Hestia SWIFL Fossil Fuel Carbon Dioxide (FFCO2) Data Product 
- AZ_urban Version 1.0 - WRF 2km grid
created: Feb 26, 2025

Contact:
     Anna Kato (anna.kato@nau.educ)
     Kevin Gurney (kevin.gurney@nau.edu)
     Northern Arizona University

HESTIA-SWIFL DATA PRODUCT FOR AZ URBAN AREAS
The Hestia-SWIFL AZ_urban v1.0 FFCO2 data represent emissions due to the combustion of fossil fuel 
and cement production in Arizona urban areas. The exact spatial extent is defined by the ASU Weather Research Forecast (WRF) simulation grid. 
The emissions are generated using a bottom-up/engineering approach and are tied to results generated by 
the Vulcan Project version 4, an effort to quantify space/time-resolved FFCO2 emissions for the entire 
United States landscape. A large number of data sources are combined to 
best estimate FFCO2 emissions at fine scales such as air quality emissions data, traffic flow data, 
building information, sociodemographic information, and fuel statistics. The native spatial 
resolution of the Hestia FFCO2 emissions data product is a combination of points, lines, and 
polygons dictated primarily by the underlying data sources and the Vulcan FFCO2 emissions output. 
The output made available here places this information into a regularized 2 km x 2 km grid at hourly and annual 
temporal resolutions.

FAIR USE DISCLAIMER
The Hestia data product is an estimation of fossil fuel CO2 (FFCO2) emissions at very fine scales in 
time and space. It should be considered a "climatology" of emissions rather than the "weather" of 
emissions such that the estimates represent "typical" emissions at a given time and place (average 
conditions). Hence, it is not appropriate to use the data in comparison to short-term "campaign 
style" atmospheric measurements (e.g. 5 days of continuous monitoring at a specific location) 
without consideration of and reference to the mismatch between the measurement and the Hestia 
estimation approach. Users are encouraged to contact Kevin Gurney for updates and consultation 
on such potential use.

SECTORAL COMPOSITION
In addition to the total FFCO2 emissions in each gridcell for a unit of time, emissions are available for nine individual 
sectors (Electricity Production, Residential, Commercial, Industrial, 
Onroad, Nonroad, Airport, Railroad, plus stoichiometric release from cement production). 
The FFCO2 emissions are Scope 1 only and therefore the emissions driven by electricity consumption are located at power production facilities. 

DATA FILE NAMES AND FILE STRUCTURE 
The Hestia-SWIFL FFCO2 emissions are represented using two time-resolutions: annual and hourly for 
the 4 year timespan of 2019 to 2022, inclusive.  The 2km x 2km gridded FFCO2 emissions are stored in 
netCDF files and represent the emissions resulting from integration of all point, line, and polygon 
elements within a gridcell (using area or length proportions for line and polygon elements that straddle 
gridcells). The annual files contain a 246-row by 231-column matrix with double-precision values 
arranged in row-major order - each row runs longitudinally and each column latitudinally with the first 
grid cell located at the northwestern corner. Each of the hourly emissions files contain 8760 (for the 
years other than 2020) or 8784 (for the year 2020) grid arrays, each of which is a double-precision 
matrix of the same structure as that in the annual files. The time domain reflects local time. The grid 
details are provided in Table 1. All the gridded FFCO2 emissions are in units of metric tons of carbon (tC) 
per gridcell. Sector-specific results are available upon request.
 
Table 1. 2km x 2km grid parameters

Parameter
  dimensions:
    X = 231;
    Y = 246;
    T = 8760;
  variables:
    double X(X=231);
      :units = "2km";
      :long_name = "X";

    double Y(Y=246);
      :units = "2km";
      :long_name = "Y";

    int T(T=8760);
      :units = "hour";
      :long_name = "T";
}

Projection: "AZ_North_America_Lambert_Conformal_Conic"

WKT:
PROJCRS["AZ_North_America_Lambert_Conformal_Conic",
    BASEGEOGCRS["NAD83",
        DATUM["North American Datum 1983",
            ELLIPSOID["GRS 1980",6378137,298.257222101,
                LENGTHUNIT["metre",1]],
            ID["EPSG",6269]],
        PRIMEM["Greenwich",0,
            ANGLEUNIT["Degree",0.0174532925199433]]],
    CONVERSION["unnamed",
        METHOD["Lambert Conic Conformal (2SP)",
            ID["EPSG",9802]],
        PARAMETER["Latitude of false origin",40,
            ANGLEUNIT["Degree",0.0174532925199433],
            ID["EPSG",8821]],
        PARAMETER["Longitude of false origin",-112,
            ANGLEUNIT["Degree",0.0174532925199433],
            ID["EPSG",8822]],
        PARAMETER["Latitude of 1st standard parallel",30,
            ANGLEUNIT["Degree",0.0174532925199433],
            ID["EPSG",8823]],
        PARAMETER["Latitude of 2nd standard parallel",60,
            ANGLEUNIT["Degree",0.0174532925199433],
            ID["EPSG",8824]],
        PARAMETER["Easting at false origin",0,
            LENGTHUNIT["metre",1],
            ID["EPSG",8826]],
        PARAMETER["Northing at false origin",0,
            LENGTHUNIT["metre",1],
            ID["EPSG",8827]]],
    CS[Cartesian,2],
        AXIS["(E)",east,
            ORDER[1],
            LENGTHUNIT["metre",1,
                ID["EPSG",9001]]],
        AXIS["(N)",north,
            ORDER[2],
            LENGTHUNIT["metre",1,
                ID["EPSG",9001]]]]
				

The gridded output files follow a naming convention that indicates the key attributes of the file. 
For example, the file "AZ_urban_elecprod.hourly.2km.ffco2.2019.nc" indicates the grid resolution (2km), 
the emissions domain (AZ_urban), the version number (v1.0), the sector (e.g. "total", "onroad", "com", etc), 
the time resolution (e.g. "annual", "hourly"), emissions data ("ffco2"), and the data year (2019). 
See the Table 2. for the filename reference and descriptions.

Table 2. sector names and descriptions
------------------------------------------------------------------------------------------
| sector names (filenames)		| descriptions
| airport						| aircraft emissions from Landing and Take-Off (up to 3000km)
| cement						| stoichiometric emissions from cement production
| commercial					| emissions related to commercial activities
| elecprod						| emissions from electricity production at the powerplants
| industrial					| emissions related to industrial activities
| nonroad						| emissions from off-road vehicles and other mobile sources
| onroad						| vehicle emissions on highways/roadways
| railroad						| railroad emissions (electricity-driven rails are not included)
| residential					| emissions related to residential activities
------------------------------------------------------------------------------------------

For questions on file formats and updates, please contact Anna Kato and/or Kevin Gurney.