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Ocean Science

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Oceanography, Ocean currents -- Observations, Surface waves (Water)



The predictability of the sea surface height expression of baroclinic tides is examined with 96h forecasts produced by the AMSEAS operational forecast model during 2013–2014. The phase-locked tide, both barotropic and baroclinic, is identified by harmonic analysis of the 2-year record and found to agree well with observations from tide gauges and satellite altimetry within the Caribbean Sea. The non-phase-locked baroclinic tide, which is created by timevariablemesoscalestratificationandcurrents,maybeidentified from residual sea level anomalies (SLAs) near the tidal frequencies. The predictability of the non-phase-locked tide is assessed by measuring the difference between a forecast – centeredat T+36, T+60,or T+84h–andthemodel’slater verifying analysis for the same time. Within the Caribbean Sea, where a baroclinic tidal sea level range of±5cm is typical, the forecast error for the non-phase-locked tidal SLA is correlatedwiththeforecasterrorforthesubtidal(mesoscale) SLA. Root mean square values of the former range from 0.5 to 2cm, while the latter ranges from 1 to 6cm, for a typical 84h forecast. The spatial and temporal variability of the forecast error is related to the dynamical origins of the nonphase-locked tide and is briefly surveyed within the model.


© Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License.



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