NPZD negative concentration for no3 and all bio variables

[shailee]

hello,
i am new to roms,and i want to run coupled bio-physical model with simple NPZD module. i had tried climatological run using available data with roms as per given in user guide. I got a negative concentration of no3 (nitrate) value after few days of simultaions and its still growing with model simulating time-steps.
Can some-body find out what could be the possible reason for getting these negative concentration of nitare?

with this i'm waiting for technical solution for my case study.


With warm regards
shailee
reserch scholar

[kate]

Many advection schemes can give you the negative values. I limit NPZ tracers to be non-negative. Salt too.

[shailee]

Thanks kate,
As per previous discussion in forum TS_MPDATA can solve negative value problem but in roms agrif version 3.1.1 i could not find this type of scheme.also i triedQuasi -monotone lateral advection scheme (WENO5 ) still its negative.i'll try to limit trcers. Is there any problem in bio_nchlpzd.f ??
Any suggestions are really means a lot to me