Sometimes, atmospheric models provide NEGATIVE relative humidities. It is highly recommended to remove such values because ROMS will immediately blow up because lwrad produces NaNs. It took me 2 days to locate the bug!
Therefore, when producing the forcing fields, I limit
(1) Qair to 0 <= Qair <=100
and also
(2) 0<=cloud<=1
(3) 0<=swrad
BTW, I am still using ROMS V3.6. Possibly, this problem was solved already in more up-to-date versions.
Happy Modeling!
Reiner