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Puget Sound Georgia Basin Model

Hydrodynamic Model Validation and Error Analysis

Tide and current data stations

Six real-time tidal stations are maintained by the National Oceanic and Atmospheric Administration (NOAA) throughout the Straits and Puget Sound. Velocity data on the other hand are quite limited in Puget Sound as well as Georgia Basin regions of Salish Sea. Acoustic Doppler current profiler (ADCP) data in South Puget Sound (Roberts et al. 2008) as well as in Skagit Bay and Swinomish Channel (Yang and Khangaonkar 2010) were used for original model calibration. Monthly T/S profiles collected by the Washington State Department of Ecology as part of its ambient monitoring program throughout Puget Sound were also used. Hydrodynamic model calibration was conducted using Year 2006 data and has been discussed by Khangaonkar et al. (2011a) and Khangaonkar et al. (2012) and more recently in Khangaonkar et al. (2017a).

Model validation was conducted using Year 2014 data for water surface elevation, temperature and salinity using nine tide stations (X-Tide stations, Flater 1996) and the same 24 water quality stations maintained by Ecology. Relative water-surface elevation errors were less than 10% at all stations within Puget Sound in U.S. waters. Domain-wide temperature (T) RMSE was 0.76ºC with a bias of -0.27ºC. The domain-wide salinity (S) error was 0.97 ppt with a bias of -0.12 ppt. Model skill scores were also high for T and S with Wilmott Skill Score (WSS) values of 0.95 and 0.84, respectively. The Salish Sea Model validation is described in Khangaonkar et. al. (2018 under review).

Figure below shows (a) Sea surface temperature and (b) Salinity contour plots for representative days in spring (March), summer (June), fall (September), and winter (December) 2014. The influence of the Fraser River plume on sea surface T and S is noticeable in all seasons. Furthermore, monitoring data shows that sea surface temperatures in the Strait of Georgia and Hood Canal region warm up earlier than other sub-basins and are captured well by the model.


Validation Example

Examples of model validation results with comparison to observed data for Year 2006 effort are shown below along with error analysis tables.

(a) Time series plots for water-surface elevation and currents.


(b) Error analysis tables for water-surface elevation and currents.

Water-Surface Elevation




(c) Salinity and temperature time series and profiles.


(d) Salinity and temperature error analysis table.




Salish Sea Model Overview

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