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 Co-Chairs | |
|---|---|
| Oxidants and Chemistry Working Group email list | geos-chem-oxidants [at] g.harvard.edu |
| To subscribe to email list | Either
Or
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| To unsubscribe from email list | Either
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--Bob Y. (talk) 18:29, 21 August 2015 (UTC)
Current GEOS-Chem Chemistry Projects (please add yours!)
| User Group | Description | Contact Person | Date Added |
|---|---|---|---|
| NIA / LaRC | Tropospheric ozone over East Asia: Ozonesonde observations and modeling analysis | Hongyu Liu | 5 May 2015 |
| University of York | Iodine chemistry | Tomas Sherwen | 24 June 2015 |
| University of York | Low NOx isoprene chemistry | Shani Garraway | 24 June 2015 |
| University of York | Impacts of uncertainty in chemical kinetics | Ben Newsome | 24 June 2015 |
| University of York | New spin-based formulation of ozone production | Pete Edwards | 24 June 2015 |
| University of York | New surface ozone dataset for model evaluation | Eric Sofen | 24 June 2015 |
| University of York | Spectral methodology for model evaluation | Dene Bowdalo | 24 June 2015 |
| University of York | Updates to the kinetics of Criegee chemistry based on new chamber experiments | Mat Evans | 24 June 2015 |
| University of York | Impact of ClNO2 chemistry on UK marine composition | Mat Evans | 24 June 2015 |
--Bob Y. 15:08, 25 April 2014 (EDT)
Current GEOS-Chem Chemistry Issues (please add yours!)
Fixes to correct ALK4 lumping issue
NOTE: This update is currently slated for v11-02a.
Barron Henderson wrote:
I have a lumping-related issue that I know some of you are already aware of. There is a chemical carbon source (and secondary ETO2 source).
Right now, ALK4 (via R4O2) produces 4.26 moles carbon products per reaction. The ALK4 representation can be traced back to a paper by Frederick Lurmann. That paper refers to a report that I have been unable to obtain. In fact, Frederick Lurmann no longer has a copy. When we spoke, however, he confirmed my suspicion that ALK4 is based on a 70% butane and 30% pentane mixture. Our 4.26 carbon product appears to be based on two differences (typos?) from the paper that alter the yields.
If ALK4 emissions are introduced using a 4C assumption, then ALK4 chemistry is acting as a 7% carbon source. From a ozone reactivity standpoint, this is not a major issue. First, the speciation of VOC is highly uncertain and most of the atmosphere is NOx-limited. Even so, it represents another reason to revisit our lumped species.
I have extensive notes on what I interpret as happening. To the best of my knowledge, we need to make three modifications to R4O2 + NO. The first two are to make R4O2 correctly linked to Lurmann and the third is to correctly connect the mass emissions with the molar conservation.
- Increase MO2 stoichiometry from 0.18 to 0.19
- Increase RCHO stoichiometry from 0.13 to 0.14 (or A3O2 from 0.05 to 0.06 -- it is not clear to me when this was introduced).
- Modify the carbon count (i.e. the MolecRatio field in the GEOS-Chem species database) from 4 to 4.3.
Fixes 1 and 2—which can be applied to the KPP globchem.eqn file—will make the carbon conservation consistent with Lurmann's. Right now, it looks like there were a couple changes that could have been inadvertent (i.e., 0.18 instead of 0.19). If there was a reason for these changes, I have been unable to find it.
--Bob Yantosca (talk) 20:21, 31 January 2017 (UTC)
JPL Released 18th Rate Coefficient Evaluation
NOTE: This update is currently slated for v11-02a.
JPL has released its 18th evaluation of chemical rate coefficients for atmospheric studies (Burkholder et al., 2015)." A new page (Updates in JPL Publication 15-10) is being created to compare rates between GEOS-Chem v10 and JPL Publication 15-10.
- J. B. Burkholder, S. P. Sander, J. Abbatt, J. R. Barker, R. E. Huie, C. E. Kolb, M. J. Kurylo, V. L. Orkin, D. M. Wilmouth, and P. H. Wine "Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies, Evaluation No. 18," JPL Publication 15-10, Jet Propulsion Laboratory, Pasadena, 2015 http://jpldataeval.jpl.nasa.gov.
---B. Henderson 2016-05-03 15:25 (EDT)
Working Group Tele-con on the 2nd December 2011
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)
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
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)
Acetone photolysis
This discussion has been moved to our FAST-J photolysis mechanism wiki page.
--Bob Y. 15:20, 20 May 2014 (EDT)
Issues that have been since rendered obsolete by newer code updates
NIT should be converted to molec/cm3 in calcrate.F
SMVGEAR was removed from GEOS-Chem v11-01 and higher versions. The code in calcrate.F will be replaced by the KPP master equation file.
