You are here

About DB14

In-brief: This river-to-shelf simulation database is actively maintained, and constitutes the reference for multi-year representation of plume dynamics and variability. It provides ocean boundary conditions for the estuary-only simulation database DB16.

Skill assessment: There is a substantial improvement in plume salinity relatively to DB11, documented in Burla et al. 2010. Representation of shipboard salinity observations in the plume is robust enough to assist post-cruise interpretation. However, plume responsiveness to wind changes could be improved (perhaps through adjustment of the mixing length in the turbulence closure scheme). While much improved over DB11, DB14 still consistently underestimates salinity intrusion in the estuary (DB16 should be used instead). Temperature skill is still generally low (DB22, in development, is designed to improve this skill).

See skill comparison across databases.

Relevant publications: Burla et al. 2010

Simulation settings: (for additional detail, see input files)

  • Circulation code: SELFE v1.4a (hydrostatic model).
  • Numerical grid: The triangle-based unstructured horizontal grid extends from the ocean to Beaver Army terminal, and has 20641 nodes and 38960 elements. SZ-coordinate vertical grid with 36 S levels and 18 Z levels.
  • Time step: 90s
  • Algorithm for scalar transport: Upwind scheme
  • Turbulence closure: Turbulent viscosity and diffusivity are computed with a k-kl turbulent closure with Kantha & Clayson’s stability function, and are bounded as follows: minimum of 10-6 m2/s; maximum of 10-3 m2/s in the estuary and of 10 m2/s in the shelf.
  • Bottom friction: Variable bottom friction. Drag coefficients are 0.002 downstream of the Astoria-Megler bridge, 0.005 upstream of Tongue Point, and vary linearly in-between.
  • River forcing: Discharge and temperature from USGS observations at Beaver Army Terminal, with gaps filled through modeling (for discharge) and correlations with other stations (for temperature).
  • Ocean forcing: Initial conditions from NCOM. Salinity and temperature boundary conditions from same source, applied through nudging over an extended shelf region, with a 0.05 % (2-day) relaxation factor.
  • Atmospheric forcing: heat and momentum exchange parameters are interpolated from external models. Sources are NARRS from 1999-2003, ETA from 2004-2005, and NAM since 2006.
  • Heat exchange: Zeng et al.’s bulk aerodynamic similarity model is used to compute air-water exchange including shear stress and turbulent fluxes of sensible and latent heat.