Abstract
Abstract. This study investigates the maintenance of cloud ice production in Arctic mixed-phase stratocumulus in large eddy simulations that include a prognostic ice nuclei (IN) formulation and a diurnal cycle. Balances derived from a mixed-layer model and phase analyses are used to provide insight into buffering mechanisms that maintain ice in these cloud systems. We find that, for the case under investigation, IN recycling through subcloud sublimation considerably prolongs ice production over a multi-day integration. This effective source of IN to the cloud dominates over mixing sources from above or below the cloud-driven mixed layer. Competing feedbacks between dynamical mixing and recycling are found to slow the rate of ice lost from the mixed layer when a diurnal cycle is simulated. The results of this study have important implications for maintaining phase partitioning of cloud ice and liquid that determine the radiative forcing of Arctic mixed-phase clouds.
Highlights
Reliable climate projections require realistic simulations of Arctic cloud feedbacks
In this study we focus on the internal microphysics and dynamics of the cloud-driven mixed layer by investigating processes in an Arctic mixed-phase stratocumuli (AMPS) decoupled from surface sources of moisture, heat, and ice nuclei
We have demonstrated that sustained recycling of ice nuclei (IN) through a drying subcloud layer and additional activation of NIN due to a cooling cloud layer are sufficient to maintain ice production and that these processes regulate liquid production over multiple days in a decoupled AMPS
Summary
Reliable climate projections require realistic simulations of Arctic cloud feedbacks. We posit that recycling plays a significant role more generally since, for example, assuming an adiabatic vertical profile, a 650 m deep mixed layer with a cloud-top temperature of −16 ◦C requires a water vapor mixing ratio of at least 1.7 g kg−1 at mixed-layer base to be saturated with respect to ice, i.e., in order for recycling to be a negligible source of ice nuclei in the mixed layer This value is typically only seen in the Arctic between May and September (Serreze et al, 2012), while persistent AMPS frequently occur outside of these months (Shupe et al, 2011). Within this modeling framework we investigate the relative roles of recycling and entrainment of IN in maintaining cloud ice production
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
