Difference between revisions of "GEOS-Chem chemistry mechanisms"

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GEOS-Chem can also perform "specialty simulations" (aka "offline simulations").  These are simulations for species having simpler chemistry mechanisms that do not require the use of the full chemical solver.  Many of these simulations rely on oxidant fields (O3, OH) saved out from one a "full-chemistry" simulation.
 
GEOS-Chem can also perform "specialty simulations" (aka "offline simulations").  These are simulations for species having simpler chemistry mechanisms that do not require the use of the full chemical solver.  Many of these simulations rely on oxidant fields (O3, OH) saved out from one a "full-chemistry" simulation.
  
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The following table provides more information about the available specialty simulations in GEOS-Chem.  Please note that some of these simulations are out of date and will need some intervention to be brought back to the state of the science.  Contact the relevant [http://acmg.seas.harvard.edu/geos/geos_working_groups.html GEOS-Chem Working Groups] for more information.
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The following table provides links to information about the available specialty simulations in GEOS-Chem.  Please note that some of these simulations are out of date and will need some intervention to be brought back to the state of the science.  Contact the relevant [http://acmg.seas.harvard.edu/geos/geos_working_groups.html GEOS-Chem Working Groups] for more information.
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{| border=1 cellspacing=0 cellpadding=5
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|-bgcolor="#CCCCCC"
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!width="150px"|Category
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!width="300px"|Simulation
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!width="150px"|Status
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!width="250px"|Contact
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|-valign="top"
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|Aerosols
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|[[Aerosol-only simulation]]<br>(NOTE: this can be customized to include only the aerosol species you are interested in)
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|Up-to-date
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|[[Aerosols Working Group]]
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|-valign="top"
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|Carbon Gases
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|[[Tagged CO simulation]]
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|Up-to-date
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|[[Carbon Cycle Working Group]]
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|-valign="top"
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|Carbon Gases
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|[[CO2 simulation]]
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|Up-to-date
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|[[Carbon Cycle Working Group]]
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|-valign="top"
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|Radionuclides
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|[[Rn-Pb-Be simulation]]
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|Up-to-date
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|[[Transport Working Group]]
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|-valign="top"
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|Radionuclides
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|H2-HD isotope simulation
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|Needs attention
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|[[Transport Working Group]]
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|}

Revision as of 14:46, 1 October 2013

On this page, we provide an overview of the chemistry mechanisms used in GEOS-Chem.

Overview

GEOS-Chem can perform many different types of chemical simulations, including:

  • Several detailed ozone chemistry mechanisms
  • Specialty simulations for tracers with simpler chemistry, including
    • Radon-Lead-Beryllium
    • Carbon gases (CO, CO2)
    • Mercury
    • Methane
    • etc.

You may find more information about each of these mechanisms in the subsections below.

--Bob Y. 10:08, 1 October 2013 (EDT)

NOx-Ox-hydrocarbon-aerosol chemistry and variants

The NOx-Ox-hydrocarbon-aerosol (aka "full-chemistry") simulations have undergone several updates in recent GEOS-Chem versions. We provide a summary of these updates in this section.

Mechanisms in GEOS-Chem v9-01-03 and prior versions

In GEOS-Chem v9-01-03, users could select from one of four pre-defined chemistry mechanisms:

Mechanism Description Nickname Solvers
standard Full-chemistry,
fullchem
SOA
  • NOx-Ox-hydrocarbon-aerosol species
  • PLUS secondary organic aerosol species
 SOA
Dicarbonyls
  • NOx-Ox-hydrocarbon-aerosol species
  • PLUS dicarbonyl species
 Dicarbonyls
  • SMVGEAR only
isoprene
  • NOx-Ox-hydrocarbon-aerosol species
  • PLUS isoprene oxidation products
 Caltech isoprene scheme,
Paulot isoprene scheme

The bromine tracers and species were added to the standard mechanism just prior to the release of GEOS-Chem v9-01-03.

-Bob Y. 17:00, 30 September 2013 (EDT)

Mechanisms in GEOS-Chem v9-02 and later versions

Several modifications were made to the above-mentioned chemistry mechanisms in GEOS-Chem v9-02, as listed below:

Mechanism Description Nickname Solvers
standard Full-chemistry,
fullchem
SOA SOA
Dicarbonyls
  • NOx-Ox-hydrocarbon-aerosol species
  • PLUS dicarbonyl species
 Dicarbonyls
  • SMVGEAR only

Starting with v9-02, family tracers (NOx, Ox) have now been removed from all GEOS-Chem mechanisms. The individual family members (NO, NO2, O3, etc.) are now carried as individual advected tracers and chemical species. Also, the isoprene mechanism from v9-01-03 now has been folded into the standard mechanism.

--Bob Y. 09:56, 1 October 2013 (EDT)

Mechanisms in GEOS-Chem v10

We propose adding the Unified tropospheric-stratospheric Chemistry eXtension (UCX) mechanism into the release following GEOS-Chem v9-02. UCX, which was developed by Steven Barrett's group (the MIT Laboratory for Aviation and the Environment), combines the existing GEOS-Chem "standard" mechanism (based on v9-01-03) with several new stratospheric species and reactions.

Because UCX will be a major update to GEOS-Chem, we propose naming the version in which it ships to GEOS-Chem v10-01. This will make it easier to denote versions that contain UCX from versions that do not.

--Bob Y. 10:04, 1 October 2013 (EDT)

Flexchem

We also propose to add a cleaner implementation of KPP into GEOS-Chem. This implementation, which we have named Flexchem, will allow users to customize the chemical mechanism according to their research interests. Flexchem will remove the existing SMVGEAR and KPP infrastructure, and all related input files (i.e. globchem.dat, mglob.dat, etc.)

As of this writing (Oct 2013), Flexchem is still under development. We hope to have it installed in a version of GEOS-Chem sometime in 2014.

--Bob Y. 10:17, 1 October 2013 (EDT)

Specialty simulations

GEOS-Chem can also perform "specialty simulations" (aka "offline simulations"). These are simulations for species having simpler chemistry mechanisms that do not require the use of the full chemical solver. Many of these simulations rely on oxidant fields (O3, OH) saved out from one a "full-chemistry" simulation.

The following table provides links to information about the available specialty simulations in GEOS-Chem. Please note that some of these simulations are out of date and will need some intervention to be brought back to the state of the science. Contact the relevant GEOS-Chem Working Groups for more information.

Category Simulation Status Contact
Aerosols Aerosol-only simulation
(NOTE: this can be customized to include only the aerosol species you are interested in) 		Up-to-date Aerosols Working Group
Carbon Gases Tagged CO simulation Up-to-date Carbon Cycle Working Group
Carbon Gases CO2 simulation Up-to-date Carbon Cycle Working Group
Radionuclides Rn-Pb-Be simulation Up-to-date Transport Working Group
Radionuclides H2-HD isotope simulation Needs attention Transport Working Group
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