Large unphysical negative values (q, CO₂, O₃) after assimilating with DART and CESM – looking for possible causes and solutions

[jurymark]

Dear all,

I am using DART to perform Ensemble Adjustment Kalman Filter (EAKF) assimilation with CESM2. After the assimilation, the analysis fields and the updated restart files contain widespread unphysical negative values, mainly for specific humidity (q), CO₂, and ozone (O₃). Temperature (T) and wind fields (U/V) appear normal.

fwdart.cam_0001.h3.2014-01-01-03600.log
Here is the report on querying abnormal values, as well as the two stages of input.nml0->input.nml.
input.nml.txt
input.nml0.txt
and
obs_def_simple.f90.txt

[hkershaw-brown]

Hi @jurymark can you send a short email to dart@ucar.du introducing yourself and your project.
Cheers,
Helen

[hkershaw-brown]

moved to support, using_chemistry = .true. for cam-chem