M6 - Isarithmic Mapping

 

Hypsometric Tint Map of Annual Precipitation Levels in Washington State

This week's module involved constructing an isarithmic map. This map was to display annual precipitation levels across the state of Washington over a 30 year period. The precipitation data was downloaded from the USDA Geospatial Data Gateway and the dataset was created by the PRISM group at Oregon State University. This raw data was then interpolated using the PRISM method. This method uses point data and an underlying grid (such as a Digital Elevation Model or DEM) to create gridded estimates of the precipitation values in between known points. The PRISM method is unlike many others in that it accounts for outside factors such as terrain and elevation into its algorithm when assigning symbology to values. 

I divided the classes up using the quantile method and then adjusted the symbology and class labels accordingly. To help emphasize known terrain in the state of Washington, I used the 'Int' spatial analyst tool to create a hillshade of varying shades of purple. Then I adjusted the transparencies of the selected color scheme points which allows it to show (but not too greatly) in the background of the map. I also used the Contour List spatial analyst tool to add contour lines at each of the precipitation level boundaries to emphasize the devision between classes. To construct the legend, I removed the space between legend items to showcase the transition from red to purple of the Precipitation color scheme. 

Overall, I greatly enjoyed learning how to construct an isarithmic map and find them to be very aesthetically pleasing. I think they are extremely useful for mapping atmospheric/climactic conditions such as temperatures, precipitation, wind patterns, and so forth. I also had great success in this lab and encountered much faster server speeds and better responsiveness after the UWF IT department conducted a hard reset on my student account.