Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Meridional Ocean Carbon Transport
Stockholm University, Faculty of Science, Department of Meteorology .
Stockholm University, Faculty of Science, Department of Meteorology .
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The ocean's ability to take up and store CO$_{2}$ is a key factor for understanding past and future climate variability. However, qualitative and quantitative understanding of surface-to-interior pathways, and how the ocean circulation affects the CO$_2$ uptake, is limited. Consequently, how changes in ocean circulation may influence carbon uptake and storage and therefore the future climate remains ambiguous.Here we quantify the roles played by ocean circulation and various water masses in the meridional redistribution of carbon.We do so by calculating stream functions defined in Dissolved Inorganic Carbon (DIC) and latitude coordinates, using output from a coupled biogeochemical-physical model. By further separating DIC into components originating from the solubility pump and a residual including the biological pump, air-sea disequilibrium and anthropogenic CO$_2$, we are able to distinguish the dominant pathways of how carbon enters particular water masses.With this new tool, we show that the largest meridional carbon transport occurs in a pole-to-equator transport in the subtropical gyres in the upper ocean. We are able to show that this pole-to-equator DIC transport, and the Atlantic Meridional Overturning Circulation (AMOC) related DIC transport, are mainly driven by the solubility pump. By contrast, the DIC transport associated with deep circulation, including that in Antarctic Bottom Water and Pacific Deep Water, is mostly driven by the biological pump. As these two pumps, as well as ocean circulation, are widely expected to be impacted by anthropogenic changes, these findings have implications for the future role of the ocean as a climate-buffering carbon reservoir.

National Category
Earth and Related Environmental Sciences
Research subject
Atmospheric Sciences and Oceanography
Identifiers
URN: urn:nbn:se:su:diva-172840OAI: oai:DiVA.org:su-172840DiVA, id: diva2:1350170
Available from: 2019-09-10 Created: 2019-09-10 Last updated: 2019-09-11Bibliographically approved
In thesis
1. Atmospheric and oceanic circulation from a thermodynamic perspective
Open this publication in new window or tab >>Atmospheric and oceanic circulation from a thermodynamic perspective
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The climate system is continuously transporting and exchanging heat, freshwater, carbon and other tracers in different spatio-temporal scales. Therefore, analysing the system from a thermodynamic or biogeochemical framework is highly convenient. In this thesis the interaction between the ocean and the atmospheric circulation is analysed using thermodynamical and biogeochemical coordinates. Due to the dimensionality of the climate system stream functions are used to reduce this complexity and facilitate the understanding of the different processes that take place. The first half of this thesis, focuses on the interaction between the atmospheric and the ocean circulation from a thermodynamic perspective. We introduce the hydrothermohaline stream function which combines the atmospheric circulation in humidity-potential temperature (hydrothermal) space and the ocean circulation in salinity-temperature coordinates (thermohaline). A scale factor of 7.1 is proposed to link humidity and salinity coordinates. Future scenarios are showing an increase of humidity in the atmosphere due to the increase of temperatures which results in a widening of the hydrothermal stream function along the humidity coordinate. In a similar way, the ocean circulation in the thermohaline space expands along the salinity coordinate. The link between salinity and humidity changes is strongest at net evaporation regions where the gain of water vapour in the atmosphere results in a salinification in the ocean. In addition, the ocean circulation in latitude-carbon space is investigated. By doing so, we are able to distinguish the roles of different water masses and circulation pathways for ocean carbon. We find that the surface waters in the subtropical gyres are the main drivers of the meridional carbon transport in the ocean. By separating the carbon in its different constituents we show that the carbon transported by the majority of the water masses is a result of the solubility pump. The contribution of the biological pump is predominant in the deep Pacific Ocean. The effects of the Mediterranean Overflow Waters on the North Atlantic are discussed in the final part of the thesis.

