source: TOOLS/CMIP6_FORCING/AER_TROP_EMISSIONS/README @ 3567

DATE: 27/09/2016 
Olivier Boucher 

README on the reprocessing of the CMIP6 aerosol emissions for the IPSL-CM6 model 
(followed below by the README of the dataset itself by PNNL). We use the version of the 
data files put on the ESGF grid in late September 2017 with a sector dimension in the netcdf. 
The PNNL data are regridded to the IPSL-CM6-LR resolution (144x142) and remapped onto 
the species used by INCA using the script regrid.sh in the REGRID directory. The script uses 
a mix of ferret, idl and cdo routines. It covers the historical period 1850-2014 although 
fossil-fuel (emissions) are also available for 1750-1850. Only surface emissions are considered. 
3D emissions from aviation are currently discarded. Emissions from the different sectors are all 
grouped together, and FF and BB emissions are also grouped together by species. 
FF emissions of NOx are reported as NO2, while BB emissions of NOx are reported as NO. 
For AER configuration of INCA, we report NOx as NO (this may be different in other versions of INCA)
It is unclear as of now if BB emissions should be used as such (with their exact year) or time-filtered.

To run the script on ciclad: 
first edit regrid.job to modify running directory in 
qsub regrid.job

Update: 26/11/2016 
Use of v1.1 of the data 
/homedata/obolmd/AEROSOL_v1.1_old

Update: 22/03/2017 
update to v1.2 of the BB data 
changed remapbil to remapcon
/homedata/obolmd/AEROSOL

Update: 02/10/2017
report NOx emissions as NO for both FF and BB emissions

Update: 05/02/2018
New version of regrid.sh
Diffs: * updated paths to access new version of input data;
       * also some relevant corrections: underscores become hyphens for PNNL species-directories; VUA species-directory change from e.g. "CO-em-biomassburning" to "CO".


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DATE: June 18, 2016

SUMMARY

This emissions dataset was produced by the Community Emissions Data System (CEDS) Project (http://www.globalchange.umd.edu/ceds/). 

The June 18, 2016 data release is the final preindustrial 1750-1850 data for CMIP6. Included in this release are SO2, NOx, CO, NMVOC, NH3, BC, and OC emissions.  (1851-2014 data are being finalized). 

Please see the appropriate CMIP6 MIP protocol documents for use of these files. While we have supplied emissions over 1750-1850, the CMIP6 protocol calls for pre-industrial controls runs to use 1850 emissions.  

CO2 and CH4 emissions will be released in the near future.

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GRIDDED DATA

The emissions from 1750-1850 are provided at monthly resolution, on a 0.5 degree grid,  with 50-years per data file as per ESGF formatting conventions. (Finer grids can be produced if needed.) Emissions are relatively smooth over this time period, but annual data is supplied for consistency across the dataset. The files are in netcdf v4 (HDFv5) format with CF-compliant metadata.

The sectors in the netCDF files are:

sector  Description
AGR     Non-combustion agricultural sector
ENE     Energy transformation and extraction
IND     Industrial combustion and processes
RCO     Residential, commercial, and other
SHP     International shipping (including VOCs from oil tanker loading/leakage)
SLV     Solvents
TRA     Surface Transportation (Road, Rail, Other)
WST     Waste disposal and handling

Gridded aircraft emissions are also supplied in a separate file with 25 vertical layers (using the CMIP5 historical emissions Lamarque et al. 2010, as drawn from Lee et al., as a template).
These emissions are zero in 1850, but files are provided for consistency for all time periods.

The gridded emissions incorporate a monthly seasonal cycle by sector drawing largely from the ECLIPSE project.

VOC speciation is provided at the 25 species resolution used in HTAP and RETRO. 

For use in setting aerosol size distribution and additional speciation (if desired), an auxiliary dataset emissions providing emissions from solid biomass combustion is also provided. Note that these are a subset of emissions in the main files. These data, therefore, should NOT be added to the emissions in the main files.

