scholarly journals Southern Ocean anthropogenic carbon sink constrained by sea surface salinity

2021 ◽  
Vol 7 (18) ◽  
pp. eabd5964
Author(s):  
Jens Terhaar ◽  
Thomas L. Frölicher ◽  
Fortunat Joos
Keyword(s):  
Southern Ocean ◽  
Ocean Circulation ◽  
Carbon Sink ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Anthropogenic Carbon ◽  
Multimodel Ensembles ◽  
Ocean Observations ◽  
Emissions Scenario

The ocean attenuates global warming by taking up about one quarter of global anthropogenic carbon emissions. Around 40% of this carbon sink is located in the Southern Ocean. However, Earth system models struggle to reproduce the Southern Ocean circulation and carbon fluxes. We identify a tight relationship across two multimodel ensembles between present-day sea surface salinity in the subtropical-polar frontal zone and the anthropogenic carbon sink in the Southern Ocean. Observations and model results constrain the cumulative Southern Ocean sink over 1850-2100 to 158 ± 6 petagrams of carbon under the low-emissions scenario Shared Socioeconomic Pathway 1-2.6 (SSP1-2.6) and to 279 ± 14 petagrams of carbon under the high-emissions scenario SSP5-8.5. The constrained anthropogenic carbon sink is 14 to 18% larger and 46 to 54% less uncertain than estimated by the unconstrained estimates. The identified constraint demonstrates the importance of the freshwater cycle for the Southern Ocean circulation and carbon cycle.

Colder and smaller : 10 years of observations of surface salinity by SMOS, Aquarius and SMAP to study mesoscale eddies in the Southern Ocean

2020 ◽  
Author(s):  
Audrey Hasson ◽  
Cori Pegliasco ◽  
Jacqueline Boutin ◽  
Rosemary Morrow
Keyword(s):  
Soil Moisture ◽  
Southern Ocean ◽  
European Space Agency ◽  
Mesoscale Eddy ◽  
Mesoscale Eddies ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Global Ocean ◽  
Surface Salinity ◽  
Sst Anomalies

<p>Since 2010, space missions dedicated to Sea Surface Salinity (SSS) have been providing observations with almost complete coverage of the global ocean and a resolution of about 45 km every 3 days. The European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) mission was the first orbiting radiometer to collect regular SSS observations from space. The Aquarius and SMAP (Soil Moisture Active-Passive) missions of the National Aeronautics and Space Administration (NASA) then reinforced the SSS observing system between mid-2011 and mid-2015 and since mid-2015, respectively.</p><p>Using the most recent SSS Climate Change Initiative project dataset merging data from the 3 missions, this study investigates the SSS signal associated with mesoscale eddies in the Southern Ocean. Eddies location and characteristics are obtained from the daily v3 mesoscale eddy trajectory atlas produced by CLS. SSS anomalies along the eddies journey are computed and compared to Sea Surface Temperature (SST) anomalies (v4 Remote Sensing Systems) as well as the SubAntarctic Front (SAF) position (CTOH, LEGOS). The vertical structure of the eddies is further investigated using profiles from colocated Argo autonomous floats.<span> </span></p><p>This study highlights a robust signal in SSS depending on both the eddies rotation (cyclone/anticyclone) and latitudinal position with respect to the SAF. Moreover, this dependence is not found in SST. These observations reveal oceanic the interaction of eddies with the larger scale ocean water masses. SSS and SST anomalies composites indeed show different patterns either bi-poles linked with horizontal stirring of fronts, mono-poles from trapping water or vertical mixing changes, or a mix of the two.</p><p>This analysis gives strong hints for the erosion of subsurface waters, such as mode waters, induced by enhanced mixing caused by the deep-reaching eddies of the southern ocean.</p>

scholarly journals Sea Surface Salinity Distribution in the Southern Ocean as Observed From Space

2019 ◽  
Vol 124 (5) ◽  
pp. 3186-3205 ◽  
Author(s):  
Cynthia Garcia‐Eidell ◽  
Josefino C. Comiso ◽  
Emmanuel Dinnat ◽  
Ludovic Brucker
Keyword(s):  
Southern Ocean ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Salinity Distribution ◽  
Surface Salinity

scholarly journals Community review of Southern Ocean satellite data needs

2016 ◽  
Vol 29 (2) ◽  
pp. 97-138 ◽  
Author(s):  
A. Pope ◽  
P. Wagner ◽  
R. Johnson ◽  
J.D. Shutler ◽  
J. Baeseman ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Satellite Data ◽  
Marine Biology ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Starting Point ◽  
Data Continuity ◽  
Derived Data

