Exploring impacts of size-dependent evaporation and entrainment in a global model

Among the suggested mechanisms for this discrepancy is the models' lack of connections between cloud droplet size and two processes that can contribute to reduced cloudiness when droplets become more numerous and smaller: evaporation and entrainment. In this study, we explore different implementations of size-dependent evaporation and entrainment in the global atmospheric model CAM5.3-Oslo.

We study their impact on the preindustrial-to-present day change in liquid water path (LWPPD-PI) and the corresponding aerosol indirect effect (AIE(PD-PI)). Impacts of the 2014-2015 fissure eruption in Holuhraun, Iceland, are also presented. Our entrainment modifications only have a moderate effect on AIE(PD-PI) (changes from -1.07 W m(-2) to -0.98 W m(-2)), and a small impact on the signal from the Holuhraun eruption compared to other suggested compensating mechanisms.