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