Ocean

Surface Currents

Foo Surface Currents Working Group

This group is no longer meeting.

To get involved or for more information, please email Richard Saunders (Integrated Marine Observing System) at [email protected].

The Surface Current Working Group provide input to the FOO Steering Committee on issues relating to:

  • surface current priorities that are likely to affect the capability;
  • productivity of operational oceanographic activities in Australia; and
  • to address key questions for FOO

Scope

The FOO recognizes that one of the key products of an ocean forecasting system is its estimate of the ‘surface current’, but that this term is not well defined.

The FOO recommends that users and suppliers of ocean information be very clear about the following issues:

  • Depth-averaging
  • Time-averaging

Data also includes the metadata to describe these data.

Surface Waves

Depth-Averaging

The term ‘surface current’ is variously applied to model estimates for layer thicknesses ranging from 10m to 10cm, and observed velocities at depths ranging from 12m (Surface Velocity Program drifters) to 1m (SLDMBs) or less. The problem is that near-surface shear can be significant so the FOO recommends that the term ‘surface’ be phased out in preference for a terminology that is more explicit about vertical averaging.

The FOO also notes that the ‘1m current’ is the layer-average most applicable to SAR but observations of this quantity are few, and forecasts of it are not yet available in Australia operationally (Australia’s operational ocean model has a surface layer that is 5m thick so the un-modelled shear needs to be taken into account).

Time-Averaging

Modelled and observed velocities are always an average over an interval of time – a day in the case of Australia’s operational system. But users typically require estimates at shorter intervals than this so that the effects of tides, inertial oscillations and other atmospherically-forced motions are represented.

The FOO recommends that operational forecasts be available at hourly intervals, with tides included. The problem here is whether the sub-daily variations are accurate, or merely realistic.

The FOO recommends that skill assessments be conducted separately for timescales ranging from multi-year to hours.

tructure & Membership

The Surface Current Working Group is comprised of members from all pillars of FOO.

Membership is open to:

  • any person affiliated with a FOO pillar;
  • interested in data management and data sharing;
  • and willing to contribute an appropriate level of effort towards FOO activities.

Prospective members can nominate themselves for membership by contacting the current Group Chair. Appointment of members is made at discretion of the current Chair.

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