Sulfate aerosols

Updated THNO3.geos4.4x5 file

Lyatt Jaegle (jaegle@atmos.washington.edu) wrote:

I was trying to run GEOS-Chem (v8-01-03) in the offline aerosol mode with GEOS-4 met fields and ran into a problem: it seems that the offline file GEOS_4x5/sulfate_sim_200508/offline/THNO3.geos4.4x5 is in units of ppbv instead of v/v as expected in routine GET_HNO3_UGM3. This leads to issues in RPMARES which thinks that HNO3 is very large. I checked all the other files, and they are in v/v, as expected.

Bob Yantosca (yantosca@seas.harvard.edu) wrote:

Thanks Lyatt. I've downloaded the file and updated the README in the GEOS_4x5/sulfate_sim_200508/offline directory.

--Bob Y. 14:19, 24 April 2009 (EDT)

Fix for mass balance of HNO3 and NIT

Becky Alexander (beckya@atmos.washington.edu) wrote:

We need to make a change in sulfate_mod in order to have mass balance for HNO3 and NIT. Duncan Fairlie noticed the bug. There is a simple change:

In routine SEASALT_CHEM in sulfate_mod.f: In order to have mass balance, you need to change:

   !HNO3 lost [eq/timestep] converted back to [v/v/timestep]
   HNO3_ss = TITR_HNO3 * 0.063 * TCVV(IDTHNO3)/AD(I,J,L)

to:

   !HNO3 lost [eq/timestep] converted back to [v/v/timestep]
   HNO3_ss = HNO3_SSC * 0.063 * TCVV(IDTHNO3)/AD(I,J,L)

In my original code where I added isorropia and the new tracers, NITs and SO4s, the line above:

   !HNO3 lost [eq/timestep] converted back to [v/v/timestep]
   HNO3_ss = TITR_HNO3 * 0.063 * TCVV(IDTHNO3)/AD(I,J,L)

is appropriate as long as you also have PNIT (analogous to PNITs). PNIT is in my original code where I did all my mass balance testing. PNIT got dropped when going to the standard version. I don't recall dropping this, but my guess is that I decided it was redundant to have it when isorropia would just repartition HNO3 and NIT anyway according to thermodynamic equilibrium. But when dropping PNIT, you have to change TITR_HNO3 to HNO3_SSC in the above equation in order to achieve mass balance.

NOTE: This fix is slated for inclusion in GEOS-Chem v8-01-02.

--Bob Y. 09:32, 30 July 2008 (EDT)