| Keith T. Weber |
| Author is the GIS Director, Idaho State University - GIS Training and Research Center, Campus Box 8130, Pocatello, Ida. 83209-8130. Manuscript accepted: April 15, 2000 |
| Full text article |
Abstract |
| Land cover change analysis is an important and common image processing technique. Normally, change analysis is performed between 2 images that have been matched by calendar date instead of using some form of environmental criterion. Under this scenario, detected changes may only reveal differences in phenology and not real differences in vegetative land cover trends. Two primary factors influence the phenology of the environmental year. These are growing degree-days (GDD) and accumulated precipitation (AP). Other factors are important as well (e.g., humidity, wind, the rate and form of accumulated precipitation, and the precipitation regime from recent years), but growing degree-days and accumulated precipitation appear to be the best correlates with phenology. The potential errors and biases associated with this model are discussed. The author developed a software program (Pheno-Calc) that allows the user to calculate GDD and AP, graph and view the data set, and perform match calculations. Match calculations allow the user to more strategically choose remotely sensed imagery for analysis of land cover change by providing the dates on which GDD and/or precipitation accumulation has been matched. |
| Key Words: remote sensing, GIS |