In calcrate.F, we have:
! Nitrate effect; reduce the gamma on nitrate by a
! factor of 10 (lzh, 10/25/2011)
IF ( N == 8 ) THEN
TMP1 = State_Chm%Tracers(IX,IY,IZ,IDTSO4) +
& State_Chm%Tracers(IX,IY,IZ,IDTNIT)
TMP2 = State_Chm%tracers(IX,IY,IZ,IDTNIT)
IF ( TMP1 .GT. 0.0 ) THEN
XSTKCF = XSTKCF * ( 1.0e+0_fp - 0.9e+0_fp
& *TMP2/TMP1 )
ENDIF
ENDIF
Here NIT is added to SO4 but NIT is in different units than SO4. This unit difference can be traced to the definition of IDTRMB, which is only nonzero for species that are in the SMVGEAR mechanism. Since NIT is not a SMVGEAR species, IDTRMB = 0 for NIT and it is therefore skipped in the unit conversion from kg --> molec/cm3 in partition.F.
This issue was discovered during the implementation of FlexChem. In GEOS-Chem v11-01g and later versions, units of NIT are properly accounted for in routine HETN2O5 (found in gckpp_HetRates.F90).
--Melissa Sulprizio (talk) 20:25, 12 September 2016 (UTC)
--Bob Yantosca (talk) 20:27, 31 January 2017 (UTC)
rate of HNO4
SMVGEAR was removed from GEOS-Chem v11-01 and higher versions. The globchem.dat file is now replaced by the KPP master equation file.
Ellie Browne found a typo in the globchem.dat (GEOS-Chem 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)
--Bob Yantosca (talk) 20:29, 31 January 2017 (UTC)
near-IR photolysis of HNO4
This update was added to GEOS-Chem v8-02-04.
SMVGEAR was removed from GEOS-Chem v11-01 and higher versions. The globchem.dat file is now replaced by the KPP master equation file. Also, FAST-JX has now replaced FAST-J photolysis.
1. Since FastJX already takes this into account with cross section data at 574nm, we do not need to redo this in calcrate.f. We can therefore comment out this entire IF block:
!---------------------------------------------------------------------
! Prior to 10/27/09:
! FastJX has taken near-IR photolysis into account with
! cross section at 574nm, so we don't need to add 1e-5 anymore.
! According to Jimenez et al., "Quantum yields of OH, HO2 and
! NO3 in the UV photolysis of HO2NO2", PCCP, 2005, we also
! changed the branch ratio from 0.67(HO2)/0.33(OH) to 0.95/0.05
! This will put most weight of near-IR photolysis on HO2 channel.
! (jmao, bmy, 10/27/09)
!
!!==============================================================
!! HARDWIRE addition of 1e-5 s-1 photolysis rate to
!! HNO4 -> HO2+NO2 to account for HNO4 photolysis in near-IR --
!! see Roehl et al. 'Photodissociation of peroxynitric acid in
!! the near-IR', 2002. (amf, bmy, 1/7/02)
!!
!! Add NCS index to NKHNO4 for SMVGEAR II (gcc, bmy, 4/1/03)
!!==============================================================
!IF ( NKHNO4(NCS) > 0 ) THEN
!
! ! Put J(HNO4) in correct spot for SMVGEAR II
! PHOTVAL = NKHNO4(NCS) - NRATES(NCS)
! NKN = NKNPHOTRT(PHOTVAL,NCS)
!
! DO KLOOP=1,KTLOOP
! RRATE(KLOOP,NKN)=RRATE(KLOOP,NKN) + 1d-5
! ENDDO
!ENDIF
!---------------------------------------------------------------------
2. We need to change the branch ratio of HNO4 photolysis in ratj.d. Change these lines from:
13 HNO4 PHOTON OH NO3 0.00E+00 0.00 33.3 HO2NO2 14 HNO4 PHOTON HO2 NO2 0.00E+00 0.00 66.7 HO2NO2
to:
13 HNO4 PHOTON OH NO3 0.00E+00 0.00 5.0 HO2NO2 14 HNO4 PHOTON HO2 NO2 0.00E+00 0.00 95.0 HO2NO2
This is based on Jimenez et al. (Quantum yields of OH, HO2 and NO3 in the UV photolysis of HO2NO2, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 2005) shows that HO2 yield should be 0.95 and OH yield should be 0.05 for wavelength above 290nm.
This way all the near-IR photolysis will have most weight on HO2 channel(Stark et al., Overtone dissociation of peroxynitric acid (HO2NO2): Absorption cross sections and photolysis products, JOURNAL OF PHYSICAL CHEMISTRY A, 2008).
This update has now been added to the chemistry mechanism documentation file.
--J Mao. 11:00, 26 Oct 2009 (EDT)
--Bob Y. 16:08, 4 November 2011 (EDT)
yield of isoprene nitrates
This update was added to GEOS-Chem v8-03-02 as a post-release patch, and standardized in GEOS-Chem v9-01-01.
SMVGEAR was removed from GEOS-Chem v11-01 and higher versions. The globchem.dat file is now replaced by the KPP master equation file.
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 Yantosca (talk) 20:31, 31 January 2017 (UTC)
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.
The binary-punch format restart.cspec.YYYYMMDDhh file is slated to be replaced by a netCDF-format restart file, starting in GEOS-Chem v11-01 and higher versions. But during a transition period, you can still request binary-punch format output.
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)
--Bob Yantosca (talk) 20:33, 31 January 2017 (UTC)
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)