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| − | This page describes some of the updates to the FAST-J photolysis mechanism, as is currently implemented in GEOS-Chem.
| + | Here we link to pages describing the various versions of the FAST-J and FAST-JX photolysis mechanisms used in GEOS-Chem. |
| | | | |
| − | == Input files for FAST-J == | + | == Photolysis mechanisms used in standard GEOS-Chem versions == |
| | | | |
| − | The following input files are required for the FAST-J photolysis mechanism: | + | The following photolysis mechanisms have been implemented in official releases of GEOS-Chem: |
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| − | ;[http://www.as.harvard.edu/ctm/geos/doc/man/chapter_5.html#5.4.1 ratj.d]: This file is where you specify each of the FAST-J photolysis species. Each species is mapped to a corresponding entry of the GEOS-Chem chemical mechanism.
| + | === FAST-JX v7.0 === |
| − | ;[http://www.as.harvard.edu/ctm/geos/doc/man/chapter_5.html#5.4.2 jv_atms.dat]: This file specifies the reference O3 climatology for FAST-J. NOTE: GEOS-Chem will overwrite this reference climatology with TOMS/SBUV data for those months and locations where such data exists.
| + | |
| − | ;[http://www.as.harvard.edu/ctm/geos/doc/man/chapter_5.html#5.4.3 jv_spec.dat]: This file is where the various quantum yields and aerosol cross-sections are specified.
| + | |
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| − | == O1D reaction updated to JPL 2006 ==
| + | The [[FAST-JX v7.0 photolysis mechanism]] is the newest version of the FAST-J software. It was incorporated into [[GEOS-Chem v10-01]] by Sebastian Eastham (MIT) and the [[GEOS-Chem Support Team]], along with the [[UCX chemistry mechanism|UCX stratospheric-tropopsheric chemistry mechanism]]. |
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| − | As of GEOS-Chem v8-01-02, the rate constants in the "FAST-J" [http://www.as.harvard.edu/ctm/geos/doc/man/chapter_5.html#5.4.2 jv_atms.dat file] have been updated by Lin Zhang.
| + | --[[User:Bmy|Bob Yantosca]] ([[User talk:Bmy|talk]]) 17:06, 16 November 2016 (UTC) |
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| − | These were the old values:
| + | === FAST-J === |
| | | | |
| − | O3_1d 180 9.000E-01 9.000E-01 3.824E-01 8.092E-02 7.650E-02 0.0 0.0
| + | The [[FAST-J photolysis mechanism]] was used in GEOS-Chem versions prior to [[GEOS-Chem v10-01]]. It has since been replaced by [[FAST-JX v7.0 photolysis mechanism]]. |
| − | O3_1d 260 9.000E-01 9.000E-01 4.531E-01 1.438E-01 7.654E-02 0.0 0.0
| + | |
| − | O3_1d 300 9.000E-01 9.000E-01 5.273E-01 2.395E-01 7.659E-02 0.0 0.0 | + | |
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| − | which are now replaced by the new values from JPL 2006:
| + | --[[User:Bmy|Bob Yantosca]] ([[User talk:Bmy|talk]]) 17:07, 16 November 2016 (UTC) |
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| − | O3_1d 180 9.000E-01 9.000E-01 3.824E-01 8.092E-02 7.650E-02 0.0 0.0
| + | == Photolysis mechanisms used in research versions of GEOS-Chem == |
| − | O3_1d 260 9.000E-01 9.000E-01 4.531E-01 1.438E-01 7.654E-02 0.0 0.0
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| − | O3_1d 300 9.000E-01 9.000E-01 5.273E-01 2.395E-01 7.659E-02 0.0 0.0
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| − | For more information, please contact Lin Zhang (lzh@io.as.harvard.edu).
| + | The following photolysis mechanisms have been used in non-standard research versions of GEOS-Chem: |
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| − | --[[User:Bmy|Bob Y.]] 11:16, 23 May 2008 (EDT) | + | === FAST-JX v6.2 === |
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| − | == Cloud overlap options in FAST-J ==
| + | The [[FAST-JX v6.2 photolysis mechanism]] was implemented into several research versions of GEOS-Chem by Jingqiu Mao (Princeton). But this version of FAST-J was never incorporated into the standard GEOS-Chem model. |
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| − | GEOS-Chem now has 3 cloud overlap options in the FAST-J photolysis mechanism:
| + | --[[User:Bmy|Bob Y.]] 11:58, 20 May 2014 (EDT) |
| − | | + | |
| − | # Linear cloud overlap assumption:
| + | |
| − | | + | |
| − | Grid Box Optical depth = In-cloud optical depth * Cloud fraction
| + | |
| − | | + | |
| − | This
| + | |
| − | | + | |
| − | # Approximate random overlap assumption:
| + | |
| − | | + | |
| − | !===========================================================
| + | |
| − | ! CLOUD OVERLAP : LINEAR ASSUMPTION
| + | |
| − | ! Directly use OPTDEPTH = TAUCLD * CLDTOT
| + | |
| − | !
