Mean OH concentration
On this page we track the evolution of the mean OH concentration in GEOS-Chem. This value is an indicator of how "hot" the chemistry is. Please also see the related topic about the methyl chloroform lifetime in GEOS-Chem.
Computation of the mean OH diagnostic
The mean OH diagnostic in GEOS-Chem is computed in diag_pl_mod.f.
Routine DO_DIAG_OH sums up the tropospheric air mass and mass-weighted OH mass after each call to the chemistry solver. The summing happens in these lines of code:
! Sum air mass term into AIR_MASS array XAIRMASS = AIRDENS(JLOOP) * VOLUME(JLOOP) AIR_MASS(I,J,L) = AIR_MASS(I,J,L) + XAIRMASS ! Sum OH mass term into OH_MASS array XOHMASS = CSPEC(JLOOP,IDOH) * XAIRMASS OH_MASS(I,J,L) = OH_MASS(I,J,L) + XOHMASS
where the arrays contain the following quantities:
JLOOP = 1-D array index for SMVGEAR I,J,L = 3-D array indices AIRDENS(JLOOP) = air density [molec/cm3] VOLUME(JLOOP) = grid box volume [cm3] AIR_MASS(I,J,L) = air mass [molec air] CSPEC(JLOOP,IDOH) = OH concentration [molec OH/cm3] OH_MASS(I,J,L) = mass-weighted OH = OH mass * air mass [molec OH/cm3 * molec air]
After the GEOS-Chem simulation finishes, the mean OH value is printed out in subroutines PRINT_MEAN_OH:
! Total Mass-weighted OH [molec OH/cm3] * [molec air] SUM_OHMASS = SUM( OH_MASS ) ! Atmospheric air mass [molec air] SUM_MASS = SUM( AIR_MASS ) ! Divide OH [molec OH/cm3 * molec air] by [molec air] and report as [1e5 molec/cm3] OHCONC = ( SUM_OHMASS / SUM_MASS ) / 1d5 ! Write value to log file WRITE( 6, '(/,a)' ) REPEAT( '=', 79 ) WRITE( 6, * ) 'ND23: Mass-Weighted OH Concentration' WRITE( 6, * ) 'Mean OH = ', OHCONC, ' [1e5 molec/cm3]' WRITE( 6, '( a)' ) REPEAT( '=', 79 )
Typical values vary between 105 - 115 molec/cm3.
--Bob Y. 15:12, 11 February 2010 (EST)
Evolution of mean OH in GEOS-Chem
Plot of mean OH evolution
Here is a plot of the mean OH concentration from several recent GEOS–Chem 1-year benchmark simulations. The mean OH is an indicator how the chemistry mechanism is performing. Typical values are 10–12 x 105 molecules cm-1.
--Bob Y. 12:41, 17 January 2014 (EST)
Mean OH in GEOS-Chem v11
The following table chronicles the evolution of the mean OH value from several different GEOS-Chem simulations. All benchmark simulations were conducted at 4 x 5 resolution unless noted otherwise.
--Bob Yantosca (talk) 18:12, 29 March 2018 (UTC)
Mean OH in GEOS-Chem v10
The following table chronicles the evolution of the mean OH value from several different GEOS-Chem simulations. All benchmark simulations were conducted at 4 x 5 resolution unless noted otherwise.
Benchmark | Met Fields & Year | Mean OH [105 molec cm-3] |
Change from prev. version [105 molec cm-3] |
Important updates in this benchmark simulation | References |
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v10-01i-Run0 | GEOS-FP 2013 | 11.125 | 0.033 (0.298%) |
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v10-01h-Run0 | GEOS-FP 2013 | 11.092 | -0.751 (-6.341%) |
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v10-01e-Run1 | GEOS-FP 2013 | 11.843 | -0.042 (-0.353%) |
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v10-01c-Run1 | GEOS-FP 2013 | 11.885 | -0.665 (-5.299%) |
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v10-01c-Run0 | GEOS-FP 2013 | 12.550 | -0.139 (-1.095%) |
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--Bob Yantosca (talk) 18:12, 29 March 2018 (UTC)
Mean OH in GEOS-Chem v9
The following table chronicles the evolution of the mean OH value from several different GEOS-Chem simulations. All benchmark simulations were conducted at 4 x 5 resolution unless noted otherwise.
