Emissions overview

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Revision as of 20:32, 10 May 2011 by Ray (Talk | contribs) (Emissions regridding issues)

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Here is a quick overview of the emissions inventories that are currently available in GEOS-Chem.

Anthropogenic emissions

Please see our anthropogenic emissions wiki page for details about all global and regional inventories, or download the following documentation:

Baseline inventory

By default, GEOS-Chem uses the GEIA/Piccot inventory with 10 gas-phase species:

Species Name Equivalent # of carbons
NOx Odd nitrogen = NO2 + NO + NO3 + HNO2  
CO Carbon monoxide  
PRPE >= C3 Alkanes 3
C3H8 Propane 3
ALK4 >= C4 Alkenes 4
C2H6 Ethane 2
ACET Acetone 3
MEK Methyl Ethyl Ketone 4
ALD2 Acetaldehyde 3
CH2O Formaldehyde  

Optional inventories

It is the usual practice to replace the NOx, CO, and SOx from the GEIA/Piccot inventory with data from the global EDGAR emissions inventory.

These emissions may be further overwritten by one or more regional emissions inventories in various locations of the globe (e.g. N. America, Asia, Europe, etc.).

Anthropogenic emissions of aerosols

Several aerosol species have anthropogenic emissions. Please see our aerosol emissions page for more information about these inventories.

Ship emissions

Emissions from ship exhaust from several global (e.g. EDGAR) and regional (e.g. EMEP etc.) inventories can also be selected.

Annual scale factors

Several of the emission inventories are for a particular year or range of years. To obtain emissions for years outside of the given range, interannual scale factors must be applied.

Biofuel emissions

GEOS-Chem emits the same 12 biofuel species as for anthropogenic emissions listed above. The default inventory is that of Yevich and Logan [2003]. This inventory can be overwritten by:

Please see our biofuel emissions wiki page for more detailed information.

Biogenic emissions


By default, GEOS-Chem emits the following species from the GEIA biogenic emissions inventory:

Species Name Generic formula Equivalent # of carbons
ISOP Isoprene C5H8 5
MONOT Monoterpenes C10H16 10
MBO Methyl Butenol C5H10O 5
ACET Acetone CH3COCH3 3
ALK4 (scaled from ISOP) >=C4 alkenes   4


The following species may be overwritten with the MEGAN inventory (this is now recommended)!

  1. Isoprene
  2. Monoterpenes
  3. Methyl Butenol

Please see our MEGAN biogenic emissions wiki page for more information.

Also see our Isoprene Emission Estimates in the Literature page for Isoprene Emission Estimates in the literature.

Biomass burning

By default GEOS-Chem uses 15 biomass burning species from Duncan et al [2003]:

  1. NOx
  2. CO
  3. ALK4
  4. ACET
  5. MEK
  6. ALD2
  7. PRPE
  8. C3H8
  9. CH2O
  10. C2H6
  11. SO2
  12. NH3
  13. BC
  14. OC
  15. CO2 (NOTE: for offline simulations only!)

Most of these are also anthropogenic emissions species.

All of these species can be overwritten by GFED2 monthly, 8-days, or 3hr biomass emissions.

--Bob Y. 14:40, 17 March 2010 (EDT)

Other NOx emissions sources

Please see the following wiki pages for information about other sources of NOx emissions:

  1. NOx emissions from aircraft
  2. NOx emissions from lightning
  3. NOx emissions from soils

--Bob Y. 14:40, 17 March 2010 (EDT)

Aerosol emissions

Please see our Aerosol emissions wiki page for a full description of the inventories which contain aerosol species (e.g. SO2, SO4, NH3, NH4, etc.)

--Bob Y. 14:40, 17 March 2010 (EDT)

Emissions regridding issues

Different regridding approaches have been tried in order to prepare for model simulations at the GEOS-5 native resolution of 0.5x0.667, or other high resolution possibilities.

With each step in regridding, information is reorganized in such a way that it cannot be recovered by later regridding in the reverse direction, therefore, optimal regridding is done in a single step. This means that when input emissions data are provided on a given grid, the optimal approach (to avoid losing information) is to leave them on that grid, read them into the model and regrid in the code to the desired resolution. This is the approach currently used for GFEDv2 which comes in on a generic 1x1 grid (360x180).

However, at present, the model does a 2-step regridding using functions from regrid_1x1_mod.f in the following way:

1) function DO_REGRID_G2G_1x1 regrids generic_1x1 --> GEOS_1x1

2) function DO_REGRID_1x1 regrids GEOS_1x1 --> desired resolution

The above is not equivalent to the single step regridding carried out in IDL (regridH.pro).

An alternative is to use the Fortran regridding code map_a2a (developed by S.-J. Lin and refined by Bob Yantosca). I have experimented with this in the model and have it working for some situations but the code has a single option for half-polar grids. This permits direct regridding from an input half-polar grid to an output half-polar grid, or an input full-polar grid to an output full-polar grid, but does not properly regrid between full-polar and half-polar.

Figures depicting CO2 differences in the net terrestrial exchange field which was on a generic 1x1 grid then regridded to 2x2.5 for a model simulation using different approaches (idl regridh.pro, regrid_1x1_mod, and map_a2a) are shown below, to emphasize that a single-step regridding approach is the best universal approach.


-- Ray Nassar 16:22, 10 May 2011 (EDT)