Initializing ridge ratio based on MYI/FYI observation

[docguibou]

I would like to initialize the ridge ratio to around .7 for MYI and .2 for FYI when initializing with CS2SMOS. (or at least to have the option to do that)
This would help tuning the meltponds without having to wait for 3 years spinup.

[tdcwilliams]

For my forecast I used .4 for MYI since it seems to stay mostly about .4 away from the coasts. I still had a one year spin-up though (and thus initialised FYI to 0). Also you should remove the dependence on concentration through the compactness parameter otherwise everything will still end up about 0.

[docguibou]

I've had a check, and it seems the ridge ratio requires ~3 years of spinup, where a MYI concentration of 100% gives you a rr of around 70%. For the FYI, it strongly depends on the season. In November/December, .1 would be more appropriate. In May/June, it is closer to .3 (second year ice seems around .4/.5, which agrees with your estimate, Tim). Of course, it depends on the tuning of the rheological parameters. I'm not sure about what you mean with the compactness parameter, but I guess Einar will understand.

[tdcwilliams]

this line should go:

M_ridge_ratio[i]=M_ridge_ratio[i]*std::exp(compaction_param*(1.-M_conc[i]));