Journal Article

Aerosol-Cloud-Precipitation Interactions in a Closed-cell and Non-homogenous MBL Stratocumulus Cloud

Zheng, Xiaojian, Xi, Baike, Dong, Xiquan, Wang, Yuan, Wu, Peng, Ward, Dale M.

2022

Overview

A closed-cell marine stratocumulus case during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) aircraft field campaign is selected to examine the heterogeneities of cloud and drizzle microphysical properties and the aerosol-cloud-precipitation interactions. The spatial and vertical variabilities of cloud and drizzle microphysics are found in two different sets of flight legs: Leg-1 and Leg-2, which are parallel and perpendicular to the cloud propagation, respectively. The cloud along Leg-2 was close to adiabatic, where cloud-droplet effective radius and liquid water content linearly increase from cloud base to cloud top with less drizzle. The cloud along Leg-1 was sub-adiabatic with lower cloud-droplet number concentration and larger cloud-droplet effective, but higher drizzle droplet number concentration, larger drizzle droplet median diameter and drizzle liquid water content. The heavier drizzle frequency and intensity on Leg-1 were enhanced by the collision-coalescence processes within cloud due to strong turbulence. The sub-cloud precipitation rate on Leg-1 was significantly higher than that along Leg-2. As a result, the sub-cloud accumulation mode aerosols and CCN on Leg-1 were depleted, but the coarse model aerosols increased. This further leads to a counter-intuitive phenomenon that the CCN is less than cloud-droplet number concentration for Leg-1. The average CCN loss rates are −3.89 cm −3 h −1 and −0.77 cm −3 h −1 on Leg-1 and Leg-2, respectively. The cloud and drizzle heterogeneities inside the same stratocumulus can significantly alter the sub-cloud aerosols and CCN budget. Hence it should be treated with caution in the aircraft assessment of aerosol-cloud-precipitation interactions.

• Publisher: Science Press,Springer Nature B.V,Department of Hydrology and Atmospheric Sciences,University of Arizona,Tucson 85721,AZ,USA%Pacific Northwest National Laboratory,Richland 99354,WA,USA%Division of Geological and Planetary Sciences,California Institute of Technology,Pasadena 91125,CA,USA
• Subject: Adiabatic / Adiabatic flow / Aerosol-cloud interactions / Aerosols / Aircraft / Atmospheric Sciences / Cloud precipitation / Clouds / Coalescence / Diameters / Drizzle / Droplets / Earth and Environmental Science / Earth Sciences / Geophysics/Geodesy / Leg / Liquid water content / Meteorology / Microphysics / Moisture content / Original Paper / Precipitation / Precipitation rate / radiation / Stratocumulus clouds / their interactions / Turbulence / Water / Water content