Supplementary "checksum" .csv text files that provide total global mass for each sector, month, and year are also available at the project web site.

Filenames are in the following format:

MAIN EMISSION DATA
Gridded emissions:
[em_species]-em-anthro_input4MIPs_emissions_CMIP_CEDS-v2016-06-18_gr_YYYY01-ZZZZ12.nc
(where YYYY is the starting year contained in this file, and ZZZZ is the ending year)

Gridded aircraft emissions:
[em_species]-em-AIR-anthro_input4MIPs_emissions_CMIP_CEDS-v2016-06-18_gr_YYYY01-ZZZZ12.nc

SUPPLEMENTAL EMISSION DATA
Gridded biomass emissions:
[em_species]-em-SOLID-BIOFUEL-anthro_input4MIPs_emissions_CMIP_CEDS-v2016-06-18-supplemental-18_gr_YYYY01-ZZZZ12.nc

VOC speciation grids:
VOC01-alcohols-em-speciated-VOC_input4MIPs_emissions_CMIP_CEDS-v2016-06-18-supplemental-18_gr_YYYY01-ZZZZ12.nc
(There is a separate README file with further information on VOC speciation -- see project web site.)

Emissions are provided in units of mass flux, as a monthly average flux, as noted in the netCDF files. Units are total mass of the indicated species as follows:

SO2 : Mass flux of SOx, reported as SO2
NOx : Mass flux of NOx, reported as NO2
CO : Mass flux of CO
NMVOC : Mass flux of NMVOC (total mass emitted)
NH3 : Mass flux of NH3
BC : Mass flux of BC, reported as carbon mass
OC : Mass flux of OC, reported as carbon mass

For reference, the file: CEDS_gridcell_area_05.nc provides the grid cell areas used. (see project web site.)

As of this June 18 2016 release the preindustrial emissions are frozen and the future emissions timeseries that is being finalized will be consistent with these emissions.

In addition to gridded data, aggregate data by country and sector is also available in units of kilo-tonne (kt) per year (which will be published along with the journal paper). Note that country totals in these summary files do not include shipping or aircraft emissions, which are reported under the "global" iso. 

GRIDDING METHODOLOGY

Emissions were first estimated at the level of country, sector, and fuel. Emissions by sector were then mapped to spatial grids by country and sector (several intermediate gridded sectors were combined to form the final release sectors for CMIP6). Grid cells that contain more than one country have portions of emissions from each country. 

For recent decades, emissions were mapped to the grid level largely using the distribution of emissions from EDGAR (usually using year-specific EDGAR grids from 1970 through 2008). For some sectors, the emissions distribution varies over time, while for other sectors it was held constant. For most emission species, residential combustion is the dominant source by 1850, so emissions from the RCO sector were distributed using HYDE population distributions by 1900 (with blended spatial distributions between 1900 and 1970). For other sectors the emissions distribution within each country was held fixed before 1970. We aim to improve these distributions in the future, and would welcome contributions.

Because of the simplifying assumptions, emissions distributions, particularly in earlier years, should not be taken literally. Overall, however, anthropogenic emissions become small relative to either natural sources or mid-to-late 20th century emissions so we anticipate that these assumptions are not likely to have major impacts on global or regional modeling results.

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BRIEF NOTE ON 1850 EMISSIONS DATA VALUES

The following supplemental files:

OC_Global_RCP_Comparison.pdf
BC_Global_RCP_Comparison.pdf
CO_Global_RCP_Comparison.pdf
NH3_Global_RCP_Comparison.pdf
NMVOC_Global_RCP_Comparison.pdf
NOx_Global_RCP_Comparison.pdf
SO2_Global_RCP_Comparison.pdf

Show global CEDS pre-industrial emissions graphed against the historical emission data points used in the RCP/CMIP5 process (Lamarque et al. 2010).

