Summary and Recommendations#
Summary#
A new hindcast version of the Cook Inlet Operational Forecast System (CIOFS) model (the CIOFS Freshwater model1) has been run with improved freshwater forcing for two time period: 2003–2006 and 2012–2014, selected to overlap with the maximum amount of historical data. This project follows from the previous hindcast CIOFS model project2, in which a similar CIOFS model (the CIOFS Hindcast model3) was run with only gauged rivers for freshwater forcing. That project found that the model was severely lacking freshwater in the system. These two models are compared in detail in the present report.
Key Outcomes#
Because much more freshwater is input to the newer model, salinity is captured much more accurately in the CIOFS Freshwater model, as compared with CIOFS Hindcast. The impact is also seen in the drifter simulations that are at 7.5m and shallower, which are close enough to the surface to be impacted by the presence of freshwater. For these drifter simulations, the CIOFS Freshwater particle tracks are more likely to follow the in situ drifter than the CIOFS Hindcast are, and that is borne out in the area-based skill scores found. Subtidal sea surface height for CIOFS Freshwater is also improved, demonstrating how this measure is impacted by the freshwater input. Temperature is also improved in the CIOFS Freshwater model, but only by a small margin.
Recommendations#
Given the success and large improvements seen in the CIOFS Freshwater version of the CIOFS model, the time range of the simulation should be expanded as long as possible, to something similar as the CIOFS Hindcast 1999–2022. When running a new long simulation, it would also be a good time to make other improvements in the model setup, such as improved stretching in the vertical grid, improved tracer advection, and improved turbulence closure scheme. Additionally, another model such as the Global Ocean Physics Reanalysis model (GLORYS12V1) should be evaluated a possible alternative for forcing the horizontal open boundaries.
- 1
CIOFS Freshwater visualization: https://portal.aoos.org/#module-metadata/43596105-4a50-4528-985f-bb65e1c08e2c
- 2
CIOFS Hindcast report: https://ciofs.axds.co/
- 3
CIOFS Hindcast visualization: https://portal.aoos.org/#metadata/7840770a-c04f-4b37-aba4-12094c8e1a5a/