Loveday, B., Swart S., Storkey, D.
Abstract

Ocean models require independent datasets to verify forecast accuracy. Glider data, within an appropriate reference frame, can satisfy this constraint. In the present paper, profiles from the northwest Mediterranean Sea are re-gridded to allow evaluation of modelled deepwater formation episodes. Time-series analysis of temperature, salinity, mixed-layer depth and ocean heat content show that the simulated response to surface flux is consistent with observations and the evolution of convective events is well represented. However, discrepancies in the distributions of the simulated Levantine Intermediate Water (LIW) and western Mediterranean deep water (WMDW) remain. A new ‘sweep’ methodology, developed in the present paper, indicates that the location and duration of the  simulated convective events are consistent with that observed, but spatial variability is underrepresented. Variogram analysis ascribes integral scales similar to those observed for the mixed-layer depth, but suggests that simulated scalar fields are too diffuse. The ability to maximise the separation of temporal and spatial variability, inherent in this new methodology, confirms that glider data is suitable for validating high-resolution ocean models.

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Schematic overview of convection phases: (a) isopycnal doming and erosion of stratification during pre-conditioning; (b) wind-driven surface heat loss deepens the mixed layer via plumes during violent mixing; c) baroclinic instability breaks up the mixed patch, homogenous  ater sinks and spreads, and surface  destratification completes the event (adapted from Marshall and Schott, 1999).

Schematic overview of convection phases: (a) isopycnal doming and erosion of stratification during pre-conditioning; (b) wind-driven surface heat loss deepens the mixed layer via plumes during violent mixing; c) baroclinic instability breaks up the mixed patch, homogenous ater sinks and spreads, and surface destratification completes the event (adapted from Marshall and Schott, 1999).

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