HANDS-ON EXERCISES

4-1PC-HYSPLIT WORKSHOP

Part 4: Local scale dispersion calculation

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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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: 38.880N 77.027W 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: 0.001 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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Local Scale Dispersion Calculation

Click Reset from the main menuFrom 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 2009 (00 00 00 00),

To enter a vertical line source, enter 2 starting locations at the same lat/lon but at 2 different heights: 38.880N 77.027W @10m 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 0.001 degrees, and Grid Span of 1.0 degrees lat/lon.

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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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Local Scale Dispersion Calculation

After running the model, set the Concentration Display menu to the following:

Output File: concplotNumber of rings to 4 every 10 kmMap background to /working/map_county Zoom to 90% Dyn-Exp contoursTurn on the contour outlines (Color)  Turn on the Google Earth optionExecute Display

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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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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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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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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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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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Local Scale Dispersion Calculation

PC-HYSPLIT WORKSHOP

Particle Plot Google Earth output (under development)