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

Abstract. Decadal-scale oceanographic, environmental, and ecological changes have been reported in the Salish Sea, an ecologically productive and biodiverse inland sea in the northeast Pacific that supports the economies and cultures of millions of people; however, there are substantial observational gaps pertaining to physical water properties that make linkages between physical drivers and ecosystem effects difficult to ascertain. With the aim of addressing these gaps, we present the Hindcast of the Salish Sea (HOTSSea) v1 with temporal coverage from 1980–2018, developed using the NEMO ocean engine. An inter-model comparison and preliminary evaluation was performed to assess sensitivity to different atmospheric and ocean reanalysis products used for boundary forcings. Biases inherited from forcings were quantified and the effectiveness of a simple temperature bias correction factor applied at one ocean boundary was evaluated. Evaluation of salinity and temperature indicates performance is best in the Strait of Georgia where the model simulates temperature anomalies and a secular warming trend over the entire water column in general agreement with observations. Analyses of modelled ocean temperature trends throughout the northern and central part of the domain where model skill was high and where observations are relatively sparse yielded fresh insights, including that ocean temperature trends are spatially and temporally variable. HOTSSea v1 will support development of an end-to-end spatial-temporal ecosystem model for the Strait of Georgia and has potential for other research and management applications related to decadal-scale climate effects on marine ecosystems, fish, and fisheries.