Evaluation of Aerosol Indirect Effects on Deep Convective Clouds in the Vicinity of the Sierras de Cordoba during CACTI

Aerosol indirect effects on deep convective clouds (DCCs) have been proposed to cause changes to cloud-top height, reflectivity profiles, and precipitation, among other such parameters. Despite numerous studies, there is much uncertainty in the effect of aerosols on DCCs due to issues with aerosol measurements, variability of such effects with the environment, and difficulties untangling meteorological effects from those of the aerosols.

The DOE/ARM Cloud, Aerosol, and Complex Terrain Interactions (CACTI) program in 2018-19 around the Sierras de Cordoba mountain range in Argentina produced concentrated surface, upper-air, radar, and aircraft observations in a location with a high frequency of convective initiation and resulting DCCs. The resulting data provide a unique opportunity to examine aerosol indirect effects on DCCs using observations in a rigorous and statistically sound manner.

We first use profiles from the 22 flights of the G-1 aircraft in combination with corresponding upper-air sounding data to identify the meteorological variables that best determine when aerosol concentrations measured at the surface are representative of those at cloud base. For periods throughout the 7-month CACTI period when surface measurements are representative of those at cloud base, we then use statistical analyses to identify the relationships that exist between (1) aerosol concentration, (2) meteorological variables, and (3) characteristics of DCCs. This analysis addresses many of the issues affecting prior studies of aerosol indirect effects, while also providing an analysis of the aerosol-DCC relationship in a region not previously studied.