AbstractThis review represents the Southern Ocean community’s satellite data needs for the coming decade. Developed through widespread engagement and incorporating perspectives from a range of stakeholders (both research and operational), it is designed as an important community-driven strategy paper that provides the rationale and information required for future planning and investment. The Southern Ocean is vast but globally connected, and the communities that require satellite-derived data in the region are diverse. This review includes many observable variables, including sea ice properties, sea surface temperature, sea surface height, atmospheric parameters, marine biology (both micro and macro) and related activities, terrestrial cryospheric connections, sea surface salinity, and a discussion of coincident andin situdata collection. Recommendations include commitment to data continuity, increases in particular capabilities (sensor types, spatial, temporal), improvements in dissemination of data/products/uncertainties, and innovation in calibration/validation capabilities. Full recommendations are detailed by variable as well as summarized. This review provides a starting point for scientists to understand more about Southern Ocean processes and their global roles, for funders to understand the desires of the community, for commercial operators to safely conduct their activities in the Southern Ocean, and for space agencies to gain greater impact from Southern Ocean-related acquisitions and missions.

scholarly journals Modeling geologically abrupt climate changes in the Miocene

2010 ◽  
Vol 6 (6) ◽  
pp. 2687-2701
Author(s):  
B. J. Haupt ◽  
D. Seidov
Keyword(s):  
Southern Ocean ◽  
Climate Changes ◽  
Computer Experiments ◽  
Time Span ◽  
Sea Surface ◽  
Central American ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Salinity Changes ◽  
Cooling Trend

Abstract. The gradual cooling of the Cenozoic, including the Miocene epoch, was punctuated by many geologically abrupt warming and cooling episodes – strong deviations from the cooling trend with time span of ten to hundred thousands of years. Our working hypothesis is that some of those warming episodes at least partially might have been caused by dynamics of the emerging Antarctic Ice Sheet, which, in turn, might have caused strong changes of sea surface salinity in the Miocene Southern Ocean. Feasibility of this hypothesis is explored in a series of coupled ocean-atmosphere computer experiments. The results suggest that relatively small and geologically short-lived changes in freshwater balance in the Southern Ocean could have significantly contributed to at least two prominent warming episodes in the Miocene. Importantly, the experiments also suggest that the Southern Ocean was more sensitive to the salinity changes in the Miocene than today, which can attributed to the opening of the Central American Isthmus as a major difference between the Miocene and the present-day ocean-sea geometry.

scholarly journals Comparison of Distributional Statistics of Aquarius and Argo Sea Surface Salinity Measurements

2016 ◽  
Vol 33 (1) ◽  
pp. 103-118 ◽  
Author(s):  
Elizabeth Mannshardt ◽  
Katarina Sucic ◽  
Montserrat Fuentes ◽  
Frederick M. Bingham
Keyword(s):  
Ocean Circulation ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Ocean Basin ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Time And Space ◽  
Surface Salinity ◽  
Statistical Validation ◽  
Earth’S Climate

AbstractSalinity is an indicator of the interaction between ocean circulation and the global water cycle, which in turn affects the regulation of the earth’s climate. To thoroughly understand sea surface salinity’s connection to processes that define the hydrological cycle, such as surface forcing and ocean mixing, there is need for proper validation of remotely sensed salinity products with independent measurements, beyond central tendencies, across the entire distribution of salinity. Because of its fine spatial and temporal coverage, Aquarius presents an ideal measurement system for fully characterizing the distribution and properties of sea surface salinity. Using the first 33 months of Aquarius, version 3.0, level 2 sea surface salinity data, both central tendencies and distributional quantile characteristics across time and space are investigated, and a statistical validation of Aquarius measurements with Argo in situ observations is conducted. Several aspects are considered, including regional characteristics and temporal agreement, as well as seasonal differences by ocean basin and hemisphere. Regional studies examine the time and space scales of variability through time series comparisons and an analysis of quantile properties. Results indicate that there are significant differences between the tails of their respective distributions, especially the lower tail. The Aquarius data show longer, fatter lower tails, indicating higher probability to sample low-salinity events. There is also evidence of differences in measurement variation between Aquarius and Argo. These results are seen across seasons, ocean basins, hemispheres, and regions.

