This week’s lab is working with raster data and mapping the annual rainfall in Washington state with the end result of an Isarithmic map. These are maps of continuous data presented smoothly across a geographic region or area. They are primarily used for temperature or precipitation.
I used hypsometric tinting and a continuous tone to display the data. In ArcGIS, the analysis tool used was INT and Dynamic Range Adjustment for the raster layer to adjust color shading for better visibility. The data were classified into 10 classes with a default color scheme for precipitation. After adding all of the data to the map contours were added which aided in understanding the rainfall amounts if one is familiar with the topography of Washington.
Oregon State University created the data we used for this lab using an analytical method called PRISM, Parameter-elevation Regressions on Independent Slopes Model. According to the National Geospatial Center of Excellence, “PRISM is an analytical model that uses point data and a digital elevation model (DEM) to generate gridded estimates of annual, monthly, and event-based climatic parameters.” The data was taken over a 30-year span from 1981-2010. It opened the door to a better way of studying and observing precipitation data.
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