Emissions from an Unknown Source
Simulations from Multiple Samplers


  • Backward calculations are automatically configured in a pre-processor step
    from a sampling data file in DATEM format
  • A hypotethical example is used here because the CAPTEX case is not ideal
    due to the near constant wind direction
  • In the first example, the "numerator" case, the backward calculation
    emission rate is equal to the measured value giving more weight to the source
    regions contributing to the highest measurements

Reset Button

   clear GUI

Source location weighted by measurement

83 09 01 00

   Run start time

60

   Run duration

RP198309.gbl

   Meteorology

Starting location

   Doesn't matter

0.0

   Emission rate

60.0

   Emission duration

83 09 01 00 00

   Emission start

41.0 -73.0

   Concentration grid center

0.25 0.25

   Grid resolution

cnum

   Output file (for numerator)

83 09 01 00 00

   Grid start

83 09 03 12 00

   Grid stop

00 03 00

   Averaging period

5000

   namelist particle number

Step 1 - define measured data

hypo_meas.txt

   3-hour duration samples

numerator radiobutton

   set calculation Q=M

Step 2 - create backward CONTROL files

Step 3 - run dispersion simulations

Step 4 - display results

20

   set time aggregate to 20 (for 60 h)



Emission estimate calculation:
weighted by inverse of measurement

  • Emission rate is set to the inverse of the measurement (1/M)
  • From before, M=DQ, the model computes C=DQ
  • If Q is set to 1/M, the the model computes D/M
  • Then the model output is the same as 1/Q


    • Step 0 - Special Runs / Ensemble / Cleanup
    Step 1 - Set inverse radiobutton (Q=1/M)
    Step 2 - create backward CONTROL files
    Step 3 - run dispersion simulations
    Step 4 - display emission: inverse at source location

    Step X - Use Utility / Convert to Station
    Step Y - Extract value at 43N 75W
    Step Z - Inverse of 0.584x10-15 pg/h = 1700 g/h

    As the dilution increases, the emission rate must increase to maintain the same measurement, hence other engineering information can be used to estimated the maximum emission rate possible and hence the contour the limits the emission regions.