Challenges and Solutions in Differentiating the Aerosol Effect from Others in Inducting Cloud Invigoration for Convective Clouds

The aerosol cloud invigoration refers to the enhancement of convection induced by aerosols through additional release of latent heat to fuel the vertical motion of clouds. The effect is further differentiated into mixed-phase cloud invigoration and warm-cloud invigoration accompanied by freezing of liquid cloud droplets and condensation of water vapor onto cloud droplets, or simply cold and warm invigoration effects, respectively. While the fundamental foundation of the invigoration theories are generally sound, there have been controversial viewpoints regarding the casual relationship between any aerosol/CCN proxy variables and the indices of the cloud invigoration effect due to complicated processes that are likely intertwined. Among others, they include co-variability between aerosol, atmospheric thermodynamics as described as the convective available potential energy (CAPE), and clouds that may be coupled or decoupled with the planetary boundary layer (PBL) hosting the bulk of aerosols. In this study, we will try to sort out such complex relationships to better single out the effect of aerosol in affecting convective clouds. To this end, we have analyzed ample observation data at high temporal resolution to allow for studying the effect in different phases of cloud development, as well as the evolutions of the PBL and its coupling with clouds. It is found that the CAPE is not a static external forcing factor but an internal variable subject to the influences of aerosol.