| + | |
| − | ! NOTE: Use this option if you want to compare to results
| + | |
| − | ! from GEOS-Chem v7-04-12 and prior versions.
| + | |
| − | !===========================================================
| + | |
| − | IF ( OVERLAP == 1 ) then
| + | |
| − | | + | |
| − | ! Call FAST-J routines to compute J-values
| + | |
| − | CALL PHOTOJ( NLON, NLAT, YLAT, DAY_OF_YR,
| + | |
| − | & MONTH, DAY, CSZA, TEMP,
| + | |
| − | & SFCA, OPTD, OPTDUST, OPTAER )
| + | |
| − | | + | |
| − | !===========================================================
| + | |
| − | ! CLOUD OVERLAP : APPROXIMATE RANDOM OVERLAP
| + | |
| − | ! Use OPTDEPTH = TAUCLD * CLDTOT**1.5
| + | |
| − | !===========================================================
| + | |
| − | ELSE IF ( OVERLAP == 2 ) THEN
| + | |
| − | | + | |
| − | ! Column cloud fraction (not less than zero)
| + | |
| − | CLDF1D = CLDF(1:LLPAR,NLON,NLAT)
| + | |
| − | WHERE ( CLDF1D < 0d0 ) CLDF1D = 0d0
| + | |
| − |
| + | |
| − | ! Adjust optical depth
| + | |
| − | OPTD = OPTD * SQRT( CLDF1D )
| + | |
| − | | + | |
| − | ! Call FAST-J routines to compute J-values
| + | |
| − | CALL PHOTOJ( NLON, NLAT, YLAT, DAY_OF_YR,
| + | |
| − | & MONTH, DAY, CSZA, TEMP,
| + | |
| − | & SFCA, OPTD, OPTDUST, OPTAER )
| + | |
| − | | + | |
| − | !===========================================================
| + | |
| − | ! CLOUD OVERLAP : MAXIMUM RANDOM OVERLAP
| + | |
| − | !
| + | |
| − | ! The Maximum-Random Overlap (MRAN) scheme assumes that
| + | |
| − | ! clouds in adjacent layers are maximally overlapped to
| + | |
| − | ! form a cloud block and that blocks of clouds separated by
| + | |
| − | ! clear layers are randomly overlapped. A vertical profile
| + | |
| − | ! of fractional cloudiness is converted into a series of
| + | |
| − | ! column configurations with corresponding fractions
| + | |
| − | ! (see Liu et al., JGR 2006; hyl,3/3/04).
| + | |
| − | !
| + | |
| − | ! For more details about cloud overlap assumptions and
| + | |
| − | ! their effect on photolysis frequencies and key oxidants
| + | |
| − | ! in the troposphere, refer to the following articles:
| + | |
| − | !
| + | |
| − | ! (1) Liu, H., et al., Radiative effect of clouds on
| + | |
| − | ! tropospheric chemistry in a global three-dimensional
| + | |
| − | ! chemical transport model, J. Geophys. Res., vol.111,
| + | |
| − | ! D20303, doi:10.1029/2005JD006403, 2006.
| + | |
| − | ! (2) Tie, X., et al., Effect of clouds on photolysis and
| + | |
| − | ! oxidants in the troposphere, J. Geophys. Res.,
| + | |
| − | ! 108(D20), 4642, doi:10.1029/2003JD003659, 2003.
| + | |
| − | ! (3) Feng, Y., et al., Effects of cloud overlap in
| + | |
| − | ! photochemical models, J. Geophys. Res., 109,
| + | |
| − | ! D04310, doi:10.1029/2003JD004040, 2004.
| + | |
| − | ! (4) Stubenrauch, C.J., et al., Implementation of subgrid
| + | |
| − | ! cloud vertical structure inside a GCM and its effect
| + | |
| − | ! on the radiation budget, J. Clim., 10, 273-287, 1997.
| + | |
| − | !-----------------------------------------------------------
| + | |
| − | ! MMRAN needs IN-CLOUD optical depth (ODNEW) as input
| + | |
| − | ! Use cloud fraction, instead of OPTD, to form cloud blocks
| + | |
| − | ! (hyl,06/19/04)
| + | |
| − | !===========================================================
| + | |
Here we link to pages describing the various versions of the FAST-J and FAST-JX photolysis mechanisms used in GEOS-Chem.
The following photolysis mechanisms have been implemented in official releases of GEOS-Chem:
The following photolysis mechanisms have been used in non-standard research versions of GEOS-Chem:
