Resolving frontal structures: on the payoff using a less diffusive but computationally more expensive advection scheme
Authored by Ute Daewel, Corinna Schrum, Knut Barthel, Dhanya Pushpadas, Marius Arthun, Henning Wehde
Date Published: 2012
DOI: 10.1007/s10236-012-0578-9
Sponsors:
European Union
Norwegian Research Council (NRF)
International Council of the Exploration of the Sea (ICES)
Platforms:
No platforms listed
Model Documentation:
Other Narrative
Mathematical description
Model Code URLs:
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Abstract
This article presents some advantages using a shape-preserving total
variation diminishing (TVD) advection scheme in an ecosystem model. The
superbee flux-limiter has been used to the second-order Lax-Wendroff
advection scheme to make it TVD. We performed simulations for three
shelf sea regions with different characteristic time scales, namely, the
North Sea, the Barents Sea, and the Baltic Sea. To explore the
advantages, we also performed reference runs with the much simpler and
computationally cheaper upwind advection scheme. Frontal structures are
much better resolved with the TVD scheme. The bottom salinity in the
Baltic Sea stays at realistic values throughout the 10-year simulation
with the TVD scheme, while with the upwind scheme, it drifts towards
lower values and the permanent haline stratification in the Baltic is
almost completely eroded within one seasonal cycle. Only when applying
TVD for both the vertical and horizontal advections the model succeeded
to preserve haline stratification in the decadal simulation. Lower
trophic level patterns are far better reproduced with the TVD scheme, and for the estimated cod larval survival, the advantages seem to be
even stronger. Simulations using the TVD-derived prey fields identified
distinct regions such as Dogger Bank to favor potential larvae survival
(PLS), which did not appear as particularly favorable in the upstream
simulations. The TVD scheme needs about 25 \% more time on the central
processing unit (CPU) in case of a pure hydrodynamic setup with only two
scalar state variables (Barents Sea application). The additional CPU
time cost increases for a coupled physical-biological model application
with a large number of state variables. However, this is more than
compensated by all the advantages found, and, hence, we conclude that it
is worthwhile to use the TVD scheme in our ecosystem model.
Tags
individual-based models
Water
Ecosystem model
Environmental variability
Marginal ice-zone
Southern north-sea
Baltic sea
Barents sea
Hyperbolic conservation-laws
High-resolution
schemes