# Exercise #9

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• Problem #1 - The 914 m AGL flight data file contained results from a sampling pass about 2 hours earlier (around 0100 on 26 September) than the one used in the previous examples. Would the base case simulation result be similar using these sampling data?

• Hint - Retrieve conc_case_control.txt and conc_case_setup.txt and reconfigure the simulation for a sampling time between 0100-0200. Create your own measured data file with the appropriate start times or use the one provided: data_case0.txt.

• Solution - How are these earlier aircraft results different from the original example collected two hours later?

• Problem #2 - Again retrieve conc_case_control.txt and conc_case_setup.txt to run the original example but this time configure the simulation to determine the concentration profile at the location of measurement maximum (rounding to 0.05 degrees: 41.1, -82.5).

• Hint - Configure the simulation for 10 levels at 250 m intervals.

• Solution - Use the concentration display to show the contours at each level. Comparing the results for the two lowest layers (250 m and 500 m MSL), why does the lowest layer show a much smaller plume? Another way to extract the concentration profile is to use the utility convert to ASCII. Open the output file (hysplit2.bin.txt) to find the grid point nearest to the maximum measured concentration The profile shows that the maximum occurred between 500-750 m MSL.