Can wave coupling improve operational regional ocean forecasts for the north-west European Shelf?
<p>Operational ocean forecasts are typically produced by modelling systems run using a forced mode approach. The evolution of the ocean state is not directly influenced by surface waves, and the ocean dynamics are driven by an external source of meteorological data which are independent of the...
Main Authors: | , , , , , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2019-06-01
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Series: | Ocean Science |
Online Access: | https://www.ocean-sci.net/15/669/2019/os-15-669-2019.pdf |
Summary: | <p>Operational ocean forecasts are typically produced
by modelling systems run using a forced mode approach. The evolution of the
ocean state is not directly influenced by surface waves, and the ocean
dynamics are driven by an external source of meteorological data which are
independent of the ocean state. Model coupling provides one approach to
increase the extent to which ocean forecast systems can represent the
interactions and feedbacks between ocean, waves, and the atmosphere seen in
nature. This paper demonstrates the impact of improving how the effect of
waves on the momentum exchange across the ocean–atmosphere interface is
represented through ocean–wave coupling on the performance of an operational
regional ocean prediction system. This study focuses on the eddy-resolving
(1.5 km resolution) Atlantic Margin Model (AMM15) ocean model configuration
for the north-west European Shelf (NWS) region.</p>
<p>A series of 2-year duration forecast trials of the Copernicus Marine
Environment Monitoring Service (CMEMS) north-west European Shelf regional ocean
prediction system are analysed. The impact of including ocean–wave feedbacks
via dynamic coupling on the simulated ocean is discussed. The main
interactions included are the modification of surface stress by wave growth
and dissipation, Stokes–Coriolis forcing, and wave-height-dependent ocean
surface roughness. Given the relevance to operational forecasting, trials
with and without ocean data assimilation are considered.</p>
<p>Summary forecast metrics demonstrate that the ocean–wave coupled system is a
viable evolution for future operational implementation. When results are
considered in more depth, wave coupling was found to result in an annual
cycle of relatively warmer winter and cooler summer sea surface temperatures
for seasonally stratified regions of the NWS. This is driven by enhanced
mixing due to waves, and a deepening of the ocean mixed layer during summer.
The impact of wave coupling is shown to be reduced within the mixed layer
with assimilation of ocean observations. Evaluation of salinity and ocean
currents against profile measurements in the German Bight demonstrates
improved simulation with wave coupling relative to control simulations.
Further, evidence is provided of improvement to simulation of extremes of
sea surface height anomalies relative to coastal tide gauges.</p> |
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ISSN: | 1812-0784 1812-0792 |