Fu, P., & Rich, P. M. (2002). A geometric solar radiation model with applications in agriculture and forestry. Computers and electronics in agriculture, 37(1), 25-35.
It is well known that sunlight is a necessary component of successful plant growth, along with water and nutrients. Few know that the temperature of the soil also has an effect on many biophysical processes. There is little information on how solar radiation actually affects the soil temperature and even less on how elevation affects the temperature of the soil. So in the study, Fu and Rich looked at a 300 km2 patch of land near the Rocky Mountain Biological Laboratory, in Colorado, USA. This area had varying elevations, which made it perfect for determining if elevation has any effect on the soil temperature. Before the start of the study, eleven soil temperature sensors were buried with which temperature readings were registered once an hour. However, only 7 of these sensors were fit to use at the end of the study.
After roughly a year, the sensors were retrieved and their information downloaded. With this information, as well as information gained from local weather stations, a map could be generated that showed the relative relationship between elevated areas and temperature of the soil. To achieve this, daily temperature values were averaged to create temperature ranges.
At the conclusion of the study, Fu and Rich discovered that a few variables led to errors in their data. For example, sensor placement had a small effect on the temperature recorded by the sensor. Additionally, the amount of vegetation cover above the sensor would obviously affect the temperature of the soil. And finally, the quality of the software that created the final maps had a few issues that could have led to inaccuracies in the maps. Overall, Fu and Rich found that the higher the elevation, the lower the temperature of the soil. They also determined that to have a more accurate map, far more sensors would have to be used. In this instance however, GIS created an adequate map that shows the relationship between the elevation of an area and the temperature of the soil.