Creating County Mask for DESID using shp2cmaq

CMAQ DESID
1

I am trying to use shp2cmaq to create a county mask file to use with DESID. I would then use DESID to reduce emissions in a group of counties that would be a region family. I am trying to create the mask for the CMAQ version 5.5 benchmark which uses the 2018_12NE3 grid. The county shape file I am using comes from a US Census tigerline file:

https://www.census.gov/cgi-bin/geo/shapefiles/index.php?year=2020&layergroup=Counties+%28and+equivalent%29

The tiger file contains the 5 digit state/county fips code in a column called GEOID. I call shp2cmaq using the tigerline zipfile with attrkey=‘GEOID’, gdnam=‘2018_12NE3’,
gdpath=‘/…/CMAQv5.4_2018_12NE3_Benchmark_2Day_Input/2018_12NE3/GRIDDESC’,
outpath=‘/…/CountyMask.nc’,
outformat=‘NETCDF3_CLASSIC’, srckey=‘intersection_area’,overwrite=True,verbose=1. The crs for the file is EPSG:4269.

The CountyMask.nc file that is created does not seem to function properly. Examining it with Panoply shows that the counties are overlapped with the grid in unknown units. Panoply output:

netcdf /home/…/CountyMask.nc {
dimensions:
TSTEP = 1;
VAR = 667;
DATE-TIME = 2;
LAY = 1;
ROW = 105;
COL = 100;
variables:
int TFLAG(TSTEP=1, VAR=667, DATE-TIME=2);
:units = “<YYYYJJJ,HHMMSS>”;
:long_name = "TFLAG ";
:var_desc = "TFLAG ";

float GEOID_09001(TSTEP=1, LAY=1, ROW=105, COL=100);
  :_FillValue = NaNf; // float
  :long_name = "GEOID_09001     ";
  :var_desc = "Fractional overlap of GEOID_09001 with 2018_12NE3                               ";
  :unit = "1               ";
  :units = "unknown";

float GEOID_09003(TSTEP=1, LAY=1, ROW=105, COL=100);
  :_FillValue = NaNf; // float
  :long_name = "GEOID_09003     ";
  :var_desc = "Fractional overlap of GEOID_09003 with 2018_12NE3                               ";
  :unit = "1               ";
  :units = "unknown";

Whereas Panoply indicates that the gridmask for states that comes with the Benchmark has the units of “fraction” as below:

netcdf /data1/CMAQ/DATA/CMAQv5.4_2018_12NE3_Benchmark_2Day_Input/2018_12NE3/GRIDMASK_STATES_12NE3.nc {
dimensions:
TSTEP = 1;
DATE-TIME = 2;
LAY = 1;
VAR = 49;
ROW = 105;
COL = 100;
variables:
int TFLAG(TSTEP=1, VAR=49, DATE-TIME=2);
:units = “<YYYYDDD,HHMMSS>”;
:long_name = "TFLAG ";
:var_desc = "Timestep-valid flags: (1) YYYYDDD or (2) HHMMSS ";

float AL(TSTEP=1, LAY=1, ROW=105, COL=100);
  :long_name = "AL              ";
  :units = "fraction";
  :var_desc = "AL fractional area per grid cell                                                ";

float AZ(TSTEP=1, LAY=1, ROW=105, COL=100);
  :long_name = "AZ              ";
  :units = "fraction";
  :var_desc = "AZ fractional area per grid cell                                                ";

How am I misusing shp2cmaq?
Thank you.