## Concentration / Utilities / Grid to Station

The purpose of the Grid to Station utility menu (also called time series data extraction) is to list concentrations at specific latitude-longitude locations by extracting that information to a text file. The menu also has an option to produce a time series plot at one or more of the stations. An illustration of the menu is shown below. The concentration grid names are determined from the Concentration / Setup Run menu tabs and therefore needs to be configured first prior to opening this menu. The species and height values are index numbers starting at one. A height index of 1 is the data at the first output level, regardless of its actual height value. The date field can be written as a fractional Julian day (for plotting) or using a MM/DD/YYYY field (for spreadsheets) with or without an index record. The no index record option is used to concatenate multiple files.

Similar to the other menus in the utility section, the input concentration file must be defined in the Concentration Setup menu. The menu options correspond to the command line options of the con2stn extraction program. There are two options that can be used to define an extraction location. A station location can be defined directly as an entry in the menu, or a list of stations can be defined using an input file. If the input file does not exist, it can be created by using the New File button. In this example illustration, a file has been defined with three locations that are within the plume of the example simulation. The file consists of three records, one for each station:

The extraction program is called con2stn and for these three stations, produces the output file shown below, called by default con2stn.txt. In contrast to the simulation shown in all the previous examples, in this case the output averaging time was decreased from 12 hours to one hour, to generate a smoother looking graphic.

The output file shows the Julian day, month, day, and hour of the sample start; day and hour of sample ending time, and the concentrations for each station (location selected by latitude-longitude). The format of each output record is as follows:

F8.3, 6I4 - Starting: Julian day, year, month, day, hour; Ending: day, hour
XF10 - Concentration value at X stations

The lower section of the GUI is used to create a simple time series concentration plot of the concentration time series. One or more stations may be plotted and the option is also available through the command line. The option is selected from the Display Time Series checkbox. The program, timeplot, reads the data file produced by the con2stn conversion program and plots the concentration values to the timeplot.ps output file. The illustration for the previous text file is shown below.

There are only two plot options supported through the GUI: linear or logarithmic ordinate scaling. If integer ordinate units are desired then it may be necessary to specify a units conversion factor, in this case 1015, to create data in the text file that can be plotted. With the log scaling option, the conversion factor can be set to 1.0, and the ordinate scale will cover the appropriate order-of-magnitude range to plot all the data.

Command Line Options - con2stn

The program can be run from the command line or through interactive prompts from the keyboard. The command line argument syntax is that there should be no space between the switch and options. The command line arguments can appear in any order: con2stn -[option {value}]

-i [input concentration file name: (std input)]

Unspecified file names will result in a standard input prompt.

-o [output concentration file name: (std output)]
-c [input to output concentration multiplier: (1.0)]
-s [station list file name: (std input)]

The station positions can be read from a file (space or comma delimited) with the first field being an integer that represents the location identification, followed by the decimal location in latitude and longitude.

-x [(n)=neighbor or i for interpolation]

The default interpolation method (-xn) is to use the value at nearest grid point to each latitude-longitude position, otherwise bilinear interpolation (-xi) is used.

-r [record format output (default is column format)]

The default output format is to create multiple columns, one for each station, for a selected pollutant and level. Setting this option formats the output as one record for each station, level, and pollutant.

-z [level index (1) or 0 for all levels]
-p [pollutant index (1) or 0 for all pollutants]

Level and pollutant index values can be selected for files with multiple levels and species. Setting zero (0) for either index forces the output to be the record format rather than the column format. Record format contains the index numbers for the pollutant and level.

-m [maximum number of stations: 200]
-d [mm/dd/yyyy format: 0=no 1=With-Label 2=Without-Label]

The default date format is to write a fractional Julian date in the first output field. This format is required for plotting purposes. However, a more conventional month/day/year format can be selected, which is more compatible with spreadsheet applications. In the first option (=1) an informational header record is written. In the other option (=2) the header record is excluded, which is more convenient when appending multiple files.

Command Line Options - timeplot [option {value}]

-i[input concentration file name] contains data in the same format as output from con2stn
-m[minimum ordinate value (0.0)]
-n[sequential station number]

For files with multiple stations select the station to plot; default for multiple stations is to plot all stations; several stations can be selected to plot by appending station numbers with the plus symbol: hence -n3+5+6 will plot stations 3, 5, and 6.

-p[draw only points, no connecting line]
-y[The default is linear ordinate scaling. The flag sets y-axis log scaling.]
-z[three character time label]

Timeplot labels can also be customized by creating a LABELS.CFG file. See the concentration plotting discussion for more information on this file format.

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