Note that the CEDS emissions contain seasonality in all sectors, particularly the residential sector. This is an additional change from the RCP/CMIP5 emissions that is not apparent in the graphs showing annual emissions.

For the emissions in this period, the assumptions for residential biomass are the dominant emissions for most species. (Exceptions are NH3 where manure emissions are dominant, and NOx, where industrial combustion (higher temperatures), residential, and manure are all important). 

There are some notable differences compared to the 1850 data used in CMIP5 from Lamarque et al. (2010):

BC and OC: these are slightly different (OC slightly higher, BC slightly lower) due largely to updates in the SPEW (Bond et al.) emission factor database.

CO: Is higher due to the use of a biomass emission factor appropriate for lower temperature, less efficient residential combustion. 

NOx: Is lower for the same reason, the use of a biomass emission factor that is lower than that used in the previous version which did not distinguish between coal and biomass combustion in this period.

(These NOx and CO differences will persist in the early years, but are not indicative of emissions differences for more recent decades.)

Emissions prior to 1850 are estimated with an assumption of constant per-capita residential biomass consumption, fossil fuel emissions extrapolated using CDIAC CO2 emissions by fuel type, and emissions associated with metal smelting, coal coke and iron production extrapolated using metal production data by country.

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GENERAL PROJECT AND DATA INFORMATION

An overview of the CEDS project is available from the project web site, and a paper describing the CMIP6 dataset will be submitted to the CMIP6 GMD special issues.

Briefly, our aim for the CMIP6 data release is emissions data that reflect a reasonable estimate of trends over time by country and sector. This emissions data is calibrated to country-level emission estimates wherever these are available, with default data used for sectors and countries where defaults are not available. For most species EDGAR 4.3 (from 1970 - 2014) is used as the default data, while for SO2, region and sector-specific assumptions updated from Smith et al. are combined with EDGAR 4.3 process emissions.

In order to produce a dataset for release in time to be used for CMIP6, the initial focus of the project was to develop consistent trends over 1970 - 2014. Pre-industrial emissions were then finalized. In order to estimate 1850 emissions, residential and industrial coal and biomass consumption were estimated for the entire time period (drawing from CDIAC, Bond et al, and other sources). With these endpoints in place, emissions trends for the intervening years have been estimated. The result will be a continuous, consistent historical emission time series for CIMP6. Where relevant, emission factors will be converged to the selected early-industrial values.

Emissions from fuel combustion are estimated using fossil and solid biofuel combustion statistics over all years. For years before 1971 (non-OECD) or 1960 (OECD), fuel combustion is estimated using either direct estimates or by trending fossil fuel combustion using CDIAC CO2 emissions. 

Emissions from non-combustion sectors are taken from inventory data in recent decades, and trended back before (generally) 1970 using an appropriate proxy data series. Some of these proxies are only available globally. While global and regional trends using this procedure appear to be reasonable, some anomalies are present at the country level. In the future we will refine these estimates by collecting additional country-level proxy data. As noted above, anthropogenic emissions start to become smaller relative to other sources by the beginning of the 20th century, so we anticipate that are not likely to have major impacts on global or regional modeling results.

This dataset will continue to be refined after the CMIP6 data release and we welcome collaboration and engagement to improve historical emissions data. 

Country level emission data that are incorporated in this data release include:

European Countries: Country data as reported to EMEP
New Zealand, Belarus: UNFCCC reported data
USA: US EPA Trends
Canada: Environment Canada
Argentina: Country submission to UNFCCC
China: MEIC Inventory (2008, 2010, 2012)
South Korea: http://airemiss.nier.go.kr/
Japan: REAS historical inventory (preliminary updated)
Australia: National Emissions Inventory
Taiwan: National Emissions Inventory
Other Asia: REAS 2.1 historical inventory

The methods and results for this data will be documented in a paper to be submitted here: http://www.geosci‐model‐dev.net/special_issue590.html.

Please contact: ssmith@pnnl.gov for further details or questions about this dataset.

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