HOTSSea v1: a NEMO-based physical Hindcast of the Salish Sea (1980–2018) supporting ecosystem model development

Oldford, Greig, Jarníková, Tereza, Christensen, Villy and Dunphy, Michael (2025) HOTSSea v1: a NEMO-based physical Hindcast of the Salish Sea (1980–2018) supporting ecosystem model development. Geoscientific Model Development, 18 (2). pp. 211-237. ISSN 1991-9603

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Abstract

Decadal-scale oceanographic, environmental, and ecological changes have been reported in the Salish Sea, an ecologically productive inland sea in the northeast Pacific that supports the economies and cultures of millions of people. However, there are substantial data gaps related to physical water properties that make it difficult to evaluate trends and the pathways of effects between physical ocean water properties and the productivity of marine ecosystems. With the aim of addressing these gaps, we present the Hindcast of the Salish Sea (HOTSSea) v1, a 3D physical oceanographic model developed using the Nucleus for European Modelling of the Ocean (NEMO) ocean engine, with temporal coverage from 1980–2018. We used an experimental approach to incrementally assess sensitivity to atmospheric and ocean reanalysis products used for boundary forcings and to the horizontal discretisation of the model grid (∼ 1.5 km). Biases inherited from forcings were quantified, and a simple temperature bias correction factor applied at one ocean boundary was found to substantially improve model skill. Evaluation of salinity and temperature indicates performance is best in the Strait of Georgia. Relatively large biases occur in near-surface waters, especially in subdomains with topography narrower than the model grid's horizontal resolution. However, we demonstrated that the model simulates temperature anomalies and a secular warming trend over the entire water column in general agreement with observations. HOTSSea v1 provided a first look at spatially and temporally heterogenous ocean temperature trends throughout the northern and central part of the domain where observations are sparse. Overall, despite the biases inherited from forcings and a relatively coarse horizontal discretisation, HOTSSea v1 performs well at representing temperature and salinity at the spatial–temporal scales needed to support research related to decadal-scale climate effects on marine ecosystems, fish, and fisheries. We conclude by underscoring the need to further extend the hindcast to capture a regime shift that occurred in the 1970s.

Item Type:	Article
Additional Information:	Code and data availability: HOTSSea is based on the NEMO source code version 3.6 (https://doi.org/10.5281/zenodo.1464816, Madec et al., 2017; subversion trunk revision rev10584), released under the open-source CeCILL license (https://cecill.info, last access: 7 March 2024). The HOTSSea v1 configuration files and source code used for analysis and visuals in the present article have been archived at https://doi.org/10.5281/zenodo.13887813 (Oldford, 2024a). Forcings and observations prepared for the model are provided separately due to space limits, with HRDPS at https://doi.org/10.5281/zenodo.12193924 (Oldford and Dunphy, 2024a); RDRS at https://doi.org/10.5281/zenodo.12206291 (ECCC, 2024); and ERA5, CIOPS, runoff, and observational data at https://doi.org/ 10.5281/zenodo.12312769 (Oldford and Dunphy, 2024b). Raw outputs are currently stored on a server without necessary bandwidth to make them publicly available given the file sizes; however, they can be made available by contacting the authors. Depth-averaged, monthly mean outputs are available online at https://doi.org/10.5281/zenodo.13942109 (Oldford, 2024b). The processed monthly HOTSSea outputs may be accessed by installing the pacea opensource R package, which aims to reduce the burden of wrangling such data for fisheries stock assessments and other applications (https://doi.org/10.5281/zenodo.13840804, Edwards et al., 2024).
Uncontrolled Keywords:	covid-19,face mask,pandemic,prevention,respiratory viral infection,rapid review,sdg 13 - climate action,sdg 14 - life below water,sdg 15 - life on land ,/dk/atira/pure/sustainabledevelopmentgoals/climate_action
Faculty \ School:	Faculty of Science > School of Environmental Sciences
UEA Research Groups:	University of East Anglia Schools > Faculty of Science > Tyndall Centre for Climate Change Research Faculty of Science > Research Centres > Tyndall Centre for Climate Change Research
Depositing User:	LivePure Connector
Date Deposited:	12 Feb 2026 10:30
Last Modified:	16 Feb 2026 01:28
URI:	https://ueaeprints.uea.ac.uk/id/eprint/101926
DOI:	10.5194/gmd-18-211-2025

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