I'll try again later but at present that link (ftp) isn't working for me. Nonetheless, thanks for pointing me to the temperature dependence of ice albedo, this is designed to simulate melt ponds, hence if the ice surface is greater than the melting point of ice, albedo lowers as melt ponds form. However I can only back up what Crandles shows using the graph - I can dig out the reference for that if needs be.
Now I think about it, isn't pond formation a major player in the albedo difference between MYI and FYI? FYI tends to be flatter so more prone to melt pond formation. How much of the albedo difference is due to melt ponds, and how much due to dielectric constant differences between MYI and FYI?
As ice thickness can be seen as a proxy for age, thickness plays a major role in ice temperature, and that affects which albedo is chosen, I think I was arguably wrong to say PIOMAS doesn't model albedo changes with ice age. It is possible to view the melt pond formation parameterisation as also introducing an ice albedo effect that is indirectly affected by (implicit) ice age.
Doesn't help with the spring melt anomaly, as most of this is happening while NCEP/NCAR temperatures are below zero. I still think that anomaly is due to simple ice thickness and that thinner ice thins more over the season than thicker (see below).
I can do so, but before I do here's why I've not done so earlier.
As part of my trying to get to grips with the spring melt anomaly in PIOMAS I've done scatter plots of thinning through the season as a function of initial thickness.http://farm9.staticflickr.com/8263/8606025700_a494abf6b7_o.gif
EDIT - animated gif corrected.
I decided not to proceed with average thinning as the spread of thinning for a set initial thickness (under about 2.5m) means an average seems to me to be pretty meaningless. The graph I presented above is more meaningful because it's just looking at what grid cells 'bottom out' to zero.
I had been pondering doing some form of pdf of melt thickness based on initial thickness bands.