8.3 Air Concentration Utilities




In this section we will review how the HYSPLIT binary air concentration file can be converted to other formats or interpolated to a sampling location. Statistical analysis programs are provided to compare the measured and calculated values. The previous section should have been completed before proceeding with this section.

  1. A quick listing of output file contents is obtained by pressing the Concentration / Utilities / Simple Listing menu tab. Use the Set File Name button to browse for the concentration file name hysplit2.bin and then press Show File Contents to open the file listing window, the GUI viewer of the output file conread.txt, which can be found in the /working directory. The listing shows the maximum and minimum concentrations each time period.

  2. A more complete listing is available through the Utilities / Convert to ASCII menu tab. The options menu provides several different format options to provide more spreadsheet import flexibility. For this example, set the Single File checkbox so that all time periods are in the same file rather than individual files. Also set the concentration units conversion to 1.0E+12 so that we get pg m-3 and then Execute Conversion. By default, the output file will always have the same name as the input file but with a .txt suffix: hysplit2.bin.txt. Concentration values for all non-zero grid points are listed. Try some other options to see the differences in the output format. The Force file name data entry option is a way to override the automatic file name selection based upon the entry in the Setup Run menu.

  3. The ASCII conversion can also be performed at a single location by interpolating a value to a location. Select the Utilities / Convert to Station menu tab to open the options menu. For this example we will select a location near the center of the CAPTEX sampling domain, station number 510, Little Valley, NY, south of Buffalo, near the Pennsylvania border. Enter the station ID C510 (C for calculated), and the location 42.25 -78.80. The units conversion should be set to 1.0E+12. Press the yellow Extract Data button and the output file con2stn.txt will be created and also opened in the GUI viewer. To plot the extracted data, press the green Plot Data button to display the time series shown in the output file timeplot.ps.

  4. With a little effort it is possible to overlay the measurements at station 510 with the model calculation. First make a copy of captex2_meas.txt from the /Tutorial/captex directory and rename it to captex2_m510.txt. Then open the file and delete all the measurements except those for station 510. Note that the model output is every 3h while the measurement data are every 6h. Therefore, each sample line in captex2_m510.txt must be divided into two lines representing two identical 3h measured values. When the changes are complete, enter captex2_m510.txt into the supplemental file field and press Plot Data to see the time series of both model calculation and measurements. Note that the plotting program is relatively simple and does not adjust multiple plots for time differences. Both files are required to have identical records. Only column and DATEM format files are supported.

There are several options that can be used to convert the HYSPLIT binary air concentration file to a text formatted file, each with several different formatting options. Binary data manipulation programs available through the utilities menu tab will be discussed in other tutorial sections.