Figure 8. Isomass maps (g/m2) of the August 19, 1992 Crater Peak/Spurr volcanic cloud as estimated from SSM/I data using the modified rain fall rate equation (top) and ground sampling of the ashfall blanket (bottom) [R. G. McGimsey, personal communication]. The diffence observed between the SSM/I data and the ground sampling data may be due to a wind shear. Note that the value of the 15000 contour line is only my estimate.