Br2 spatial pattern changes from v12.9.0 to v14.4.0

[hazel008]

Your name

Hansen Cao

Your affiliation

University of York

What happened? What did you expect to happen?

Hello, I found that Br2 spatial pattern changes a lot from v12.9 to v14.4.0. I am attaching some slides here to show simulated Br2 at surface level in Jul. Those plots were taken from GEOS-CHEM 1-month benchmark simulations. I wonder if anyone happen to know the causes behind these spatial changes? Thank you!
Br2_benchmark_run_12.9.0_to_14.4.0.pptx

What are the steps to reproduce the bug?

standard fullchem simulation with the default setup

Please attach any relevant configuration and log files.

standard fullchem

What GEOS-Chem version were you using?

14.4.0

What environment were you running GEOS-Chem on?

Local cluster

What compiler and version were you using?

gfortran

Will you be addressing this bug yourself?

Yes, but I will need some help

In what configuration were you running GEOS-Chem?

GCClassic

What simulation were you running?

Full chemistry

As what resolution were you running GEOS-Chem?

4x5

What meterology fields did you use?

GEOS-FP

Additional information

NO

[yantosca]

Thanks for writing @hazel008. There have been a lot of changes to the chemistry mechanism. The GCST has been keeping track of changes in a spreadsheet (read-only). You can take a look to see the evolution of the mean OH (which is a measure of how "hot" the chemistry is). This will also show you where the changes to the halogen species were added.