Clarification on Difference Between Surface Currents in HYCOM GLBy0.08/expt_93.0

[M M]

Hi,

I’m currently working on a project that requires model outputs related to ice (velocity, thickness, and fraction) as well as ocean current velocity for the same region.

I noticed that the ice dataset (GLBy0.08/expt_93.0_ice) provides only surface currents, so I also examined the 3D current dataset (GLBy0.08/expt_93.0_uv3z) from the same HYCOM experiment. However, I found that the surface current velocity from the ice dataset (ssu / eastward sea water velocity) differs slightly from the corresponding surface current in the uv3z dataset (water_u / Eastward Water Velocity).

Could you please clarify the reason for this discrepancy between the two variables? Any insights or guidance would be greatly appreciated.

With best regards,
Mahmud

[Alan Wallcraft]

The "ice" ocean surface velocity is averaged over the top 'thkcdw' meters of the water column:

3.0 'thkcdw' = thickness for near-surface currents in ice-ocean stress (m) 

Alan.