Changes to ASC and coastal current strength

[hrsdawson]

Thought it would be good to check changes in ASC and coastal current strength across the simulations. Figures show differences in speed from year 7 of the Basal - Control (left), Basal+Iceberg - Basal (middle) and Basal+Iceberg - Control (right).

The Basal and Iceberg contributions somewhat oppose each other. The Basal simulation generally strengthens the ASC except at depth (>2000m) downstream of the Ross Sea while the Basal + Iceberg simulation somewhat weakens the ASC . The net effect (right) is a surface strengthening of the ASC and coastal current (particularly the coastal current in West Antarctica) and a weakening of the ASC at depth downstream of the Ross Sea and Prydz Bay bottom water formation sites. In the Weddell Sea, the ASC strengthens slightly at depth. I think this is consistent with the bottom age changes we're seeing (#29). @adele157 suggested looking at density transects to help understand the coastal current changes (to be plotted).

[adele-morrison]

@hrsdawson just noticed that these figures use the old simulations. Do you think you could update with the new simulations?

[hrsdawson]

Updated figures using Year 10 monthly velocities. We get a reduction in ASC surface speed (0-200m) in the two experiments compared to the control. Reduction is stronger in the ICB gade simulation.

At mid depth (400-1000m) we get a similar weakening except in the SW Weddell Sea, and parts of the Ross Sea where we get a strengthening along the slope in the ICB gade simulation.

At depths > 2000m the ASC strengthens from the Ross around to East Antarctica and in the SW Weddell Sea (not in the Basal Gade simulation). I think this is consistent with the increase in cross slope transport of DSW particularly in the ICB gade run #65.

[hrsdawson]

Updated figure which includes the new third simulation (Basal No Gade and No ICB). The two simulations with $T{basal}$ on the Gade line result in a weakening of upper ocean ASC strength along East Antarctica and the Weddell Sea. The third (basal meltwater at depth but using $T{insitu}$) results in a slight ASC strengthening and a strengthening of the coastal current in West Antarctica.