View source for Emissions overview

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

== Anthropogenic emissions ==

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

* [http://acmg.seas.harvard.edu/geos/word_pdf_docs/emissions_v8_02_03.pdf Description of anthropogenic emissions inventories in GEOS-Chem v8-02-03] 
* [http://wiki.seas.harvard.edu/geos-chem/images/Anth_emiss_gc_v8-01-04.pdf Description of anthropogenic emissions inventories in GEOS-Chem v8-01-04] 
* [http://acmg.seas.harvard.edu/geos/word_pdf_docs/INVENTORY_GC_public-pre_v8.pdf Table of available anthropogenic emissions inventories for use w/ GEOS-Chem (pre-v8)] 

=== Baseline inventory ===

By default, GEOS-Chem uses the [[Anthropogenic emissions#GEIA/Piccot|GEIA/Piccot]] inventory with 10 gas-phase species:

{| border=1 cellpadding=5 cellspacing=0
|- bgcolor="#CCCCCC" align="center"
! Species
! Name
! Equivalent # of carbons
|- align="center"
| NO<sub>x</sub>
| Odd nitrogen = NO<sub>2</sub> + NO + NO<sub>3</sub> + HNO<sub>2</sub>        
|&nbsp;
|- align="center"
| CO
| Carbon monoxide        
|&nbsp;
|- align="center"
| PRPE
| >= C3 Alkanes        
| 3
|- align="center"
| C<sub>3</sub>H<sub>8</sub>
| Propane        
| 3
|- align="center"
| ALK4
| >= C4 Alkenes
| 4
|- align="center"
| C<sub>2</sub>H<sub>6</sub>
| Ethane
| 2
|- align="center"
| ACET
| Acetone
| 3
|- align="center"
| MEK
| Methyl Ethyl Ketone
| 4
|- align="center"
| ALD2
| Acetaldehyde
| 3
|- align="center"
| CH<sub>2</sub>O
| Formaldehyde
|&nbsp;
|}

=== Optional inventories ===

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

These emissions may be further overwritten by one or more [[Anthropogenic emissions#Regional inventories|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#Anthropogenic emissions|aerosol emissions page]] for more information about these inventories.

=== Ship emissions ===

[[Ship emissions|Emissions from ship exhaust]] from several global (e.g. [[Anthropogenic emissions#EDGAR|EDGAR]]) and regional (e.g. [[Anthropogenic emissions#EMEP|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, [[Scale factors for anthropogenic emissions|interannual scale factors must be applied]].

== Biofuel emissions ==

GEOS-Chem emits the same 12 biofuel species as for [[#Baseline inventory|anthropogenic emissions]] listed above.  The default inventory is that of [[Biofuel emissions#Yevich and Logan|''Yevich and Logan'' <nowiki>[2003]</nowiki>]].  This inventory can be overwritten by:

* [[EPA/NEI99 North American emissions|EPA/NEI99 biofuel emissions]] over N. America
* [[Anthropogenic emissions#David Streets|David Streets et al 2006 biofuel emissions]] over SE Asia

Please see our [[Biofuel emissions|biofuel emissions wiki page]] for more detailed information.

== Biogenic emissions ==

=== GEIA ===

By default, GEOS-Chem emits the following species from the [[Biogenic emissions#GEIA|GEIA biogenic emissions inventory]]:

{| border=1 cellpadding=5 cellspacing=0
|- bgcolor="#CCCCCC" align="center"
! Species
! Name
! Generic formula
! Equivalent # of carbons
|- align="center"
| ISOP
| Isoprene      
| C<sub>5</sub>H<sub>8</sub>
| 5
|- align="center"
| MONOT
| Monoterpenes
| C<sub>10</sub>H<sub>16</sub>
| 10
|- align="center"
| MBO
| Methyl Butenol
| C<sub>5</sub>H<sub>10</sub>O
| 5
|- align="center"
| ACET
| Acetone       
| CH<sub>3</sub>COCH<sub>3</sub>
| 3
|- align="center"
| ALK4 (scaled from ISOP)
| >=C4 alkenes 
|&nbsp;
| 4
|}

=== MEGAN ===

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

#Isoprene
#Monoterpenes
#Methyl Butenol

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

Also see our [[Emissions Working Group#GEOS-Chem Emissions Issues(please add yours!)|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 [http://acmg.seas.harvard.edu/publications/duncan2002a.pdf ''Duncan et al'' <nowiki>[2003]</nowiki>]:

# NOx
# CO
# ALK4
# ACET
# MEK
# ALD2
# PRPE
# C3H8
# CH2O
# C2H6
# SO2
# NH3
# BC
# OC
# CO2 (NOTE: for offline simulations only!) 

Most of these are also [[#Anthropogenic emissions|anthropogenic emissions species]].

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

--[[User:Bmy|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:

# [[Aircraft emissions#NOx|NOx emissions from aircraft]]
# [[Lightning NOx emissions|NOx emissions from lightning]]
# [[Soil NOx emissions|NOx emissions from soils]]

--[[User:Bmy|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.)

--[[User:Bmy|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).

At present, the model does a 2-step regridding 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 CO<span><sub>2</sub> 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.



[[Image:Example.jpg]]


--[[User:Ray|Ray Nassar]] 16:22, 10 May 2011 (EDT)