scholarly journals Interrelationships of Sea Surface Salinity, Chlorophyll-α Concentration, and Sea Surface Temperature Near the Antarctic Ice Edge

2021 ◽  
pp. 1-50
Author(s):  
Cynthia Garcia-Eidell ◽  
Josefino C. Comiso ◽  
Max Berkelhammer ◽  
Larry Stock
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Ice Melt ◽  
Biogeochemical Models ◽  
Basin Scale

AbstractSatellite data can now provide a coherent picture of sea surface salinity (SSS), chlorophyll-α concentration (Chl?), sea surface temperature (SST), and sea ice cover across the Southern Ocean. The availability of these data at the basin scale enables novel insight into the physical and biological processes in an area that has historically been difficult to gather in situ data from. The analysis shows large regional and interannual variability of these parameters but also strong coherence across the Southern Ocean. The covariability of the parameters near the marginal ice zone shows a generally negative relationship between SSS and Chl??(r = -0.87). This may in part be attributed to the large seasonality of the variables, but analysis of data within the spring period (from November to December) shows similarly high correlation (r =-0.81). This is the first time that a large-scale robust connection between low salinity and high phytoplankton concentration during ice melt period has been quantified. Chlorophyll-α concentration is also well correlated with SST (r = 0.79) providing a potential indicator of the strength of the temperature limitation on primary productivity in the region. The observed correlation also varied regionally due to differences in ice melt patterns during spring and summer. Overall, this study provides new insights into the physical characteristics of the Southern Ocean as observed from space. In a continually warming and freshening Southern Ocean, the relationships observed here provide key data source for testing ocean biogeochemical models and assessing the effect of sea ice-ocean processes on primary production.

scholarly journals Variability of Sea-Air Carbon Dioxide Flux in Autumn Across the Weddell Gyre and Offshore Dronning Maud Land in the Southern Ocean

2021 ◽  
Vol 7 ◽  
Author(s):  
Margaret Ojone Ogundare ◽  
Agneta Fransson ◽  
Melissa Chierici ◽  
Warren R. Joubert ◽  
Alakendra N. Roychoudhury
Keyword(s):  
Carbon Dioxide ◽  
Southern Ocean ◽  
Carbon Dioxide Flux ◽  
Weddell Sea ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Study Region ◽  
Entire Study ◽  
Weddell Gyre

Sea surface fugacity of carbon dioxide (fCO2ssw) was measured across the Weddell gyre and the eastern sector in the Atlantic Southern Ocean in autumn. During the occupation between February and April 2019, the region of the study transect was a potential ocean CO2 sink. A net CO2 flux (FCO2) of −6.2 (± 8; sink) mmol m–2 d–1 was estimated for the entire study region, with the largest average CO2 sink of −10.0 (± 8) mmol m–2 d–1 in the partly ice-covered Astrid Ridge (AR) region near the coast at 68°S and −6.1 (± 8) mmol m–2d–1 was observed in the Maud Rise (MR) region. A CO2 sink was also observed south of 66°S in the Weddell Sea (WS). To assess the main drivers describing the variability of fCO2ssw, a correlation model using fCO2 and oxygen saturation was considered. Spatial distributions of the fCO2 saturation/O2 saturation correlations, described relative to the surface water properties of the controlling variables (chlorophyll a, apparent oxygen utilization (AOU), sea surface temperature, and sea surface salinity) further constrained the interplay of the processes driving the fCO2ssw distributions. Photosynthetic CO2 drawdown significantly offsets the influence of the upwelling of CO2-rich waters in the central Weddell gyre and enhanced the CO2 sink in the region. FCO2 of −6.9 mmol m–2 d–1 estimated for the Weddell gyre in this study was different from FCO2 of −2.5 mmol m–2 d–1 in autumn estimated in a previous study. Due to low CO2 data coverage during autumn, limited sea-air CO2 flux estimates from direct sea-surface CO2 observations particularly for the Weddell gyre region are available with which to compare the values estimated in this study. This highlights the importance of increasing seasonal CO2 observations especially during autumn/winter to improving the seasonal coverage of flux estimates in the seasonal sea ice-covered regions of the Southern Ocean.

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