--Bob Yantosca (talk) 18:12, 29 March 2018 (UTC)
Mean OH in GEOS-Chem v8
The following table chronicles the evolution of the mean OH value from several different GEOS-Chem simulations. All benchmark simulations were conducted at 4 x 5 resolution unless noted otherwise.
Benchmark | Met Fields & Year | Mean OH [105 molec cm-3] |
Change from prev. version [105 molec cm-3] |
Important updates in this benchmark simulation | References |
---|---|---|---|---|---|
v8-02-04-Run2 | GEOS-5.1.0 2005 | 11.067 | +0.019 (+0.17%) |
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v8-02-04-Run1 | GEOS-5.1.0 2005 | 11.048 | +0.598 (+5.72%) |
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v8-02-04-Run0 | GEOS-5.1.0 2005 | 10.450 | -1.362 (-11.53%) |
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v8-02-01-Run0 | GEOS-5.1.0 2005 | 11.812 | +0.713 (+6.42%) |
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v8-01-04-Run2 | GEOS-5.1.0 2005 | 11.099 | +0.805 (+7.82%) |
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v8-01-04-Run1 | GEOS-5.0.1 2005 | 10.294 | -0.395 (-3.69%) |
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v8-01-04-Run0 | GEOS-5.0.1 2005 | 10.689 | -1.351 (-11.22%) |
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v8-01-01-Run1 | GEOS-5.0.1 2005 | 12.040 | +0.034 (+0.28%) |
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v8-01-01-Run0 | GEOS-5.0.1 2005 | 12.006 | -0.141 (-1.16%) |
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--Bob Yantosca (talk) 18:11, 29 March 2018 (UTC)
Mean OH in GEOS-Chem v7
The following table chronicles the evolution of the mean OH value from several different GEOS-Chem simulations. All benchmark simulations were conducted at 4 x 5 resolution unless noted otherwise.
Benchmark | Met Fields & Year | Mean OH [105 molec cm-3] |
Change from prev. version [105 molec cm-3] |
Important updates in this benchmark simulation | References |
---|---|---|---|---|---|
v7-04-13-Run | GEOS-4 2005 | 12.147 | -0.669 (-5.22%) |
||
v7-04-12-Run2 | GEOS-4 2005 | 12.816 | +1.053 (+8.95%) |
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v7-04-12-Run1 | GEOS-4 2005 | 11.763 | -0.68 (-5.5%) |
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v7-04-02-MEGAN | GEOS-4 2001 | 12.44 | -0.11 (-0.87%) |
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v7-04-02-NOMEGAN | GEOS-4 2001 | 12.55 | +0.01 (+0.08%) |
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v7-04-02-Base | GEOS-4 2001 | 12.54 | +0.67 (+5.6%) |
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v7-02-03-Run1 | GEOS-4 2001 | 11.87 | +1.39 (+13.26%) |
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v7-02-03-Run0 | GEOS-3 2001 | 10.48 | --- |
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--Bob Yantosca (talk) 18:11, 29 March 2018 (UTC)
Additional documentation
GEOS-Chem version 8
- Differences in isoprene between v8-02-04-Run1 and v8-02-04-Run0
- Differences between MODIS LAI and AVHRR LAI
GEOS-Chem version 7
- Rynda Hudman investigated the changes in CO and O3 among benchmark simulations from v7-02-03 thru v7-04-12.
- List of differences in benchmark simulations between v7-02-03 and v7-04-02.
- List of differences in benchmark simulations between v7-04-02 and v7-04-12.
- Changes in anthropogenic NOx and CO from 1-yr benchmarks with versions v7-02-03 and v7-02-04
- Jennifer Logan looked at some of the differences between GEOS-3 and GEOS-4 in 1-year benchmark simulations.
--Bob Y. 09:32, 23 February 2010 (EST)