Improving ocean reanalyses of observationally sparse regions with transfer learning

Abstract Oceanic subsurface observations are sparse and lead to large uncertainties in any model-based estimate. We investigate the applicability of transfer learning based neural networks to reconstruct North Atlantic temperatures in times with sparse observations. Our network is trained on a time...

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Main Authors: Simon Lentz, Sebastian Brune, Christopher Kadow, Johanna Baehr
Format: Article
Language:English
Published: Nature Portfolio 2025-01-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-86374-4
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author Simon Lentz
Sebastian Brune
Christopher Kadow
Johanna Baehr
author_facet Simon Lentz
Sebastian Brune
Christopher Kadow
Johanna Baehr
author_sort Simon Lentz
collection DOAJ
description Abstract Oceanic subsurface observations are sparse and lead to large uncertainties in any model-based estimate. We investigate the applicability of transfer learning based neural networks to reconstruct North Atlantic temperatures in times with sparse observations. Our network is trained on a time period with abundant observations to learn realistic physical behavior. Evaluating it within a consistent data assimilation framework, this network learns and reproduces its training data’s physical patterns. Additionally, the network is able to transfer these patterns towards a historical ocean heat content estimate in times with sparse observations. Consequently, with infrequent input data, machine learning reconstructions exhibit similar physical structures, while correcting for known errors compared to state-of-the-art data assimilation products. In this manner, transfer learning can impact the initialization and evaluation of climate hindcasts. Furthermore, by exhibiting the capability to accurately transfer results from high to low-frequencies, transfer learning based neural networks showcase their relevance in mixed-frequency measurements beyond climate science.
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spelling doaj-art-6ee8524444074228ab605ce58e5ae2a12025-01-26T12:29:26ZengNature PortfolioScientific Reports2045-23222025-01-011511810.1038/s41598-025-86374-4Improving ocean reanalyses of observationally sparse regions with transfer learningSimon Lentz0Sebastian Brune1Christopher Kadow2Johanna Baehr3Institute of Oceanography, Center for Earth System Sustainability, Universität HamburgInstitute of Oceanography, Center for Earth System Sustainability, Universität HamburgGerman Climate Computing Centre, DKRZInstitute of Oceanography, Center for Earth System Sustainability, Universität HamburgAbstract Oceanic subsurface observations are sparse and lead to large uncertainties in any model-based estimate. We investigate the applicability of transfer learning based neural networks to reconstruct North Atlantic temperatures in times with sparse observations. Our network is trained on a time period with abundant observations to learn realistic physical behavior. Evaluating it within a consistent data assimilation framework, this network learns and reproduces its training data’s physical patterns. Additionally, the network is able to transfer these patterns towards a historical ocean heat content estimate in times with sparse observations. Consequently, with infrequent input data, machine learning reconstructions exhibit similar physical structures, while correcting for known errors compared to state-of-the-art data assimilation products. In this manner, transfer learning can impact the initialization and evaluation of climate hindcasts. Furthermore, by exhibiting the capability to accurately transfer results from high to low-frequencies, transfer learning based neural networks showcase their relevance in mixed-frequency measurements beyond climate science.https://doi.org/10.1038/s41598-025-86374-4Transfer learningConvolutional U-netsPhysics-informedClimate hindcast initializationOcean heat content
spellingShingle Simon Lentz
Sebastian Brune
Christopher Kadow
Johanna Baehr
Improving ocean reanalyses of observationally sparse regions with transfer learning
Scientific Reports
Transfer learning
Convolutional U-nets
Physics-informed
Climate hindcast initialization
Ocean heat content
title Improving ocean reanalyses of observationally sparse regions with transfer learning
title_full Improving ocean reanalyses of observationally sparse regions with transfer learning
title_fullStr Improving ocean reanalyses of observationally sparse regions with transfer learning
title_full_unstemmed Improving ocean reanalyses of observationally sparse regions with transfer learning
title_short Improving ocean reanalyses of observationally sparse regions with transfer learning
title_sort improving ocean reanalyses of observationally sparse regions with transfer learning
topic Transfer learning
Convolutional U-nets
Physics-informed
Climate hindcast initialization
Ocean heat content
url https://doi.org/10.1038/s41598-025-86374-4
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AT christopherkadow improvingoceanreanalysesofobservationallysparseregionswithtransferlearning
AT johannabaehr improvingoceanreanalysesofobservationallysparseregionswithtransferlearning