Emissions overview

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

Anthropogenic emissions

Please also see our table of species listed by inventory on our Anthropogenic emissions wiki page.

EDGAR (Default inventory)

Starting with v9-01-02, the default anthropogenic emissions in GEOS-Chem come from the global EDGAR emissions inventory. In previous versions, the GEIA/Piccot inventory was the default. EDGAR can be overwritten by one or more regional emissions inventories in various locations of the globe (e.g. N. America, Asia, Europe, etc.).

RETRO

RETRO anthropogenic VOC emissions are available beginning with version 9-01-02, and are the recommended default VOC emission inventories. The RETRO inventory has improved temporal and spatial resolution and a more inclusive suite of speciated NMVOCs than many of the other optional inventories.

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

The default biofuel inventory is that of Yevich and Logan [2003]. This inventory can be overwritten by:

• EPA/NEI99 biofuel emissions over N. America
• David Streets et al 2006 biofuel emissions over SE Asia

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

Biogenic emissions

MEGAN

Biogenic species (Isoprene, Monoterpenes, Methyl Butenol) are emitted following the MEGAN model inventory. 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.

GEIA

Originally, GEOS-Chem emitted biogenic species from the GEIA biogenic emissions inventory. This option was removed in version 9-01-03, but remains available as an option in previous versions.

Biomass burning

GFED is the recommended biomass burning emission inventory. GFED3 will be used for model versions 9-01-02 and later, while GFED2 is available for previous versions. GFED includes emission factors for gas-phase species (NOx, CO, ALK4, ACET, MEK, ALD2, PRPE, C3H8, CH2O, C2H6), aerosol species (SO2, NH3, BC, OC), and CO2.

Most of these are also anthropogenic emissions species.

--Mcooper 12:59, 9 August 2011 (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)

Inventory History

The following table describes important changes to the emission inventories:

Version	Released	Description	Contact
v9-01-02	Nov 2011	Retirement of GEIA biogenic emissions	E. Fischer (Harvard) D. Millet (U. Minnesota)
v9-01-02	Nov 2011	Historical SO2, NOx, BC and POA emissions	Eric Leibensperger (MIT)
v9-01-02	Nov 2011	Update biomass burning emissions to GFED3	Prasad Kasibhatla
v9-01-02	Nov 2011	Implementation of RETRO Anthropogenic VOC emissions	W. Reinhart, U. of Minnesota
v9-01-01	Feb 2011	Updated lightning parameterization and fix for cloud-top-height algorithm	L. Murray, Harvard
v9-01-01	Feb 2011	Updated volcanic SO2 emissions from Aerocom	J. Fisher (Harvard)
v8-03-01	May 2010	Extension of annual anthropogenic scale factors to 2006	A. van Donkelaar, Dalhousie
v8-03-01	May 2010	Emissions for Nested NA/EU Simulations Nested Grid	A. van Donkelaar, Dalhousie
v8-03-01	May 2010	Emissions for Global 1 x 1.25 simulation capability	L. Lamsal, Dalhousie
v8-03-01	May 2010	Speciated biogenic emissions from MEGAN v2.1 now used in SOA code	H. Pye, Caltech
v8-02-04	Feb 2010	EPA/NEI2005 regional emissions inventory for North America	P. Le Sager (formerly Harvard), A. van Donkelaar (Dalhousie)
v8-02-04	Feb 2010	MEGAN v2.1 biogenic emissions	Mike Barkley, Edinburgh
v8-02-03	Oct 2009	ICOADS ship emissions	Chulkyu Lee, Dalhousie
v8-02-03	Oct 2009	Updated OTD/LIS redistribution factors for GEOS-5	Lee Murray, Harvard

Please see the following documentation for information on previous model versions:

• Description of anthropogenic emissions inventories in GEOS-Chem v8-02-03
• Description of anthropogenic emissions inventories in GEOS-Chem v8-01-04
• Table of available anthropogenic emissions inventories for use w/ GEOS-Chem (pre-v8)

Documents like these will no longer be produced. Information on the current model version can be found throughout the wiki.

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)

MAP_A2A regridding algorithm

This update was tested in the 1-month benchmark simulation v9-01-03k and approved on 27 Apr 2012.

