In this section we will examine the steps required to convert HYSPLIT output to the shapefile format compatible for input into a variety of GIS software products such as ArcExplorer or Map Window. Using GIS software, it is possible to overlay multiple products, such as trajectories, concentration plumes, meteorological data contours, and even point data, all on the same display. Alternative options are also available such as the GrADS (Grid Analysis and Display System). Software is provided in the \hysplit4\examples directory to convert output for display in GrADS.
- In the previous section, we had already computed the 1-hr average concentration pattern from 01-02 UTC on the 26th. Open the Concentration / Display / Concentration / Contours menu and set the ESRI Generate radio-button. Execute will open the display and also create two ASCII text files, GIS_01000_ps_00.txt (and .att), in generate format. The file name changes slightly according to the time period and output layer. The .txt file contains the contour polygon points and .att file contains optional attribute information.
- The next step is to convert the Generate format files to the binary shapefile format. Press the Utilities / GIS to Shapefile menu tab to open the conversion menu. Use the browse button to find the GIS text file then select the polygons radio-button for the conversion method (polygons are closed lines). Because an attributes file is available, select the concentration radio-button. Press Process Data and four output files will be created (concplot.shp .shx .dbf .prj) in the working directory. A system message will be displayed when the conversion is complete.
GIS software provides a powerful display tool that can be used to overlay a variety of different products on the same map. The sample shapefiles on the CD were all obtained from public sources.
These GIS programs are optional because several of the HYSPLIT graphical programs also have a rudimentary capability to display shapefiles and overlay multiple products which will be demonstrated in the next section.