1. Part 4: Local scale dispersion calculation
HANDS-ON EXERCISES
Part 4: Local scale dispersion calculation
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PC-HYSPLIT WORKSHOP 1

2. Local Scale Dispersion Calculation
Presented on the following slides is an example of how to apply many of the concepts learned in the Pollutant Plume Simulation PowerPoint to a small scale emergency response application. Try to setup and run the model without viewing the additional slides, however if you have difficulty the additional slides will take you step by step through the setup.
It is recommended to click on the Reset button of the main HYSPLIT menu before proceeding in order to clear out any old cases in the working directory.
Note: These runs were produced using HYSPLIT version 4.9 (released January 2010). Slight differences are possible with older/newer versions of the model.
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PC-HYSPLIT WORKSHOP 2

3. Local Scale Dispersion Calculation
HYSPLIT can be configured for applications such as emergency response, when the scale of the simulation is on the order of 1-30 km. This assumes that the meteorological data used is representative of the flow at these scales.
For this example, you are given the following information to set up a HYSPLIT run
Source location: N W
Source height: a column of pollutant between 10m and 100m
Release start time: 1200 UTC 17 February 2009
Release stop time: 1300 UTC 17 February 2009
Forecast data: NAM 12 km NE tile
Provide to the requester: 1-hr average concentration at 100 m
4 range rings every 10 km
county map background
Google Earth (kmz) output
Additional hints: Grid Spacing: degrees lat/lon,
Grid Span: 1.0 degrees lat/lon,
3-D particle horizontal and vertical method,
Number of particles released per cycle: 5000,
maximum number of particles: 10000
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PC-HYSPLIT WORKSHOP

4. Local Scale Dispersion Calculation
Click Reset from the main menu
From the Concentration / Setup run menu, set:
Total run time: 1 hour,
NAM 12 km NE tile forecast data (hysplit.t12z.namsf.NEtilew),
Starting time: 1200 UTC 17 February ( ),
To enter a vertical line source, enter 2 starting locations at the same lat/lon but at 2 different heights: N and 100m,
From the Concentration / Setup run / Pollutant, Deposition and Grids setup:
1 hour emission,
1-hr average concentration at 100 m,
Grid Spacing of degrees, and Grid Span of 1.0 degrees lat/lon.
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PC-HYSPLIT WORKSHOP

5. Local Scale Dispersion Calculation
Using the Advanced / Configuration Setup / Concentration menu, set the following:
3-D particle horizontal and vertical method,
5000 particles released per cycle,
10000 maximum number of particles, and
Run using SETUP file
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PC-HYSPLIT WORKSHOP

6. Local Scale Dispersion Calculation
After running the model, set the Concentration Display menu to the following:
Output File: concplot
Number of rings to 4 every 10 km
Map background to /working/map_county
Zoom to 90%
Dyn-Exp contours
Turn on the contour outlines (Color) 
Turn on the Google Earth option
Execute Display
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PC-HYSPLIT WORKSHOP

7. Local Scale Dispersion Calculation
The resulting plume (below left) produces a narrow plume moving south-southeast into southern Maryland over the 1 hour period.
As will be discussed later, the Google Earth file (HYSPLITconc.kmz) was created in the /working directory and allows the emergency manager to overlay the plume with other geographic features (below right). This file can be provided directly to the emergency manager.
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PC-HYSPLIT WORKSHOP

8. Local Scale Dispersion Calculation
Now, assume that you were just told that the release only lasted for 15 minutes. Rerun the same case, but this time use the following modifications:
Release start time: 1200 UTC 17 February 2009
Release stop time: 1215 UTC 17 February 2009
Provide to the requester: 10 minute average concentrations over a 1 hour period at 100 m
animated gif image
Google Earth (kmz) output (optional)
Additional hints:
since the release rate required by HYSPLIT is per hour, you will need to multiply the unit emission rate by 4.
Check the Fix-Exp box to keep the contours constant in the animation
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PC-HYSPLIT WORKSHOP

9. Local Scale Dispersion Calculation
Use the Concentration setup / Pollutant, Deposition and Grids setup menu (upper right) to define a 15 minute (0.25h) release of one unit of mass. Note that since the release rate required by HYSPLIT is per hour, you will need to multiply the unit emission rate by 4 in this case.
Also, change the averaging period to 10 minutes over the 1 hour simulation, which can be defined in the Pollutant, Deposition and Grids Setup menu (lower right).
Run the model with SETUP
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PC-HYSPLIT WORKSHOP

10. Local Scale Dispersion Calculation
To create an animated GIF (right), keep the contours from changing as the concentrations decrease by checking Fix-Exp box and set the Contour drawing options to none in the Concentration Display menu to improve the display (however, if you want a Google Earth output this setting needs to be color or B & W).
Once the PostScript file has been created, you can create the animated GIF by checking the Animate box in the PostScript Conversion utility menu. This will create a file called concplot.gif in the /working directory.
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PC-HYSPLIT WORKSHOP

11. Local Scale Dispersion Calculation
Optionally, rerun the last simulation with a particle dump file and produce an particle position plot 1 hour after release. Also, try the Google Earth output of particles (still under development).
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PC-HYSPLIT WORKSHOP

12. Local Scale Dispersion Calculation
Particle Plot
Google Earth output (under development)
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