terrain complexe

CONT: Models for the assessment of environmental impacts of air pollutants released in the vicinity of hills or mountains differ somewhat from the normal bi-Gaussian plume formula. Furthermore, there are two specific concerns associated with the release and transport of atmospheric pollutants in an area with complex terrain. First, the impingement of plumes on elevated terrain surfaces may result in dangerously high ground-level concentrations. Second, there is the possibility of unusually long periods of stagnation within the atmospheric boundary layer in lower, valley-like regions.