Impact of operational model nesting approaches and inherent errors for coastal simulations

Brown, Jennifer ORCID: https://orcid.org/0000-0002-3894-4651; Norman, Danielle; Amoudry, Laurent; Souza, Alejandro. 2016 Impact of operational model nesting approaches and inherent errors for coastal simulations [in special issue: Coastal ocean modelling] Ocean Modelling, 107. 48-63. 10.1016/j.ocemod.2016.10.005

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© 2016 Elsevier B.V. This is the author’s version of a work that was accepted for publication in Ocean Modelling. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was be published in Ocean Modelling doi.org/10.1016/j.ocemod.2016.10.005
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Abstract/Summary

A region of freshwater influence (ROFI) under hypertidal conditions is used to demonstrate inherent problems for nested operational modelling systems. Such problems can impact the accurate simulation of freshwater export within shelf seas, so must be considered in coastal ocean modelling studies. In Liverpool Bay (our UK study site), freshwater inflow from 3 large estuaries forms a coastal front that moves in response to tides and winds. The cyclic occurrence of stratification and remixing is important for the biogeochemical cycles, as nutrient and pollutant loaded freshwater is introduced into the coastal system. Validation methods, using coastal observations from fixed moorings and cruise transects, are used to assess the simulation of the ROFI, through improved spatial structure and temporal variability of the front, as guidance for best practise model setup. A structured modelling system using a 180 m grid nested within a 1.8 km grid demonstrates how compensation for error at the coarser resolution can have an adverse impact on the nested, high resolution application. Using 2008, a year of typical calm and stormy periods with variable river influence, the sensitivities of the ROFI dynamics to initial and boundary conditions are investigated. It is shown that accurate representation of the initial water column structure is important at the regional scale and that the boundary conditions are most important at the coastal scale. Although increased grid resolution captures the frontal structure, the accuracy in frontal position is determined by the offshore boundary conditions and therefore the accuracy of the coarser regional model.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.ocemod.2016.10.005
Programmes:	NOC Programmes > Marine Physics and Ocean Climate
ISSN:	1463-5003
Additional Keywords:	ROFI; POLCOMS-GOTM; Liverpool Bay; model nesting; freshwater export; Initial and boundary conditions
NORA Subject Terms:	Marine Sciences
Date made live:	20 Oct 2016 08:45 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/514851

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1016/j.ocemod.2016.10.005

Programmes:

NOC Programmes > Marine Physics and Ocean Climate

ISSN:

1463-5003

Additional Keywords:

ROFI; POLCOMS-GOTM; Liverpool Bay; model nesting; freshwater export; Initial and boundary conditions

NORA Subject Terms:

Marine Sciences