Matt Cooper has replaced the existing GEOS-Chem regridding routines with an algorithm adapted from the MAP_A2A regridding package (developed by S.-J. Lin and refined by Bob Yantosca). The previous regridding routines sometimes involved two separate regridding processes, passing through the GEOS 1° x 1° grid, which could lead to loss of information. The new algorithm regrids emissions from any arbitrary horizontal grid to the current model resolution.

The new regridding algorithm includes a reworking of MAP_A2A, provided by Prasad Kasibhatla.

Prasad Kasibhatla wrote:

I discovered that the MAP_A2A gridding algorithm was smearing emissions incorrectly (though not in a major way) - seems to arise from mapping based on some sort of piecewise polynomial interpolation between grids, rather than simply using area-overlap fractions to apportion grid-average fluxes from old to new grid.

I put in a pretty simple fix, that you should be able to implement pretty easily. I basically modified the Xmap and Ymap routines and got rid of all the other subroutine calls - the calling sequence is the same so I suspect it should be pretty easy for you to modify MAP_A2A.

A couple of words of caution:

• my fix only works for regular lat-lon grids because it uses delta(longitude) and delta(sin(latitude)) to do the regridding
• my fix is exact for cases where you are regridding grid-average quantities (eg gridded emission fields), but I would do it differenty if I was regridding quantities that implicitly had sub-grid variation (eg if one assumes that a variable represents the center of a grid box and that there is a linear variation from one grid box center to another
• You might also be interested in how I set it up so it handles nested grids correctly. I created new functions called GET_IIIPAR and GET_JJJPAR (see attached grid_mod.F) that I use in regridding on a global grid, and then use GET_XOFFSET and GET_YOFFSET to cut out the nested grid portion.

--Melissa Payer 13:18, 16 March 2012 (EDT)

Bug fixes for the MAP_A2A regridding algorithm

Lee Murray found a typo in the latlon_geos1x1.txt file used for the MAP_A2A regridding algorithm.

Lee Murray wrote:

There is definitely an error in the erroneous missing of 0.5ºW in the geos file. This led to inherent inconsistencies in how latlon_geos1x1.txt and latlon_generic.txt were indexed by GEOS-Chem, since latlon_geos1x1 made up for the missing longitude edge by doubling up both 180.5ºW/179.5ºE and 179.5ºW/180.5ºE. latlon_generic.txt only repeats 180ºW/180ºE.

Several bugs were also fixed in the MAP_A2A regridding code to ensure consistency in the use of IM and JM, the number of longitude and latitude centers on the input grid.

Prasad Kasibhatla wrote:

I think we are all on the same page, but just to make sure here is what I suggest we agree on:

That the calling sequence for DO_REGRID_A2A be:

     CALL DO_REGRID_A2A(FILENAME,IM,JM,INGRID,OUTGRID,PERAREA)

where

IM = number of grid boxes in E-W direction (not number of lon edges)

JM = number of grid boxes in N-S direction (not number of lat edges)

so that the dimension of INGRID is (IM,JM) and IM+1 and JM+1 are number of lon edges and number of lat edges, respectively.

That the calling sequence for MAP_A2A be

     CALL MAP_A2A( IM,    JM,    INLON, INSIN, INGRID,   &
                   IIPAR, JJPAR, LON2,  SIN2,  OUTGRID,  0, 0)

where INLON, INSIN, and INGRID are dimensioned IM+1, JM+1, and (IM,JM), respectively, and LON2, SIN2, and OUTGRID are dimensioned IIPAR+1, JJPAR+1, and (IIPAR, JJPAR), respectively.

So, for example, when the input grid is a generic 1x1 grid, and the output grid is the geos 1x1 grid:

     IM=360
     JM=180
     INLON(1)=-180
     INLON(361)=180
     INSIN(1)=-1
     INSIN(181)=1
     LON2(1)=-180.5
     LON2(361)=179.5
     SIN2(1)=-1
     SIN2(181)=1

One last suggestion - if possible, change variable names LON2 and SIN2 to OUTLON and OUTSIN.

--Melissa Payer 11:44, 8 June 2012 (EDT)