tamoc/ambient.py z.valid_max value problem

[bhattvihang]

The problem was with tamoc/ambient.py

In order to resolve the issue with tamoc_spill in pygnome, I had to go in to tamoc/ambient.py and change z.valid_max value. It was 0 earlier. I changed it to z.valid_max=5000. I think any large number is valid as z_max is computed from CTD profile. The z.valid_max=0 creates unnecessary masked array of z that leads to error in running tamoc_spill in pygnome.