Capturing optically important constituents and properties in a marine biogeochemical and ecosystem model
We present a numerical model of the ocean that couples a three-stream radiative transfer component with a marine biogeochemical–ecosystem component in a dynamic three-dimensional physical framework. The radiative transfer component resolves the penetration of spectral irradiance as it is absorbed an...
| Main Authors: | , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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Copernicus GmbH
2015
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| Online Access: | http://hdl.handle.net/1721.1/98105 https://orcid.org/0000-0002-3102-0341 |
| _version_ | 1811075699137576960 |
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| author | Hickman, A. E. Gregg, W. W. Mouw, C. B. Dutkiewicz, Stephanie Jahn, Oliver Follows, Michael J |
| author2 | Massachusetts Institute of Technology. Center for Global Change Science |
| author_facet | Massachusetts Institute of Technology. Center for Global Change Science Hickman, A. E. Gregg, W. W. Mouw, C. B. Dutkiewicz, Stephanie Jahn, Oliver Follows, Michael J |
| author_sort | Hickman, A. E. |
| collection | MIT |
| description | We present a numerical model of the ocean that couples a three-stream radiative transfer component with a marine biogeochemical–ecosystem component in a dynamic three-dimensional physical framework. The radiative transfer component resolves the penetration of spectral irradiance as it is absorbed and scattered within the water column. We explicitly include the effect of several optically important water constituents (different phytoplankton functional types; detrital particles; and coloured dissolved organic matter, CDOM). The model is evaluated against in situ-observed and satellite-derived products. In particular we compare to concurrently measured biogeochemical, ecosystem, and optical data along a meridional transect of the Atlantic Ocean. The simulation captures the patterns and magnitudes of these data, and estimates surface upwelling irradiance analogous to that observed by ocean colour satellite instruments. We find that incorporating the different optically important constituents explicitly and including spectral irradiance was crucial to capture the variability in the depth of the subsurface chlorophyll a (Chl a) maximum. We conduct a series of sensitivity experiments to demonstrate, globally, the relative importance of each of the water constituents, as well as the crucial feedbacks between the light field, the relative fitness of phytoplankton types, and the biogeochemistry of the ocean. CDOM has proportionally more importance at attenuating light at short wavelengths and in more productive waters, phytoplankton absorption is relatively more important at the subsurface Chl a maximum, and water molecules have the greatest contribution when concentrations of other constituents are low, such as in the oligotrophic gyres. Scattering had less effect on attenuation, but since it is important for the amount and type of upwelling irradiance, it is crucial for setting sea surface reflectance. Strikingly, sensitivity experiments in which absorption by any of the optical constituents was increased led to a decrease in the size of the oligotrophic regions of the subtropical gyres: lateral nutrient supplies were enhanced as a result of decreasing high-latitude productivity. This new model that captures bio-optical feedbacks will be important for improving our understanding of the role of light and optical constituents on ocean biogeochemistry, especially in a changing environment. Further, resolving surface upwelling irradiance will make it easier to connect to satellite-derived products in the future. |
| first_indexed | 2024-09-23T10:10:31Z |
| format | Article |
| id | mit-1721.1/98105 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T10:10:31Z |
| publishDate | 2015 |
| publisher | Copernicus GmbH |
| record_format | dspace |
| spelling | mit-1721.1/981052024-05-15T05:27:02Z Capturing optically important constituents and properties in a marine biogeochemical and ecosystem model Hickman, A. E. Gregg, W. W. Mouw, C. B. Dutkiewicz, Stephanie Jahn, Oliver Follows, Michael J Massachusetts Institute of Technology. Center for Global Change Science Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Dutkiewicz, Stephanie Jahn, Oliver Follows, Michael J. We present a numerical model of the ocean that couples a three-stream radiative transfer component with a marine biogeochemical–ecosystem component in a dynamic three-dimensional physical framework. The radiative transfer component resolves the penetration of spectral irradiance as it is absorbed and scattered within the water column. We explicitly include the effect of several optically important water constituents (different phytoplankton functional types; detrital particles; and coloured dissolved organic matter, CDOM). The model is evaluated against in situ-observed and satellite-derived products. In particular we compare to concurrently measured biogeochemical, ecosystem, and optical data along a meridional transect of the Atlantic Ocean. The simulation captures the patterns and magnitudes of these data, and estimates surface upwelling irradiance analogous to that observed by ocean colour satellite instruments. We find that incorporating the different optically important constituents explicitly and including spectral irradiance was crucial to capture the variability in the depth of the subsurface chlorophyll a (Chl a) maximum. We conduct a series of sensitivity experiments to demonstrate, globally, the relative importance of each of the water constituents, as well as the crucial feedbacks between the light field, the relative fitness of phytoplankton types, and the biogeochemistry of the ocean. CDOM has proportionally more importance at attenuating light at short wavelengths and in more productive waters, phytoplankton absorption is relatively more important at the subsurface Chl a maximum, and water molecules have the greatest contribution when concentrations of other constituents are low, such as in the oligotrophic gyres. Scattering had less effect on attenuation, but since it is important for the amount and type of upwelling irradiance, it is crucial for setting sea surface reflectance. Strikingly, sensitivity experiments in which absorption by any of the optical constituents was increased led to a decrease in the size of the oligotrophic regions of the subtropical gyres: lateral nutrient supplies were enhanced as a result of decreasing high-latitude productivity. This new model that captures bio-optical feedbacks will be important for improving our understanding of the role of light and optical constituents on ocean biogeochemistry, especially in a changing environment. Further, resolving surface upwelling irradiance will make it easier to connect to satellite-derived products in the future. United States. National Aeronautics and Space Administration (NNX13AC34G) Natural Environment Research Council (Great Britain) (NE/H015930/2) National Science Foundation (U.S.) (OCE1434007) National Science Foundation (U.S.) (OCE1155295) Gordon and Betty Moore Foundation 2015-08-19T17:45:46Z 2015-08-19T17:45:46Z 2015-07 2015-06 Article http://purl.org/eprint/type/JournalArticle 1726-4189 http://hdl.handle.net/1721.1/98105 Dutkiewicz, S., A. E. Hickman, O. Jahn, W. W. Gregg, C. B. Mouw, and M. J. Follows. “Capturing Optically Important Constituents and Properties in a Marine Biogeochemical and Ecosystem Model.” Biogeosciences 12, no. 14 (2015): 4447–4481. https://orcid.org/0000-0002-3102-0341 en_US http://dx.doi.org/10.5194/bg-12-4447-2015 Biogeosciences Creative Commons Attribution http://creativecommons.org/licenses/by/3.0/ application/pdf Copernicus GmbH Copernicus Publications |
| spellingShingle | Hickman, A. E. Gregg, W. W. Mouw, C. B. Dutkiewicz, Stephanie Jahn, Oliver Follows, Michael J Capturing optically important constituents and properties in a marine biogeochemical and ecosystem model |
| title | Capturing optically important constituents and properties in a marine biogeochemical and ecosystem model |
| title_full | Capturing optically important constituents and properties in a marine biogeochemical and ecosystem model |
| title_fullStr | Capturing optically important constituents and properties in a marine biogeochemical and ecosystem model |
| title_full_unstemmed | Capturing optically important constituents and properties in a marine biogeochemical and ecosystem model |
| title_short | Capturing optically important constituents and properties in a marine biogeochemical and ecosystem model |
| title_sort | capturing optically important constituents and properties in a marine biogeochemical and ecosystem model |
| url | http://hdl.handle.net/1721.1/98105 https://orcid.org/0000-0002-3102-0341 |
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