An observation-based evaluation and ranking of historical Earth System Model simulations for regional downscaling in the northwest North Atlantic Ocean
Continental shelf regions in the ocean play an important role in the global cycling of carbon and nutrients but their responses to global change are understudied. Global Earth System Models (ESM), as essential tools for building understanding of ocean biogeochemistry, are used extensively and routin...
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ftcopernicus:oai:publications.copernicus.org:bgd86957 2023-05-15T17:31:38+02:00 An observation-based evaluation and ranking of historical Earth System Model simulations for regional downscaling in the northwest North Atlantic Ocean Laurent, Arnaud Fennel, Katja Kuhn, Angela 2020-07-17 application/pdf https://doi.org/10.5194/bg-2020-265 https://www.biogeosciences-discuss.net/bg-2020-265/ eng eng doi:10.5194/bg-2020-265 https://www.biogeosciences-discuss.net/bg-2020-265/ eISSN: 1726-4189 Text 2020 ftcopernicus https://doi.org/10.5194/bg-2020-265 2020-07-20T16:21:59Z Continental shelf regions in the ocean play an important role in the global cycling of carbon and nutrients but their responses to global change are understudied. Global Earth System Models (ESM), as essential tools for building understanding of ocean biogeochemistry, are used extensively and routinely for projections of future climate states; however, their relatively coarse spatial resolution is likely not appropriate for accurately representing the complex patterns of circulation and elemental fluxes on the shelves along ocean margins. Here, we compared 29 ESMs used in the IPCC’s Assessment Rounds (AR) 5 and 6 and a regional biogeochemical model for the northwest North Atlantic (NWA) shelf to assess their ability to reproduce observations of temperature, nitrate, and chlorophyll. The NWA region is biologically productive, influenced by the large-scale Gulf Stream and Labrador Current systems, and particularly sensitive to climate change. Most ESMs compare relatively poorly to observed nitrate and chlorophyll and show differences with observed temperature due to spatial mismatches in their large-scale circulation. Model-simulated nitrate and chlorophyll compare better with available observations in AR6 than in AR5, but none of the models performs equally well for all 3 parameters. The ensemble means of all ESMs, and of the five best performing ESMs, strongly underestimate observed chlorophyll and nitrate. The regional model has a much higher spatial resolution and reproduces the observations significantly better than any of the ESMs. It also simulates reasonably well vertically resolved observations from gliders and bi-monthly ship-based monitoring observations. A ranking of the ESMs suggests that the top 3 models are appropriate as boundary forcing for regional projections of future changes in the NWA region. Text North Atlantic Copernicus Publications: E-Journals |
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Copernicus Publications: E-Journals |
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English |
description |
Continental shelf regions in the ocean play an important role in the global cycling of carbon and nutrients but their responses to global change are understudied. Global Earth System Models (ESM), as essential tools for building understanding of ocean biogeochemistry, are used extensively and routinely for projections of future climate states; however, their relatively coarse spatial resolution is likely not appropriate for accurately representing the complex patterns of circulation and elemental fluxes on the shelves along ocean margins. Here, we compared 29 ESMs used in the IPCC’s Assessment Rounds (AR) 5 and 6 and a regional biogeochemical model for the northwest North Atlantic (NWA) shelf to assess their ability to reproduce observations of temperature, nitrate, and chlorophyll. The NWA region is biologically productive, influenced by the large-scale Gulf Stream and Labrador Current systems, and particularly sensitive to climate change. Most ESMs compare relatively poorly to observed nitrate and chlorophyll and show differences with observed temperature due to spatial mismatches in their large-scale circulation. Model-simulated nitrate and chlorophyll compare better with available observations in AR6 than in AR5, but none of the models performs equally well for all 3 parameters. The ensemble means of all ESMs, and of the five best performing ESMs, strongly underestimate observed chlorophyll and nitrate. The regional model has a much higher spatial resolution and reproduces the observations significantly better than any of the ESMs. It also simulates reasonably well vertically resolved observations from gliders and bi-monthly ship-based monitoring observations. A ranking of the ESMs suggests that the top 3 models are appropriate as boundary forcing for regional projections of future changes in the NWA region. |
format |
Text |
author |
Laurent, Arnaud Fennel, Katja Kuhn, Angela |
spellingShingle |
Laurent, Arnaud Fennel, Katja Kuhn, Angela An observation-based evaluation and ranking of historical Earth System Model simulations for regional downscaling in the northwest North Atlantic Ocean |
author_facet |
Laurent, Arnaud Fennel, Katja Kuhn, Angela |
author_sort |
Laurent, Arnaud |
title |
An observation-based evaluation and ranking of historical Earth System Model simulations for regional downscaling in the northwest North Atlantic Ocean |
title_short |
An observation-based evaluation and ranking of historical Earth System Model simulations for regional downscaling in the northwest North Atlantic Ocean |
title_full |
An observation-based evaluation and ranking of historical Earth System Model simulations for regional downscaling in the northwest North Atlantic Ocean |
title_fullStr |
An observation-based evaluation and ranking of historical Earth System Model simulations for regional downscaling in the northwest North Atlantic Ocean |
title_full_unstemmed |
An observation-based evaluation and ranking of historical Earth System Model simulations for regional downscaling in the northwest North Atlantic Ocean |
title_sort |
observation-based evaluation and ranking of historical earth system model simulations for regional downscaling in the northwest north atlantic ocean |
publishDate |
2020 |
url |
https://doi.org/10.5194/bg-2020-265 https://www.biogeosciences-discuss.net/bg-2020-265/ |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
eISSN: 1726-4189 |
op_relation |
doi:10.5194/bg-2020-265 https://www.biogeosciences-discuss.net/bg-2020-265/ |
op_doi |
https://doi.org/10.5194/bg-2020-265 |
_version_ |
1766129312846577664 |