EPA/NEI11 North American emissions

From Geos-chem
Jump to: navigation, search

The EPA/NEI11 emissions inventory has been superseded by EPA/NEI2016.

On this page we shall provide an overview of the National Emissions Inventory produced by the US EPA (aka EPA/NEI2011). This inventory has been incorporated into GEOS-Chem v10-01 and newer versions via the HEMCO emissions component.



The EPA/NEI2011 data were processed by Katherine Travis onto a 0.1° lon x 0.1° lat grid, with 6 vertical levels. Original gridded data on a 12 km x 12km grid as provided by EPA. Emissions have been processed using the 2011 EPA SMOKE platform into GEOS-Chem emissions for 2011. These emissions have been implemented into GEOS-Chem v10-01 via the HEMCO emissions component. Please contact Katherine Travis if you are interested in this inventory.

--Bob Y. 11:35, 19 March 2015 (EDT)


We acknowledge the U.S. Environmental Protection Agency for providing 2011 North American emission inventories. These emission inventories are intended for research purposes using information from the 2011-based modeling platform as a starting point.

A technical document describing the 2011 modeling platform can be found here: https://www.epa.gov/sites/production/files/2015-10/documents/nei2011v2_tsd_14aug2015.pdf

The source code for the EPA/NEI2011 emissions is located in module nei2011_anthro_mod.F90.

Biofuel Emissions

The EPA/NEI11 North American emissions inventory contains biofuel emissions.

Monthly mean emissions

This update was included in v11-02a and approved on 12 May 2017.

Starting in GEOS-Chem v11-02a, monthly mean NEI2011 emissions are the default emissions used over the United States. These emissions use the logical switch NEI2011_MONMEAN in the HEMCO configuration file. The monthly mean emissions were implemented in an attempt to improve model run time. The original hourly NEI2011 emissions are still included as an option for users that want more precise emissions over the United States.

Monthly mean emissions can be found at:


The monthly mean emissions were computed from the original hourly emissions using the CDO monmean operator. The scripts used to create the monthly files can be found in the scripts subdirectory in NEI2011/v2017-02-MM/. Day-of-week scale factors from NEI99 and time-of-day scale factors from EDGAR and GEIA are applied to the monthly mean emissions. Day-of-week scale factors were not available for all VOCs, so a "generic" VOC scale factor is applied to those species. Scale factor NEI99_DOW_ACET was chosen for the generic VOC scale factor, but this may be changed in the future if deemed necessary.

--Melissa Sulprizio (talk) 20:04, 8 March 2017 (UTC)

Recommended emissions settings

We recommend that you turn on the NEI2011 emissions if your simulation covers the period 2006 or later. This will override the default underlying global emissions (e.g. EDGAR) over the United States. Monthly mean NEI2011 emissions are the default emissions used in GEOS-Chem v11-02 and later versions for all simulations, except nested grid simulations over North America which still use the hourly NEI2011 emissions by default. Hourly NEI2011 emissions are still an option in GEOS-Chem v11-02 and later versions. Users may choose to turn on hourly NEI2011 emissions by changing the NEI2011_HOURLY setting to true in the HEMCO configuration file. Note, however, that either NEI2011_HOURLY OR NEI2011_MONMEAN should be used, not both.

--Melissa Sulprizio (talk) 20:04, 8 March 2017 (UTC)

Annual Scale Factors

We use scale factors from EPA's National Tier1 CAPS (based on NEI2011 version 1) to scale NEI2011 emissions to other years within the period 2006–2013. These scale factors are shown in the table below.

Species 2006 2007 2008 2009 2010 2011 2012 2013
CO 1.271 1.227 1.104 0.998 1.019 1.000 0.981 0.962
NOx 1.337 1.255 1.172 1.097 1.034 1.000 0.939 0.887
PM2.5 1.006 1.034 0.996 0.995 0.993 1.000 0.995 0.991
SO2 2.038 1.813 1.600 1.408 1.200 1.000 0.800 0.738
VOC 1.083 1.093 1.011 1.000 1.016 1.000 0.986 0.971
NH3 0.966 1.002 1.019 1.015 1.010 1.000 0.999 0.998

If you are using the NEI2011 emissions for am model simulation between the years 2006–2013, you can use the appropriate scale factor from the table above. (These have been included in the HEMCO configuration files that ship with GEOS-Chem.)

