Impact of condensation upon LIDAR observables from aluminized solid propellant rocket contrails

Lidar has been used to track the downwind dispersion of rocket launch contrails and also to determine the particle size distribution of the primary Al₂O₃ smoke particles in the contrail. However, the determination of primary particle size from such lidar measurements is complicated by the presence of secondary smoke in the contrail composed of aqueous hydrochloric acid droplets. In addition, the secondary smoke tends to condense upon the Al₂O₃ primary smoke particles in the form of a liquid coating, with the primary smoke particles acting as condensation nuclei. The potential effect of this liquid coating upon the lidar backscatter return from the rocket contrail is estimated using a standard light scattering model (BHCOAT) for two-zone core-mantle particles.