Understanding solar radiation analysis

Incoming solar radiation (insolation) received from the sun is the primary energy source that drives many of the earth's physical and biological processes. Understanding its importance to landscape scales is key to understanding a broad range of natural processes and human activities.

With landscape scales, topography is a major factor that determines the spatial variability of insolation. Variation in elevation, orientation (slope and aspect), and shadows cast by topographic features all affect the amount of insolation received at different locations. This variability also changes with time of day and time of year and in turn contributes to variability of microclimate including factors such as air and soil temperature regimes, evapotranspiration, snow melt patterns, soil moisture, and light available for photosynthesis.

The solar radiation analysis tools in the ArcGIS Spatial Analyst extension enable you to map and analyze the effects of the sun over a geographic area for specific time periods. It accounts for atmospheric effects, site latitude and elevation, steepness (slope) and compass direction (aspect), daily and seasonal shifts of the sun angle, and effects of shadows cast by surrounding topography. The resultant outputs can be easily integrated with other GIS data and can help model physical and biological processes as they are affected by the sun.