Chemistry Working Group
Oxidants and Chemistry Working Group
All users interested in the GEOS-Chem chemistry scheme and associated processes (photolysis, heterogeneous, deposition) are encouraged to subscribe to the chemistry email list (click on the link in the contact information section below).
Contact information
| Oxidants and Chemistry Working Group Chair | Mat Evans |
| Oxidants and Chemistry Working Group email list | geos-chem-oxidants@seas.harvard.edu |
| To subscribe to email list | Send email to geos-chem-oxidants-join@seas.harvard.edu |
| To unsubscribe from email list | Send email to geos-chem-oxidants-leave@seas.harvard.edu |
Current GEOS-Chem Chemistry Projects (please add yours!)
| User Group | Description | Contact Person | Date Added |
|---|---|---|---|
| Caltech/Harvard | Examining the effects of isoprene nitrates and epoxide on tropical ozone and OH using SHADOZ and OMI measurements | Fabien Paulot Jingqiu Mao |
April 28, 2009 |
| Caltech/Harvard | Examining the HCHO yield, OH recycling and ozone production with INTEX-A observations from new isoprene chemistry | Jingqiu Mao Fabien Paulot |
April 28, 2009 |
| NIA / LaRC | Tropospheric ozone over East Asia: Ozonesonde observations and modeling analysis | Yiqiang Zhang Hongyu Liu |
June 29, 2010 |
| U. Wollongong | Tropospheric ozone precursors over Australasia: Using GEOS-Chem to interpret FTIR measurements of CO, NO2 and HCHO | Rebecca Buchholz | May 19, 2011 |
Current GEOS-Chem Chemistry Issues (please add yours!)
Isoprene chemistry
I've created a page with some of the recent literature on isoprene chemistry. Please add more papers as they come along! ( MJE Leeds)
rate of HNO4
Ellie Browne found a typo in the globchem.dat (v8-02-01 and beyond)
A 73 9.52E-05 3.2E+00 -10900 1 P 0.60 0. 0.
1.38E+15 1.4E+00 -10900 0 0.00 0. 0.
HNO4 + M
=1.000HO2 +1.000NO2 + +
This should be corrected as:
A 73 9.52E-05 3.4E+00 -10900 1 P 0.60 0. 0.
1.38E+15 1.1E+00 -10900 0 0.00 0. 0.
HNO4 + M
=1.000HO2 +1.000NO2 + +
The difference is within 2%.
--J Mao. 19:04, 30 Aug 2010 (EDT)
HO2 + CH2O
Scheme does not contain the HO2 + CH2O --> Adduct reaction (MJE Leeds)
Hermans, I., et al. (2005), Kinetics of alpha-hydroxy-alkylperoxyl radicals in oxidation processes. HO2 center dot-initiated oxidation of ketones/aldehydes near the tropopause, Journal of Physical Chemistry A, 109(19), 4303-4311.
According to this paper, this reaction is significant when Temperature is below 220K.
--J Mao. 15:00, 10 Aug 2009 (EDT)
Previous issues that have now been resolved
This update was added to GEOS-Chem v8-03-02 as a post-release patch, and standardized in GEOS-Chem v9-01-01.
yield of isoprene nitrates
Fabien Paulot found a problem in current chemistry scheme. In GEOS-Chem v8-02-01 and beyond, isoprene nitrates are produced twice: one through channel A and one through 10% loss in channel B. This makes the loss of NOx larger than it should be (18.7% vs. 10%) and also reduces the yield of MVK/MACR/CH2O by about 13%.
A 453 2.70E-12 0.0E+00 350 1 B 0.00 0. 0.
5.00E+00 0.0E+00 0 0 0.00 0. 0.
RIO2 + NO
=0.900NO2 +0.900HO2 +0.340IALD +0.340MVK
+0.220MACR +0.560CH2O + +
A 453 2.70E-12 0.0E+00 350 1 A 0.00 0. 0.
5.00E+00 0.0E+00 0 0 0.00 0. 0.
RIO2 + NO
=1.000HNO3 + + +
So it should be corrected as (no channel A):
A 453 2.70E-12 0.0E+00 350 0 0 0.00 0. 0.
RIO2 + NO
=0.900NO2 +0.900HO2 +0.340IALD +0.340MVK
+0.220MACR +0.560CH2O + +
D 453 2.70E-12 0.0E+00 350 1 A 0.00 0. 0.
5.00E+00 0.0E+00 0 0 0.00 0. 0.
RIO2 + NO
=1.000HNO3 + + +
--J Mao. 18:04, 30 Aug 2010 (EDT)
--Bob Y. 16:05, 4 November 2011 (EDT)
Potential issue with reading restart.cspec file
This update was tested in the 1-month benchmark simulation v9-01-02c and approved on 21 Jul 2011.
Jingqiu Mao discovered a mis-indexing problem when using the restart.cspec.YYYYMMDDhh file. Please see this wiki post for more information.
--Bob Y. 16:02, 4 November 2011 (EDT)
Centralizing chemistry time step
This update was tested in the 1-month benchmark simulation v9-01-02q and approved on 18 Oct 2011.
Please see the full discussion on the Centralized chemistry time step wiki page.
--Bob Y. 16:01, 4 November 2011 (EDT)
Documentation
- Updated chemical reactions that will be used in GEOS-Chem v8-02-04 and higher.
- Updated chemical reactions now used in GEOS-Chem v8-02-01 through GEOS-Chem v8-02-03.
- All typos have now been corrected in the present file.
- Format of FAST-J input file jv_spec.dat
--Bob Y. 15:41, 27 October 2009 (EDT)