On the suitability of the SRTM DEM for simulating potential insolation

Among many applications of Shuttle Radar Topography Mission (SRTM) and digital elevation model (DEM), the suitability of this data for simulating potential insolation (PI) has not been fully examined. This study examined the accuracy of potential insolation simulation based on 3 arc-second resolution SRTM. The National Elevation Dataset (NED) was used as reference data. Using a method which does not depend on control points, SRTM data was positionally matched to NED data. Then, we simulated potential insolation based on SRTM data and NED data. The results show that average absolute error of PI simulated based SRTM for equinox day, summer solstice day and winter solstice day accounts for 8.4%, 3.9% and 17.9% of corresponding SRTM PI respectively. This may restrict the applicability of SRTM PI to the researches and practices of high accuracy requirement. Overall, simulation based SRTM data can overestimate the potential insolation. Nonetheless, for areas without higher quality DEMs, the PI simulated based SRTM data is yet a rather valuable data for several applications. Both slope and aspect have significant impact on accuracy of PI simulation. While only a 1 °×1 ° area has been examined, we believe that our findings are basically applicable to other areas.