Place, publisher, year, edition, pages
Stockholm: Department of Meteorology, Stockholm University, 2019. p. 28
Keywords
Atmospheric circulation, Ocean circulation, Stream functions
National Category
Climate Research Meteorology and Atmospheric Sciences Oceanography, Hydrology and Water Resources
Research subject
Atmospheric Sciences and Oceanography
Identifiers
urn:nbn:se:su:diva-172842 (URN)978-91-7797-827-5 (ISBN)978-91-7797-828-2 (ISBN)
Public defence
2019-10-24, De Geersalen, Svante Arrhenius väg 14, Stockolm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2019-10-01 Created: 2019-09-10 Last updated: 2019-09-23Bibliographically approved
2. Model analysis of ocean carbon storage and transport across climate states
Open this publication in new window or tab >>Model analysis of ocean carbon storage and transport across climate states
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The ocean carbon cycle plays a fundamental role in the Earth’s climate system, on decadal to multi-millennial timescales. Of the carbon held in the ocean, the atmosphere, and the terrestrial biosphere combined, more than 90% resides in the ocean. Carbon enters the surface ocean through air-sea gas exchange and from terrestrial sources. It is transported to the deep ocean with the ocean circulation and through the so-called biological pump, where carbon is taken up in the surface ocean by photosynthetic organisms that fall down and decompose at depth. This thesis contributes to the understanding of the processes involved in ocean carbon storage and transport. It examines how these processes respond to model perturbations, and how this response influences our attempts to simulate glacial-interglacial fluctuations in atmospheric carbon dioxide (CO2).

The thesis investigates the response of the simulated ocean carbon storage, and distribution of the isotopic tracer δ13C, to changes in physical and biological parameters. In the included studies, we use observational as well as proxy records of oceanic properties to evaluate our model simulations. In addition, we use a climate model to interpret proxy evidence of glacial-interglacial changes in ocean δ13C. By using a separation framework, we identify the origin of the carbon in the model ocean, and attribute observed changes to the processes involved.

The results indicate a strong link between ocean carbon storage and the strength of the global ocean overturning circulation. Stronger circulation leads to less carbon storage through a weakening of the biological pump, and through reduced solubility due to an increase in global ocean average temperature.

In simulations of glacial climate, we find that biological adaptability to the surrounding nutrient conditions, through a flexible carbon-to-phosphorus ratio (C/P) in ocean photosynthesis, increases the ocean carbon storage compared to simulations where fixed C/P is applied. The biological flexibility improves the model’s ability to reproduce glacial atmospheric CO2. In line with previous research, we find freshwater input to the North Atlantic to be an important factor for reproducing glacial proxy records. The ensemble of simulations that achieve a good representation of glacial-interglacial δ13C indicates a deglacial whole-ocean change in δ13C of 0.28 ± 0.06‰.

The thesis underlines the importance of the initial state, and the choice of model parameterisations, for the outcome of model ensemble, and intercomparison studies. Finally, it proposes a new method for estimation of ocean carbon transport, and attribution of this transport to different water masses and carbon system processes.

Place, publisher, year, edition, pages
Stockholm: Department of Meteorology, Stockholm University, 2019. p. 42
Keywords
Oceanography, Climate, Climate model, Carbon cycle, Paleoclimate
National Category
Climate Research Oceanography, Hydrology and Water Resources Geosciences, Multidisciplinary
Research subject
Atmospheric Sciences and Oceanography
Identifiers
urn:nbn:se:su:diva-172894 (URN)978-91-7797-829-9 (ISBN)978-91-7797-830-5 (ISBN)
Public defence
2019-10-25, William-Olssonsalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2019-10-02 Created: 2019-09-11 Last updated: 2019-09-24Bibliographically approved

Open Access in DiVA

No full text in DiVA

Search in DiVA

By author/editor
Aldama Campino, AitorÖdalen, MalinDöös, KristoferNycander, Jonas
By organisation
Department of Meteorology
Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 93 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf