Seasonal and interannual variability of the Columbia River plume: A perspective enabled by multiyear simulation databases

Abstract

[1] As integral capability within an end-to-end observatory for the Columbia River estuary-plume-shelf system, we routinely create simulation databases of 3-D baroclinic circulation with unstructured grid models SELFE (Semi-implicit Eulerian-Lagrangian Finite Element) and ELCIRC (Eulerian-Lagrangian Circulation). Here, 1999-2006 simulations are used to study plume variability at multiple temporal scales: interannual, seasonal, and event scale. Time series of plume metrics, together with climatology and anomalies of surface salinity, suggest that simulations usefully capture key features of plume dynamics. In particular, simulations capture seasonal variability around two known trends: a coastally attached northward winter plume and a detached southward summer plume. Results show significant interannual variability of the plume orientation and extent, with potential implications on the variability of productivity in the system. An empirical orthogonal function analysis confirms that a bidirectional plume is prevalent in summer, showing that the result holds true regardless of interannual variability. Short-term bidirectional plumes, previously observed or modeled only in summer, can also occasionally develop in winter as a result of episodically strong upwelling-favorable winds. Across years, the predominantly coastal attached northward plume in late fall and winter is found to separate frequently from the coast, during wind relaxation events or weak wind reversals. Multiple skill scores are used to evaluate the quality of the simulations against earlier circulation databases and data. Analysis of root-mean-square error and bias suggests overall superiority of SELFE-generated over ELCIRC-generated simulation databases, but the generality of the conclusions is limited by (1) models not being the only difference between simulation databases and (2) no model prevailing across all error metrics.

Estimating behavior in a black box: how coastal oceanographic dynamics influence yearling Chinook salmon marine growth and migration behaviors

“…Our analysis clearly shows that interannual variation in coastal currents (e.g., Burla et al 2010) results in altered yearling Chinook salmon migration behavior. If salmon possess a "map sense" or the ability to know their ocean location (Putman et al 2013, Putman et al 2014, then our results suggest they use that sense in altering swim speed and angle to counteract the effects of coastal currents.…”

“…Our first oceanographic modeling tool was the Virtual Columbia River, which provides a high-resolution, spatially explicit description of 3-D, river-to-ocean circulation and water properties in the Columbia River and plume (Baptista et al 2008, Burla et al 2010, CMOP 2013. Virtual Columbia River simulations were run using SELFE (semi-implicit, Eulerian-Lagrangian, finite-element).…”

Evidence for multiple navigational sensory capabilities of Chinook salmon

“…We defined ocean circulation near the Columbia River and the coastal ocean from 1 March through 30 September using the Virtual Columbia River modeling system (CMOP 2013), which provides a high-resolution description of 3-dimensional (3D) river-toocean circulation and water properties in the Columbia River and plume , Burla et al 2010b.…”

“…These consisted of a continuity equation, conservation equations for momentum, salinity, and heat, and an equation of state, which used a finite-element method applied on an unstructured, 3-node triangular grid. The skill of these simulations had been previously assessed through quantitative comparison against observations of water level, salinity, and temperature from the Science and Technology University Research Network (SATURN) collaboratory (Baptista et al 2005, Burla et al 2010b.…”

Estuarine Habitats for Juvenile Salmon in the Tidally-Influenced Lower Columbia River and Estuary : Reporting Period September 15, 2008 through May 31, 2009.

“…SATURN relies on 3D numerical models [2,3] to systematically simulate and understand baroclinic circulation in the Columbia River estuary-plume-shelf system [4][5][6][7] (Fig. 1).…”