Air Concentration Utility Programs

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.


3. The ASCII conversion can also be performed at a single location by interpolating a value to a location. Select the Utilities / Grid 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. Set the Display Time Series radio-button to Yes. The units conversion should be set to 1.0E+12. Press Extract Data and the output file con2stn.txt will be created, but not opened in the GUI viewer. However, with the radio-button set, the time series plot will be displayed (timeplot.ps).


4. A variation of the interpolation to a location is the Utilities / Convert to DATEM tab which opens a similar options menu which converts the HYSPLIT output to the DATEM (Data Archive of Tracer Experiments and Meteorology) format by matching each value in the measurement file with a calculated value. First browse to find the measurement file: /Tutorial/captex/captex2_meas.txt. Then press Create DATEM file and the calculated data file hysplit.txt is created in the working directory. Pressing Compute Statistics analyzes the data and opens the GUI viewer to the results file: statA.txt. The scatter plot button opens a graphic showing the measured and calculated values identified by station number. The paired measured and calculated values are also written to the file: dataA.txt.

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, one of which is linked with some statistical analysis programs. The binary data manipulation programs available through the utilities menu tab will be discussed in other tutorial sections. Some supplemental exercises for this section are also available.