Calibration of a simple and a complex model of global marine biogeochemistry
The assessment of the ocean biota's role in climate change is often carried out with global biogeochemical ocean models that contain many components and involve a high level of parametric uncertainty. Because many data that relate to tracers included in a model are only sparsely observed, as...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2017-11-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/14/4965/2017/bg-14-4965-2017.pdf |
| _version_ | 1818960988161966080 |
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| author | I. Kriest |
| author_facet | I. Kriest |
| author_sort | I. Kriest |
| collection | DOAJ |
| description | The assessment of the ocean biota's role in climate change is often carried
out with global biogeochemical ocean models that contain many components and
involve a high level of parametric uncertainty. Because many data that relate
to tracers included in a model are only sparsely observed, assessment of
model skill is often restricted to tracers that can be easily measured and
assembled. Examination of the models' fit to climatologies of inorganic
tracers, after the models have been spun up to steady state, is a common but
computationally expensive procedure to assess model performance and
reliability. Using new tools that have become available for global model
assessment and calibration in steady state, this paper examines two different
model types – a complex seven-component model (MOPS) and a very simple
four-component model (RetroMOPS) – for their fit to dissolved quantities.
Before comparing the models, a subset of their biogeochemical parameters has
been optimised against annual-mean nutrients and oxygen. Both model types fit
the observations almost equally well. The simple model contains only two
nutrients: oxygen and dissolved organic phosphorus (DOP). Its misfit and
large-scale tracer distributions are sensitive to the parameterisation of DOP
production and decay. The spatio-temporal decoupling of nitrogen and oxygen,
and processes involved in their uptake and release, renders oxygen and
nitrate valuable tracers for model calibration. In addition, the
non-conservative nature of these tracers (with respect to their upper
boundary condition) introduces the global bias (fixed nitrogen and oxygen
inventory) as a useful additional constraint on model parameters. Dissolved
organic phosphorus at the surface behaves antagonistically to phosphate, and
suggests that observations of this tracer – although difficult to measure –
may be an important asset for model calibration. |
| first_indexed | 2024-12-20T12:06:16Z |
| format | Article |
| id | doaj.art-d95c6542eca44c399f2f63dab9d7ffb1 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-20T12:06:16Z |
| publishDate | 2017-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-d95c6542eca44c399f2f63dab9d7ffb12022-12-21T19:41:23ZengCopernicus PublicationsBiogeosciences1726-41701726-41892017-11-01144965498410.5194/bg-14-4965-2017Calibration of a simple and a complex model of global marine biogeochemistryI. Kriest0GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Düsternbrooker Weg 20, 24105 Kiel, GermanyThe assessment of the ocean biota's role in climate change is often carried out with global biogeochemical ocean models that contain many components and involve a high level of parametric uncertainty. Because many data that relate to tracers included in a model are only sparsely observed, assessment of model skill is often restricted to tracers that can be easily measured and assembled. Examination of the models' fit to climatologies of inorganic tracers, after the models have been spun up to steady state, is a common but computationally expensive procedure to assess model performance and reliability. Using new tools that have become available for global model assessment and calibration in steady state, this paper examines two different model types – a complex seven-component model (MOPS) and a very simple four-component model (RetroMOPS) – for their fit to dissolved quantities. Before comparing the models, a subset of their biogeochemical parameters has been optimised against annual-mean nutrients and oxygen. Both model types fit the observations almost equally well. The simple model contains only two nutrients: oxygen and dissolved organic phosphorus (DOP). Its misfit and large-scale tracer distributions are sensitive to the parameterisation of DOP production and decay. The spatio-temporal decoupling of nitrogen and oxygen, and processes involved in their uptake and release, renders oxygen and nitrate valuable tracers for model calibration. In addition, the non-conservative nature of these tracers (with respect to their upper boundary condition) introduces the global bias (fixed nitrogen and oxygen inventory) as a useful additional constraint on model parameters. Dissolved organic phosphorus at the surface behaves antagonistically to phosphate, and suggests that observations of this tracer – although difficult to measure – may be an important asset for model calibration.https://www.biogeosciences.net/14/4965/2017/bg-14-4965-2017.pdf |
| spellingShingle | I. Kriest Calibration of a simple and a complex model of global marine biogeochemistry Biogeosciences |
| title | Calibration of a simple and a complex model of global marine biogeochemistry |
| title_full | Calibration of a simple and a complex model of global marine biogeochemistry |
| title_fullStr | Calibration of a simple and a complex model of global marine biogeochemistry |
| title_full_unstemmed | Calibration of a simple and a complex model of global marine biogeochemistry |
| title_short | Calibration of a simple and a complex model of global marine biogeochemistry |
| title_sort | calibration of a simple and a complex model of global marine biogeochemistry |
| url | https://www.biogeosciences.net/14/4965/2017/bg-14-4965-2017.pdf |
| work_keys_str_mv | AT ikriest calibrationofasimpleandacomplexmodelofglobalmarinebiogeochemistry |