ISCST3 Tech Guide
6.5.2 Downwind, Crosswind and Radial Distances
The calculation of downwind and crosswind distances is described in Section 1.1.2. Since the complex terrain algorithms in ISC are based on a sector average, the radial distance is used in calculating the plume rise (see Section 1.5.4) and dispersion parameters (see Section 1.5.5). The radial distance is calculated as R = [x2 + y2]1/2, where x is the downwind distance and y is the crosswind distance described in Section 1.1.2.