Aerosol and thermodynamic controls on tropical cloud systems during TWPICE and ACTIVE

The Darwin ARCs and the surrounding areas sample strongly forced diurnal convective storms in the non-monsoon periods of the wet season. In particular, a set of thunderstorms form almost every day on the islands just to the north of Darwin. This represents an opportunity to use these systems as a natural laboratory to study the impact of the distinct seasonal cycle of aerosols and thermodynamic environment. The aerosol loading in the boundary layer has high aerosol concentrations associated with biomass burning in the early part of the season. There is a weaker, but still significant seasonal variations in thermodynamic characteristics through the season that is independent of the aerosol variations. During the 2005 and 2006 intensive observing periods of UK ACTIVE (Aerosol and Chemical Transport In tropical conVEction) and ARM/Bureau TWPICE experiments, the UK Dornier aircraft was making detailed aerosol observations. These are used to define aerosol regimes and the statistical characteristics of the storm systems are examined. These observations are combined with radar and satellite derived products describing active convective areas, cloud areas, and differences in microphysical structure for the cloud systems. Preliminary analysis of the observations shows almost no dependence on the aerosol regime. However, there is a small signal associated with the average CAPE values from Darwin soundings. High resolution modelling supporting this work suggests a complex interplay of aerosol and thermodynamic effects.