Executive Summary#
Overview#
A new hindcast version of the Cook Inlet Operational Forecast System (CIOFS) model 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 project[1], in which a similar CIOFS model was with different freshwater forcing, and found that the model was severely lacking in freshwater in the system. These two models are compared in detail in the present report.
Key Outcomes#
The CIOFS Freshwater model output is similar to the CIOFS Hindcast output in the sense that they have the same grid resolution, and they have similar temperature and currents fields overall. However, much more freshwater is input to CIOFS Freshwater, and the effect of this is clear in the model output. It is visible in the salinity fields, including monthly surface salinity means, and comes out in comparisons with the CTD transects, many of which have much higher skill scores for CIOFS Freshwater. It is also clear in the drifter simulations that are in the Inlet and close enough to the surface to interact with freshwater, with the 7.5m drifters and shallower. 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.