alexander;
McGill Departemental Seminars Individual talk Sea-ice induced Southern Ocean surface cooling in a warming climate 03.12.2018 Montreal, Canada Haumann Alexander;
ESA Ocean Salinity Science Conference Talk given at a conference Southern Ocean freshwater sources inferred from oxygen isotope data 09.11.2018 Paris, France Haumann Alexander;
ORCHESTRA and RoSES Annual Science Meeting 2018 Talk given at a conference Southern Ocean sourced separation of global surface and bottom waters inferred from oxygen isotope data 04.07.2018 Southampton, Great Britain and Northern Ireland Haumann Alexander;
ISSI Team meeting on Satellite-derived estimates of Antarctic snow- and ice-thickness Talk given at a conference Sea-Ice Induced Changes in Southern Ocean Hydrography and the role of sea-ice drift and thickness 26.06.2018 Bern, Switzerland Haumann Alexander;
Polar2018 Talk given at a conference Sources of Southern Ocean Freshening Inferred from Oxygen Isotope Data 19.06.2018 Davos, Switzerland Haumann Alexander;
SOCCOM Annual Meeting 2018 Talk given at a conference Importance of Southern Ocean marginal sea-ice zone for ocean carbon- dioxide and heat release 11.06.2018 Princeton, United States of America Haumann Alexander;
EGU General Assembly 2018 Poster Importance of sea-ice processes for Southern Ocean stratification inferred from the oxygen isotopic composition of seawater 11.04.2018 Vienna, Austria Haumann Alexander;
2018 Ocean Sciences Meeting Talk given at a conference Sea-Ice Induced Changes in Southern Ocean Hydrography and their Representation in Global Climate Models 16.02.2018 Portland, OR, United States of America Haumann Alexander;
2018 Ocean Sciences Meeting Poster Constraining the balance of Southern Ocean surface freshwater fluxes using oxygen isotope data 13.02.2018 Portland, OR, United States of America Haumann Alexander;


Self-organised

Title Date Place

Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
2018 CMI Annual Meeting Talk 25.04.2018 London, Great Britain and Northern Ireland Haumann Alexander;


Awards

Title Year
BAS Honorary Researcher 2019

Associated projects

Number Title Start Funding scheme
186681 The role of Southern Ocean stratification in future ocean CO2 and heat uptake 01.07.2019 Postdoc.Mobility

Abstract

The upwelling and subduction of water masses in the Southern Ocean plays a vital role in the global climate system, because they redistribute carbon and heat between the atmosphere and the deep ocean. Human-induced future changes in the marginally stable vertical density gradient (here referred to as stratification) of this region could critically alter this vertical exchange and therefore the uptake and release of carbon-dioxide (CO2) and heat by the ocean. Therefore, such changes could considerably diminish or amplify global warming. Yet, current global climate models reveal large biases in this region leading to large uncertainties in future climate projections. In this project, we investigate the effect of stratification changes on the future CO2 and heat uptake by the Southern Ocean and constrain the related uncertainty in projected future global climate change. For this purpose, we hypothesize that the simulated surface freshwater flux balance is a key driver of the Southern Ocean stratification in global climate models and determines their sensitivity of the future uptake of CO2 and heat to climatic changes. We will approach this challenge in two ways: On the one hand, we will use new observational constraints in surface freshwater, heat, and CO2 fluxes to evaluate the existing future projections. This analysis will provide insights into the process responsible for the large discrepancies between models and help to constrain uncertainties. On the other hand, we will tweak an existing global climate model to provide a more realistic Southern Ocean circulation by adjusting the surface freshwater fluxes using observational estimates. We will then impose freshwater flux scenarios by perturbing the surface fluxes according to expected future changes to study the response of CO2 and heat uptake to changes in the surface freshwater fluxes. This latter analysis might also reveal potential surprises in the effect of Southern Ocean stratification changes on global warming that might not be represented in current global climate models due to their biases.
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