On the other hand, if you are performing a model simulation for years prior to 2006, we recommend that you use an older emissions inventory such as NEI2005.

--Bob Y. 17:55, 18 March 2015 (EDT)

2013 SO2 and BC Scale Factors

For 2013, we decrease the SO2 scale factor from 0.738 to 0.613 based on surface station and wet deposition data. We also decrease BC by an additional 30% in 2013 based on SEAC4RS observations. For more information, see Kim et al, 2015 or contact Patrick Kim (kim68@fas.harvard.edu).

Mapping VOCs from CBO5 to GEOS-Chem

The emissions for NEI11 were provided to us in units of moles/s for gaseous species, and g/s for particulate species, on a 12km x 12km lambert conical conformal grid. We converted the units to kg/m2/s for input to GEOS-Chem. The NEI inventory provides VOCs lumped according to the CBO5 chemical mechanism. Emissions of acetone (ACET), propane (C3H8), and methyl ethyl ketone (MEK), and >C4 alkanes (ALK4) are lumped into the PAR species provided in NEI11. To split PAR into these species, we take the top 50 VOCs from Simon et al. [2010] and determine the PAR weighting for each from Yarwood et al. [2005]. The result is that 6% of PAR is ACET, 3% is C3H8, 2% is MEK, and 87% is ALK4.

Per recommendation by EPA, we map PAR (alkanes) as follows:
C3H8 = 0.03 * PAR
MEK = 0.02 * PAR
ACET = 0.06 * PAR
ALK4 = 0.87 * PAR

The remaining fraction is BENZ, which is double-counted in PAR.

We followed the mapping from http://wiki.seas.harvard.edu/geos-chem/index.php/GEOS-Chem_to_CMAQv5.0 for the following VOCs.

0.5 OLE + 0.5 IOLE = PRPE

Simon, H., Beck, L., Bhave, P. V., Divita, F., Hsu, Y., Luecken, D., Mobley, J. D., Pouliot, G. A., Reff, A., Sarwar, G., and Strum, M.: The development and uses of EPA's SPECIATE database, Atmospheric Pollution Research, 196-206, 10.5094/apr.2010.026, 2010.
Yarwood, G., Sunja, R., Yocke, M., and Whitten, G. Z.: Updates to the Carbon Bond Chemical Mechanism: CB05, 2005.

Emissions Totals for August 2013

  N. E. I. 2011 U. S. A.   E M I S S I O N S

 NEI2011 anthro  CO    for year 2013 and month 8:  4.688  [ Tg CO ]
 NEI2011 anthro  NO    for year 2013 and month 8:  0.2540  [ Tg N  ]
 NEI2011 anthro  NO2   for year 2013 and month 8:  0.027  [ Tg N  ] 
 NEI2011 anthro  HNO2  for year 2013 and month 8:  0.002  [ Tg N  ] 
 NEI2011 anthro  ALD2  for year 2013 and month 8:  0.008  [ Tg C  ]
 NEI2011 anthro  RCHO  for year 2013 and month 8:  0.011  [ Tg C  ]
 NEI2011 anthro  C2H6  for year 2013 and month 8:  0.063  [ Tg C  ]
 NEI2011 anthro  C3H8  for year 2013 and month 8:  0.015  [ Tg C  ]
 NEI2011 anthro  PRPE  for year 2013 and month 8:  0.007  [ Tg C  ]
 NEI2011 anthro  ACET  for year 2013 and month 8:  0.030  [ Tg C  ]
 NEI2011 anthro  ALK4  for year 2013 and month 8:  0.438  [ Tg C  ]
 NEI2011 anthro  MEK   for year 2013 and month 8:  0.011  [ Tg C  ]
 NEI2011 anthro  CH2O  for year 2013 and month 8:  0.038  [ Tg C  ]
 NEI2011 anthro  SO2   for year 2013 and month 8:  0.218  [ Tg S  ]
 NEI2011 anthro  SO4   for year 2013 and month 8:  0.002  [ Tg S  ]
 NEI2011 anthro  NH3   for year 2013 and month 8:  0.326  [ Tg NH3 ]
 NEI2011 anthro  OC    for year 2013 and month 8:  0.044  [ Tg C  ]
 NEI2011 anthro  BC    for year 2013 and month 8:  0.022  [ Tg C  ]
 NEI2011 anthro  BENZ  for year 2013 and month 8:  0.022  [ Tg C  ]
 NEI2011 anthro  TOLU  for year 2013 and month 8:  0.089  [ Tg C  ]
 NEI2011 anthro  XYLE  for year 2013 and month 8:  0.080  [ Tg C  ]
      • This inventory is still being processed, numbers are preliminary.

