Module at Isarithmic Mapping - Come on in the weather is fine....as are the hills, valleys, depressions...

                This week we learned about Isarithmic Mapping.  Within that scope, we were introduced to various methods of interpolation, including PRISM, worked with continuous raster data and learned how to symbolize and produce a complete and accurate legend.  We worked with both continuous tone and hypsometric symbology both utilizing hillshade relief.  Additionally we learned to create contours to overlay on our hypsometric symboloized map.  The map illustrated here was our final product and depicted the annual precipitation for the State of Washington using climate data from 1981-2010.  The Prism method interpolated the data using the 30 year precipitation data and a DEM of the state for elevations.  The various algorithms take location, elevation, coastal proximity, topographic orientation, vertical atmospheric layer, topographic position and orthographic effectiveness of the terrain in relation to the monitoring locations (stations), to develop a suitable model for our map.  We used the Integer Spatial Analyst tool to convert the floating raster values to integers so that we could create “crisp” contours and be able to truncate values as whole numbers.  Renaming the layer to something less cryptic later facilitated making the legend more functional.  We classed the data using a manual break method with 10 breaks (break values were provided within the lab).  After classing the data, we chose a precipitation color ramp and applied a hillshade effect.  This produced an attractive map with visible relief.  In order to make the relief even more visible, our next task was to add contour lines.  This was accomplished using the Contour List Spatial Analyst tool.  We assigned contour values which matched our break values.  Although one would typically notate the contour interval in the legend, this step was unnecessary in this case since our contours followed our hypsometric steps.  I symbolized the contours using the temperature contour line available within the weather style manager.  The final steps were to add essential map elements to create a finished, easy to understand, visually appealing map.