Concentration / Display / Time-of-Arrival

Time of arrival graphic (isochron) shows the time after the start of the simulation that the concentration exceeds the given threshold concentration at each concentration grid cell. The default contour interval (-1) uses the concentration averaging period. Otherwise, the time difference field should be set to hours. A text label with release information may be printed below the threshold through the LABELS.CFG file.

The GUI and the command line options are similar with the command line syntax as follows: USAGE: isochron -[options(default)]

-c[color fill no:0 yes:(1)] : the =0 option results in contours
-d[difference in hours between contours (-1)]
-f[frames: (0)-all frames one file, 1-one frame per file] : multiple frames can only be due to multiple levels or species in the input file
+g[graphics type: (0)-Postscript 1-SVG]
-i[input file name (cdump)] : the input file needs to contain multiple time period
-j[graphics map background file (arlmap)] : the shape file option is not available
-n[number of contours (12)] : only 12 contours fit across the display
-o[output name (toa)] : the output file represents all time periods
-p[Process file name suffix: (ps) or process ID] -t[threshold value (1.0E-36)]

In the 144 hour duration example simulation shown below, the concentration field was output every six hours, the contour interval was set to 12 hours, and the threshold to 0.1E-15 . The one hour duration release took about 72 h to reach Hudson's Bay and about 144 h to reach into the Atlantic off the east coast of the U.S.