Agricultural sector

NH3 emissions scaling

Jenny Fisher wrote:

NH3 emissions from agricultural sources in the NEI inventory are scaled to match optimized emissions from the MASAGE_NH3 inventory (Paulot et al., 2014). MASAGE_NH3 provides monthly emissions at 2°x2.5° resolution for 2005-2008, while NEI provides hourly emissions at the native model resolution for 2010 (2011 if we are talking about NEI2011!).
To compare the two, we first average MASAGE_NH3 over years (in 2005-2008) to reduce the influence of interannual variability. We regrid NEI agricultural emissions to the coarser resolution of MASAGE_NH3 and sum over days and hours to derive monthly totals. We then calculate the ratio between the two inventories for each month and each 2° x2.5° grid square. These ratios are applied at runtime to the high-resolution hourly NEI emissions, allowing us to retain the spatial and temporal variability in NEI while matching the optimized totals from MASAGE_NH3.

--Bob Y. 18:13, 27 February 2015 (EST)

NEI 2011 settings for HEMCO

In this section we shall post some information about how to customize the NEI 2011 emissions settings in the HEMCO_Config.rc configuration file for your simulation.

Using NEI 2011 emissions outside of the range of 2006-2013

Jessica Belle-Hartman wrote:

We had a quick question about using NEI 2005 vs NEI 2011 for the years prior to 2006. If we use NEI 2011 for 2005, will it scale the emissions or simply use 2006 emissions? Is it better to switch between NEI 2005 and NEI 2011 based off of the year, or use NEI 2011 for a full simulation time series?

Christoph Keller replied:

If you use the default HEMCO settings and enable both NEI 2005 and NEI 2011, GEOS-Chem will use NEI05 up to year 2006 and switch to NEI11 afterwards. If you disable NEI05, then NEI11 will be used from year 2006 onwards because the valid time range of NEI 2011 is restricted to years 2006 to 2013:

     0 NEI11_SURFACE_NO $ROOT/NEI2011/v2015-03/$MM/NEI11_0.1x0.1_2011$MM$DD.nc  NO  2006-2013/1-12/1-31/* R xy  kg/m2/s  NO  251/1007  1/2 50

You can lift the time range restriction flag to use NEI11 for years outside of 2006-2013 by changing the time range flag from R to C (aka "cycle"):

     0 NEI11_SURFACE_NO $ROOT/NEI2011/v2015-03/$MM/NEI11_0.1x0.1_2011$MM$DD.nc  NO  2006-2013/1-12/1-31/* C xy  kg/m2/s  NO  251/1007  1/2 50

This will tell HEMCO to use the NEI 2011 emissions scaled to year 2006 for years prior to 2006, and NEI 2011 emissions scaled to 2013 for years after 2013.

--Bob Yantosca (talk) 15:28, 13 May 2016 (UTC)

Adding scale factors for years outside the NEI 2011 range

Jessica Belle-Hartman wrote:

So, it sounds like mixing NEI 2005 and 2011 is the default behavior and is not expected to produce inconsistent results?

Christoph Keller replied:

I think it was done that way to ensure backwards compatibility. I don’t know what the effects are if you mix NEI 2005 and 2011. Personally, I think NEI 2011 is better than NEI 2005 but that’s just my opinion. If you run NEI 2011 for 2005 you might want to add an annual scale factor for 2005 to scale factors 251-257 - otherwise you won’t have an emission trend between 2005 and 2006:

    251 NEI11_NO_YRSCALE   X.XXX/1.337/1.255/1.172/1.097/1.034/1.0/0.939/0.887 - 2005–2013/1/1/0 C xy 1 1

I think Katie Travis computed the scale factors for 2006-2013 based on total US NEI emissions.

