FORUM RESEND QUESTION

[academic yuca]

What is the difference between SSH and Steric SSH from ESPC-D-V02 data? Forcing, tidal forcing, and non-tidal forcing? Pls detail it to me

Thank you

[Alan Wallcraft]

The Steric SSH is the SSH associated with changes in water column density, so the remainder, non-Steric SSH, is the SSH associated with changes in water column mass. When running an ocean model with tides, Steric SSH does not include the external tide (of order 1 m) or atmospheric pressure anomaly but it does  include the effects if the internal tides (of order a few cm).  So it "filters" the external tides and therefore largely looks like SSH from a run without tides.

See:

Zaron, E. and Ray, R. (2023). Clarifying the Distinction between Steric and Baroclinic Sea Surface Height. Journal of Physical Oceanography 53(11) pp. 2591-2596.

which points out that using Steric SSH to quantify internal tides gives a 10% to 20% error over the correct Baroclinic SSH.

Alan.

[academic yuca]

1. Does the SSH in this dataset represent the total surface elevation, including both tidal forcing and non-tidal factors (such as wind stress, atmospheric pressure/inverse barometer, and density-driven changes)?

2. Regarding the Steric SSH (SSSH), is it strictly limited to the density-driven component (T and S), and does it inherently exclude all tidal and atmospheric pressure signals?

[Alan Wallcraft]

1. Yes, SSH is total surface elevation, including tidal and non-tidal factors

2. Yes, Steric SSH excludes the external tide (of order 1 m) and atmospheric pressure anomaly forcing but includes the effects of the internal tides (of order a few cm).

Alan.