Difference between revisions of "MEGAN biogenic emissions"

Revision as of 20:37, 25 February 2015

This page describes the implementations of the MEGAN (Model of Emissions of Gases and Aerosols from Nature) biogenic emissions in GEOS-Chem.

Overview

GEOS-Chem has used three versions of the MEGAN biogenic emissions. These are now all described on separate wiki pages.

MEGAN v2.0 biogenic emissions

The MEGAN v2.0 biogenic emissions are now obsolete. They were used in GEOS-Chem v8-02-03 and prior versions.

--Bob Y. 15:32, 25 February 2015 (EST)

MEGAN v2.1 biogenic emissions

The MEGAN v2.1 biogenic emissions were used in GEOS-Chem v8-02-04 through GEOS-Chem v9-02. They were retired with the advent of the HEMCO emissions component in GEOS-Chem v10-01.

--Bob Y. 15:32, 25 February 2015 (EST)

MEGAN v2.1 plus Guenther 2012 biogenic emissions

GEOS-Chem v10-01 and newer versions now use the MEGAN 2.1 biogenic emissions with updates from Guenther (2012); These are implemented throImplemented via the HEMCO emissions component.

--Bob Y. 15:32, 25 February 2015 (EST)

Technical notes in MEGAN 2.1

AEF_OVOC is not currently used

Jintai Lin wrote:

For global simulations, at approximately line 1863 of megan_mod.F, the file name

         !---------------------------------------------
         ! Read in other VOC Annual Emission Factors
         !---------------------------------------------

         ! 1x1 file name
         FILENAME = TRIM( DATA_DIR_1x1 ) //
        &           'MEGAN_200510/MEGAN_AEF_MTP.geos.1x1' 

should probably be

         ! 1x1 file name
         FILENAME = TRIM( DATA_DIR_1x1 ) //
        &           'MEGAN_200510/MEGAN_AEF_OVC.geos.1x1' 

with respect to emissions of other VOCs.

Dylan Millet wrote:

The other VOC emissions are not currently used. Those routines I think are mainly there as a placeholder for adding things in the future. So it doesn't matter if MEGAN_AEF_MTP is read in to AEF_OVOC, since AEF_OVOC is not used. As far as I know the file MEGAN_AEF_OVC.geos.1x1 doesn't actually exist.

--Bob Y. 13:40, 18 November 2011 (EST)

Nested simulations use wrong AEF's

We have corrected this in GEOS-Chem v9-01-02.

Jintai Lin wrote:

For nested simulations, the subroutine GET_AEF_05x0666 is not properly updated to reflect the megan 2.1 emissions.

Lin Zhang wrote:

I want to bring up an error in the MEGAN biogenic emissions with the nested model in the latest versions (eg. v9-01-01). The MEGAN emissions have been updated from MEGAN 2.0 to MEGAN 2.1 since v8-02-04 in the standard model with 4x5 or 2x2.5 resolution, however, they are not fully implemented in the nested model. The nested model for all regions still uses some old annual emission factors (as we can see in the module megan_mod.f, subroutine GET_AEF vs. GET_AEF_05x0666). This error would cause biogenic isoprene emissions (with MEGAN 2.1) over the US a factor of two higher in the nested NA model than that in the 2x2.5 model. It can also affect the CH and EU nested models.

A quick fix can be implemented by changing megan_mod.f, subroutine INIT_MEGAN from:

   #if   defined ( GRID05x0666)
         CALL GET_AEF_05x0666
   #else
         CALL GET_AEF
   #endif

to

   CALL GET_AEF

In this case, the model would read the annual emission factors at 1x1 resolution and then regrid to the underlying resolution.

--Bob Y. 12:55, 22 November 2011 (EST)

New Update Required in MEGAN algorithm

Chris Chan Miller found that the isoprene emissions in MEGAN do not capture the diurnal variability of isoprene observed in the Michigan state forest. This is because the meteorological variables input to GEOS-Chem (temperature and photosynthetically active radiation) are not interpolated between the 3-h average surface data read in to megan_mod.f. This can be fixed by including a CALL INTERP statement in main.f for I-3 met fields. Chris is working on updating this in his working code and will send necessary updates to Bob to be included in the standard code.

--Emarais 16:32, 4 April 2012 (EDT)

Update to MEGAN2.1 (Guenther et al., 2012)

Please see this file that describes an available update to MEGAN2.1 in GEOS-Chem. The update applies emission algorithm updates according to Guenther et al. (Geosci. Model Dev., 5, 1471–1492, 2012), enables computation of emissions for more compounds, uses CLM4 plant functional type distributions, facilitates computing emissions with different/dynamic land cover schemes, and streamlines the code.

Please contact Dylan Millet to obtain the code or with any questions.

Documentation:

• Readme

• Comparison between previous and updated BVOC emissions for standard tracers (year-2006):
  • 2x2.5
  • 4x5

• Comparison between previous and updated BVOC emissions for standard tracers (nested NA, year-2011):
  • 0.5x0.67

• Updated emissions for all BVOCs, including non-standard tracers:
  • 2x25

• Monthly CO comparison for previous and updated MEGAN implementation (year-2006; 4x5 resolution):
  • 4x5

--Dbm 14:18, 22 January 2013 (EST)

CO2 direct effect on isoprene emissions

This update is slated for inclusion in GEOS-Chem v10-01 or later

Amos Tai developed code updates to include CO2 inhibition of isoprene emissions in MEGAN.

