Solar radiation is an important natural phenomenon that impacts many aspects of the environment and human life. The ability to model this radiation accurately is crucial in numerous fields, including agriculture, ecology, engineering, and forestry.
In their article, Dubayah and Rich seek to understand the performance of GIS when used as a tool to model solar radiation on the Earth’s surface. Several different factors influence solar radiation at a particular point on the Earth: topography, illumination angle, obstruction of the sky by nearby terrain, and reflectance of radiation by surrounding terrain. Dubayah and Rich argue that all of these factors can be modeled in a GIS to create a “sophisticated” solar radiation model. In their research, they evaluate two different GIS models currently used by scientists: ATM and SOLARFLUX. ATM is a raster-based model focused on atmospheric radiation that can “generate detailed topoclimatologies for large areas at arbitrary time intervals.” SOLARFLUX uses input of elevation, latitude, and atmospheric conditions to calculate the level and duration of direct radiation to each point.
Both of these models are useful, especially when used in tandem, but Dubayah and Rich emphasize there are still many problems to be solved if GIS is to improve its radiation modeling capabilities. These problems include better integration with other programs, the need for basic solar radiation modeling in new versions of software, and the capability to model clouds (which greatly affect radiation). They also comment on the problem of significant errors in public digital elevation data. As calculations based on this data are performed, this error propagates, potentially leading to inaccurate conclusions. Despite these future challenges, Dubayah and Rich conclude that GIS has the potential to “provide the ideal modeling environment for … solar radiation models.”
Dubayah, R., & Rich, P. M. (1995). Topographic solar radiation models for GIS. International Journal of Geographical Information Systems, 9(4), 405-419.
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Simone Yoxall
This is cool! The potential applications of these models are endless: they could be used for finding locations for solar panels or rooftop gardens, or for measuring potential agricultural areas. As you mentioned, this sort of model would be most useful if it included or was used in tandem with a model for precipitation, cloud cover, foliage type, et cetera, but it is still a very useful tool.
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