Observed impacts of aerosol concentration on maritime tropical convection within constrained environments using airborne radiometer, radar, lidar, and dropsondes

Abstract. Aerosol modulation of atmospheric convection remains an important topic in ongoing research. A key challenge in evaluating aerosol impacts on cumulus convection is isolating their effects from environmental influences. This work investigates aerosol effects on maritime tropical convection using airborne observations from NASA's Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP²Ex). Nine environmental parameters with known physical connections to cloud and storm formation were identified from dropsonde data, and 144 dropsondes were matched with corresponding CAMP²Ex flight segments ("scenes"). To constrain environmental conditions, scenes were binned based on their association with "low", "medium", or "high" values for each dropsonde-derived parameter. In each scene and environmental bin, eight radar- and radiometer-based parameters directly related to convective intensity and/or frequency were correlated with lidar-derived aerosol concentrations to examine trends in convective characteristics under different aerosol conditions. Threshold values used to stratify the environments were varied across four sensitivity tests. Convective parameters and aerosol concentrations typically became more strongly and positively correlated, with statistical significance, as environmental conditions became more favorable for convection. Particularly strong correlations between convective and aerosol metrics resulted from stratifying environments based on their 850–500-hPa temperature lapse rate (LR), 700–500-hPa LR, and K-Index. While general trends suggested that higher aerosol concentrations were correlated with stronger and/or more-frequent convection, some cases saw a "Goldilocks" zone of medium aerosol concentration favoring enhanced convection. These results indicate that medium-to-high aerosol concentrations may enhance convection, but also stress the importance of considering environmental conditions when evaluating aerosol impacts.