Photolysis mechanism: Difference between revisions

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== O1D reaction updated to JPL 2006 ==
Here we link to pages describing the various versions of the FAST-J and FAST-JX photolysis mechanisms used in GEOS-Chem.


As of GEOS-Chem v8-01-02, the rate constants in the "FAST-J" <tt>jv_atms.dat</tt> file have been updated from the old values:
== Photolysis mechanisms used in standard GEOS-Chem versions ==


O3_1d  180 9.000E-01 9.000E-01 3.824E-01 8.092E-02 7.650E-02      0.0      0.0
The following photolysis mechanisms have been implemented in official releases 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
O3_1d  300 9.000E-01 9.000E-01 5.273E-01 2.395E-01 7.659E-02      0.0      0.0


to these new values from JPL 2006: 
=== FAST-JX v7.0 ===


O3_1d  180 9.000E-01 9.000E-01 3.824E-01 8.092E-02 7.650E-02      0.0      0.0
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]].
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


For more information, please contact Lin Zhang (lzh@io.as.harvard.edu).
--[[User:Bmy|Bob Yantosca]] ([[User talk:Bmy|talk]]) 17:06, 16 November 2016 (UTC)


--[[User:Bmy|Bob Y.]] 11:16, 23 May 2008 (EDT)
=== FAST-J ===


== Cloud overlap options in FAST-J ==
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  It has since been replaced by [[FAST-JX v7.0 photolysis mechanism]].


GEOS-Chem now has 3 cloud overlap options in the FAST-J photolysis mechanism:
--[[User:Bmy|Bob Yantosca]] ([[User talk:Bmy|talk]]) 17:07, 16 November 2016 (UTC)


# Linear cloud overlap assumption:
== Photolysis mechanisms used in research versions of GEOS-Chem ==


Grid Box Optical depth = In-cloud optical depth * Cloud fraction
The following photolysis mechanisms have been used in non-standard research versions of GEOS-Chem:


This
=== FAST-JX v6.2 ===


# Approximate random overlap assumption:
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.


            !===========================================================
--[[User:Bmy|Bob Y.]] 11:58, 20 May 2014 (EDT)
            ! 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)
            !===========================================================

Latest revision as of 19:47, 2 January 2019

Here we link to pages describing the various versions of the FAST-J and FAST-JX photolysis mechanisms used in GEOS-Chem.

Photolysis mechanisms used in standard GEOS-Chem versions

The following photolysis mechanisms have been implemented in official releases of GEOS-Chem:

FAST-JX v7.0

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 stratospheric-tropopsheric chemistry mechanism.

--Bob Yantosca (talk) 17:06, 16 November 2016 (UTC)

FAST-J

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.

--Bob Yantosca (talk) 17:07, 16 November 2016 (UTC)

Photolysis mechanisms used in research versions of GEOS-Chem

The following photolysis mechanisms have been used in non-standard research versions of GEOS-Chem:

FAST-JX v6.2

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.

--Bob Y. 11:58, 20 May 2014 (EDT)

Retrieved from "https://wiki.seas.harvard.edu/geos-chem/index.php?title=Photolysis_mechanism&oldid=40057"