Pliocene forcing of DSW model

[dkhutch]

During the workshop, we discussed in a meeting with Katrin and Laurie possibilities for forcing the OM2-01 model with Pliocene boundary conditions. During this conversation we thought it might be a good idea to use outputs from a Pliocene coupled model to see if these could force DSW formation, in the same way that the CM2 wind anomalies have been able to do. There are two basic approaches we could take:

1. Use PlioMIP monthly fields, and take anomalies on top of the JRA high-frequency forcing (like we did for the CM2 winds)
2. Use output from a GFDL CM2.1 simulation, to output the required 3 or 6 hourly winds directly, instead of the anomaly approach.

I happen to have an early Pliocene simulation (I did it for Udara Amarathunga) which we could use for this. I more or less followed the PlioMIP protocols for that, i.e. altered Antarctic and Greenland ice sheets and used CO2 of 415 ppm. The atmosphere resolution is 2 x 2.5 deg (lat x lon). Can output a year of that for instance, at high frequency.

[wghuneke]

I've a script for option 1.

Would the simulation be of interest for you to analyse further or mostly to understand the sensitivity of OM2-01 DSW formation to winds? Is the geometry in the Pliocene run the same as present day?

[dkhutch]

I think the motivation is to understand whether the warmer world and reduced ice sheet would affect DSW formation. There was also some discussion of applying a simple temperature anomaly like +3 deg SST.

The advantage of using full output from GFDL CM2.1 is that ice sheet, sea ice, climatologies etc are all physically consistent with each other. Geography (as in plate tectonics) is broadly the same, but there are some tweaks to the land sea mask all over the world because of sea level adjustments.

[dkhutch]

Just discussed with Wilton - I will make some preliminary figures of monthly outputs of wind, to do a comparison with the CM2 + JRA example. I will also make a couple of figures to show the Pliocene ice extent, and the P-E over the Antarctic region. I gather we are not ready to set up a Pliocene-forced experiment at this point, but some prelim figures might be useful.