New Equation of State
In an attempt to figure out what's going on around Tmd in the model, especially after the onset of summer stratification, I've recoded the nonlinear equation of state in rho_eos.F (and added constants to mod_eoscoef.F).
I've used the formulation of Chen and Millero (1986) which is a set of formulae derived specifically for fresh water (i.e. S<0.6). So far the model seems to be behaving just fine- I'll know more in a few hours once it's past the stage where it undergoes the spring/summer overturn.