--Bob Yantosca (talk) 15:35, 13 May 2016 (UTC)

Using local time with NEI 2011 emissions

Christoph Keller replied:

HEMCO interprets all gridded data in UTC time. If your gridded data is in local time you can use the local time flag in the source time attribute of the HEMCO configuration file, for example:

    0 MACCITY_CO $ROOT/MACCity.nc CO 1980-2014/1-12/1-31/LH C xy kg/m2/s CO 1 1 1

According to Katie Travis (who prepared the NEI 2011 files), all NEI 11 files should be in UTC, e.g. the LA NOx morning peak should occur at about 3pm UTC.

If you are not sure about what is emitted in your simulation you can use the HEMCO diagnostics to prepare hourly emission output in netCDF format: in your HEMCO configuration file (settings section) make sure to set the output frequency to ‘Hourly’ and to link to your HEMCO diagnostics definition file (HEMCO_Diagn.rc):

    DiagnPrefix:                 HEMCO_diagnostics
    DiagnFreq:                   Hourly
    DiagnFile:                   HEMCO_Diagn.rc

In HEMCO_Diagn.rc you can then define the diagnostics you want to write out. For example, the following file would write out both total NO and NO just from NEI 2011:

    # Name    Spec ExtNr Cat Hier Dim Unit
    TOTAL_NO  NO   -1    -1  -1   2   kg/m2/s
    NEI11_NO  NO    0     1   50  2   kg/m2/s

If you then run GEOS-Chem it will create an hourly HEMCO diagnostics file (named HEMCO_diagnostics.YYYYMMDDHHMM.nc) with total NO emissions stored in netCDF variable TOTAL_NO and NEI 2011 NO emissions only in variable NEI11_NO.

--Bob Yantosca (talk) 15:41, 13 May 2016 (UTC)

Previous issues that are now resolved

Update mask file applied to NEI2011 emissions

This update was included in GEOS-Chem 12.2.0, which was released on 19 Feb 2019.

The land mask applied to NEI emissions has been updated from:

1007 NEI11_MASK  $ROOT/MASKS/v2018-09/USA_LANDMASK_NEI2011_0.1x0.1.20160921.nc LANDMASK 2000/1/1/0 C xy 1 1 -140/20/-50/60


1007 CONUS_MASK  $ROOT/MASKS/v2018-09/CONUS_Mask.01x01.nc                    MASK     2000/1/1/0 C xy 1 1 -140/20/-50/60

The old land mask covered regions of northern Mexico and southern Canada, acting to zero out regional emissions there. To avoid this, we use a new land mask for the US that was created from a high-resolution shapefile of country boundaries (found at http://thematicmapping.org/downloads/world_borders.php) and saved out on a 0.1° x 0.1° grid.

--Melissa Sulprizio (talk) 21:38, 28 January 2019 (UTC)

Default US emissions to NEI2011 after 2013

This fix was included in v11-02a and approved on 12 May 2017.

Jessica Morena wrote:

I simulated dates beyond the end of 2013 and used NEI 2011 emissions, for which scale factors only exist to the end of 2013. The time slice selection is currently set to R (range) and thus emissions defaulted to EDGAR for years beyond 2013. I have compared 2013 simulations using EDGAR and NEI2011 and found the NEI2011 simulation to be more consistent with ground-based measurements. Therefore, I think it would make sense to change the flag from R to C (cycling) so that NEI2011 is still used beyond 2013. i.e.
    0 NEI11_SURFACE_NO $ROOT/NEI2011/v2015-03/$MM/NEI11_0.1x0.1_2011$MM$DD.nc NO 2006-2013/1-12/1-31/* R xy kg/m2/s NO 251/1007 1/2 50
    0 NEI11_SURFACE_NO $ROOT/NEI2011/v2015-03/$MM/NEI11_0.1x0.1_2011$MM$DD.nc NO 2006-2013/1-12/1-31/* C xy kg/m2/s NO 251/1007 1/2 50
I believe that incorporating these changes into the HEMCO configuration file may help users interested in nested grid simulations and in simulating more recent dates to achieve better results.
--Melissa Sulprizio (talk) 23:11, 8 February 2017 (UTC)