Remote sensing is a useful tool for assessment of environmental conditions, either in an existing forest or prior to planting a new one. Data for climate analysis can be obtained through microwave or radar sensing, which is ideal for gathering information about the atmosphere, because, unlike photographic or video methods, it allows continuous observation regardless of light or weather conditions. This provides an uninterrupted flow of accurate data for interpretation, and long-term observations can be compiled to monitor climate changes. These data can be used to track rainfall and winds, as well as measure water and ozone content in the air. Analysis of the data can help determine the compatibility of the climate with forest growth, and predict potential problems.
Hydrology is another factor that is critical to forest growth.
Quantitative analysis of terrain, shown by aerial photography images, is another source of data for hydrological modeling. These analyses enable foresters to determine water availability and to predict droughts and flooding. GIS is a decision-making tool based on geographically referenced information. GIS uses different levels of geographical information, such as elevation, hydrology, or location of roads and infrastructure, to create a multi-layered representation of a site. Some remote sensing methods that are used in combination with GIS are aerial videography and Thematic Mapper sensing.