Aerosol content of the atmosphere is an important factor in the propagation of high-energy laser (HEL) beams. Aerosol absorption leads to the thermal blooming effect, where the laser beam heats the air and thereby creates a diverging lens. We have used three methods to estimate the aerosol absorption coefficient: (1) a Mie calculation on experimentally determined size distributions, (2) the parametric Advanced Navy Aerosol Model (ANAM), and (3) the chemical transport model LOTOS-EUROS. Individual estimates of the absorption coefficient differ significantly, which in turn impacts greatly on the extent of thermal blooming and HEL-beam propagation. © 2019 SPIE.