Cartographic Skills – Week 8 – Isarithmic Mapping

GIS 3015: Cartographic Skills

Week 8 Lab: Isarithmic Mapping

The Isarithmic maps below depict the 1981-2010 average annual precipitation for Washington State.  Isarithmic maps depict smooth, continuous phenomena across an area using varying symbology methods such as the continuous tone with hillshade effect and hypsometric tints with contours and hillshade effect shown below.  The data was measured at control points and then interpolated using the Parameter-elevation Relationships on Independent Slopes Model (PRISM). 

As precipitation generally increases with elevation, PRISM incorporates elevation into the surface by utilizing a digital elevation model (DEM).  PRISM has created substantially improved climate data by utilizing a relatively dense monitoring network with nearly 13,000 precipitation stations over the 48 conterminous states.