Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers
Conventional integration of earth system and ocean models can accrue considerable computational expenses, particularly for marine biogeochemical applications. “Offline” numerical schemes in which only the biogeochemical tracers are time-stepped and transported using a pre-computed circulation field...
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| Format: | Journal article |
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Copernicus Publications
2017
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| author | Kvale, K Khatiwala, S Dietze, H Kriest, I Oschlies, A |
| author_facet | Kvale, K Khatiwala, S Dietze, H Kriest, I Oschlies, A |
| author_sort | Kvale, K |
| collection | OXFORD |
| description | Conventional integration of earth system and ocean models can accrue considerable computational expenses, particularly for marine biogeochemical applications. “Offline” numerical schemes in which only the biogeochemical tracers are time-stepped and transported using a pre-computed circulation field can substantially reduce the burden and are thus an attractive alternative. One such scheme is the “transport matrix method” (TMM), which represents tracer transport as a sequence of sparse matrix-vector products that can be performed efficiently on distributed-memory computers. While the TMM has been used for a variety of geochemical and biogeochemical studies, to date the resulting solutions have not been comprehensively assessed against their “online” counterparts. Here, we present a detailed comparison of the two. It is based on simulations of the state-of-the-art biogeochemical sub-model embedded within the widely-used University of Victoria Earth System Climate Model (UVic ESCM). Transport matrices were extracted for an equilibrium run of the physical model and subsequently used to integrate the biogeochemical model offline to equilibrium. The identical biogeochemical model was also run online. Our simulations show that offline integration introduces some bias to biogeochemical quantities through the omission of the polar filtering used in UVic ESCM, and in the offline application of time-dependent forcing fields, with high latitudes showing the largest differences with respect to the online model. Differences in other regions and in the seasonality of nutrients and phytoplankton distributions are found to be relatively minor, giving confidence that the TMM is a reliable tool for offline integration of complex biogeochemical models. Moreover, while UVic ESCM is a serial code, the TMM can be run on a parallel machine with no change to the underlying biogeochemical code, thus providing orders of magnitude speed-up over the online model. |
| first_indexed | 2024-03-07T04:18:58Z |
| format | Journal article |
| id | oxford-uuid:ca59f2db-b977-4817-8b59-ebe274ab5e9d |
| institution | University of Oxford |
| last_indexed | 2024-03-07T04:18:58Z |
| publishDate | 2017 |
| publisher | Copernicus Publications |
| record_format | dspace |
| spelling | oxford-uuid:ca59f2db-b977-4817-8b59-ebe274ab5e9d2022-03-27T07:06:52ZEvaluation of the transport matrix method for simulation of ocean biogeochemical tracersJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:ca59f2db-b977-4817-8b59-ebe274ab5e9dSymplectic Elements at OxfordCopernicus Publications2017Kvale, KKhatiwala, SDietze, HKriest, IOschlies, AConventional integration of earth system and ocean models can accrue considerable computational expenses, particularly for marine biogeochemical applications. “Offline” numerical schemes in which only the biogeochemical tracers are time-stepped and transported using a pre-computed circulation field can substantially reduce the burden and are thus an attractive alternative. One such scheme is the “transport matrix method” (TMM), which represents tracer transport as a sequence of sparse matrix-vector products that can be performed efficiently on distributed-memory computers. While the TMM has been used for a variety of geochemical and biogeochemical studies, to date the resulting solutions have not been comprehensively assessed against their “online” counterparts. Here, we present a detailed comparison of the two. It is based on simulations of the state-of-the-art biogeochemical sub-model embedded within the widely-used University of Victoria Earth System Climate Model (UVic ESCM). Transport matrices were extracted for an equilibrium run of the physical model and subsequently used to integrate the biogeochemical model offline to equilibrium. The identical biogeochemical model was also run online. Our simulations show that offline integration introduces some bias to biogeochemical quantities through the omission of the polar filtering used in UVic ESCM, and in the offline application of time-dependent forcing fields, with high latitudes showing the largest differences with respect to the online model. Differences in other regions and in the seasonality of nutrients and phytoplankton distributions are found to be relatively minor, giving confidence that the TMM is a reliable tool for offline integration of complex biogeochemical models. Moreover, while UVic ESCM is a serial code, the TMM can be run on a parallel machine with no change to the underlying biogeochemical code, thus providing orders of magnitude speed-up over the online model. |
| spellingShingle | Kvale, K Khatiwala, S Dietze, H Kriest, I Oschlies, A Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers |
| title | Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers |
| title_full | Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers |
| title_fullStr | Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers |
| title_full_unstemmed | Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers |
| title_short | Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers |
| title_sort | evaluation of the transport matrix method for simulation of ocean biogeochemical tracers |
| work_keys_str_mv | AT kvalek evaluationofthetransportmatrixmethodforsimulationofoceanbiogeochemicaltracers AT khatiwalas evaluationofthetransportmatrixmethodforsimulationofoceanbiogeochemicaltracers AT dietzeh evaluationofthetransportmatrixmethodforsimulationofoceanbiogeochemicaltracers AT kriesti evaluationofthetransportmatrixmethodforsimulationofoceanbiogeochemicaltracers AT oschliesa evaluationofthetransportmatrixmethodforsimulationofoceanbiogeochemicaltracers |