Aerosol scavenging rates derived from dual linear polarization reflectivity measurements

Precipitation scavenging dominates the aerosol removal processes from the atmosphere and has been estimated to be responsible for as much as 80% of total aerosol removal. Accurate estimation of the interaction of rainfall and aerosols is particularly important because of effects on visibility, damage to property and materials and human health and welfare. It also has an impact on climatic studies because of aerosol effects on the Earth´s radiation budget. The paper demonstrates the potential use of radar dual linear polarization measurements for estimating the scavenging coefficient for the below cloud processes of washout due to raindrop scavenging interactions with aerosols during their fall through the atmosphere. Essentially, the information contained in the polarimetric radar measurements (Z_H, Z_DR) appears sufficient to account for this dependence. Simulations of this methodology are presented based on relationships derived from disdrometer measurements of rainfall. Excellent estimates of particle scavenging rates Λ can be obtained compared to rates derived from reflectivity factor Z_H or rainfall rate R alone. The results demonstrate that dual linear polarization radar measurements can provide effective means for monitoring aerosol washout from the atmosphere