The reference for this work is:

Tai, A.P.K., L.J. Mickley, C.L. Heald, S. Wu, Effect of CO2 inhibition on biogenic isoprene emission: Implications for air quality under 2000-to-2050 changes in climate, vegetation, and land use, Geophys. Res. Let., 40, 3479-3483, 2013. [pdf]

--Melissa Sulprizio 15:45, 23 January 2014 (EST)

Previous issues that have been resolved

Bug in MEGAN emissions when running with MERRA or GEOS-FP

NOTE: This issue was resolved in 1-month benchmark simulation v9-02e (07 Jan 2013).

Tzung-May Fu wrote:

I wanted to report a small but important bug in the MEGAN emissions when running with MERRA and GEOS-FP. In subroutine READ_MET_FIELDS (in GeosCore/main.F, the MEGAN subroutine UPDATE_T_DAY was never called for MERRA or GEOS-FP, except when reading the 10-day period preceeding the simulation start date. The call line was commented out in MERRA, and missing in GEOS-FP. This can lead to a 10% error in the biogenic emissions (particular isoprene) when a simulation is run a month at a time. However, say you start your simulation in January, you would still be using the same temperature in July! This can lead to a 80% underestimate of the biogenic emissions. This bug is present in v911, v912, v913 and the v92 code that Melissa sent me.

GeosCore/main.F, in routine READ_MET_FIELDS:

        !%%% NEED TO UPDATE FOR MERRA %%%
        ! Update daily mean temperature archive for MEGAN biogenics
! (tmf, 1/4/2012) This should be turned on!
        IF ( LMEGAN ) CALL UPDATE_T_DAY

--Melissa Payer 11:07, 4 January 2013 (EST)
--Bob Y. 13:49, 20 August 2013 (EDT)

Unresolved issues

None at this time.

References

1. Barkley, M., Description of MEGAN biogenic VOC emissions in GEOS-Chem, 2010. PDF
2. Buermann, W., Wang, Y.J., Dong, J.R., Zhou, L.M., Zeng, X.B., Dickinson, R.E., Potter, C.S., and Myneni, R.B.: Analysis of a multiyear global vegetation leaf area index data set, J. Geophys. Res., 107, 4646, doi:10.1029/2001JD000975, 2002.
3. Guenther, A., Baugh, B., Brasseur, G., Greenberg, J., Harley, P., Klinger, L., Serca, D., and Vierling, L.: Isoprene emission estimates and uncertainties for the Central African EXPRESSO study domain, J. Geophys. Res., 104, 30625-30639, 1999.
4. Guenther, A., Karl, T., Harley, P., Wiedinmyer, C., Palmer, P.I., and Geron, C.: Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature), Atmos. Chem. Phys., 6, 3181-3210, 2006.
5. Guenther, A., and C. Wiedinmyer, User's guide to the Model of Emissions of Gases and Aerosols from Nature (MEGAN), Version 2.01, 2007.
6. Guenther, A. B., Jiang, X., Heald, C. L., Sakulyanontvittaya, T., Duhl, T., Emmons, L. K., and Wang, X.: The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1): an extended and updated framework for modeling biogenic emissions, Geosci. Model Dev., 5, 1471-1492, doi:10.5194/gmd-5-1471-2012, 2012.
7. Millet, D.B., Jacob, D.J., Boersma, K.F., Fu, T.M., Kurosu, T.P., Chance, K., Heald, C.L., and Guenther, A.: Spatial distribution of isoprene emissions from North America derived from formaldehyde column measurements by the OMI satellite sensor, J. Geophys. Res., 113, D02307, doi:10.1029/2007JD008950, 2008. PDF
8. Mueller, J.-F., et al. Global isoprene emissions estimated using MEGAN, ECMWF analyses and a detailed canopy environment model, Atmos. Chem. Phys., 8, 1329-1341, 2008.
9. Myneni, R. B., et al., Large seasonal swings in leaf area of Amazon rainforests, Proceedings of the National Academy of Sciences, 104(12), 4820{4823, doi:10.1073/pnas.0611338104, 2007.
10. Palmer, P.I., Abbot, D.S., Fu, T.M., Jacob, D.J., Chance, K., Kurosu, T.P., Guenther, A., Wiedinmyer, C., Stanton, J.C., Pilling, M.J., Pressley, S.N., Lamb, B., and Sumner, A.L.: Quantifying the seasonal and interannual variability of North American isoprene emissions using satellite observations of the formaldehyde column, J. Geophys. Res., 111, D12315, doi:10.1029/2005JD006689, 2006. PDF
11. Sakulyanontvittaya, T., T. Duhl, C. Wiedinmyer, D. Helmig, S. Matsunaga, M. Potosnak, J. Milford, and A. Guenther, Monoterpene and Sesquiterpene Emission Estimates for the United States, Environ. Sci. Technol., 42(5), 1623{1629, doi:10.1021/es702274e, 2008.

--Bob Y. 09:39, 3 March 2010 (EST)