Clouds, aerosols, and precipitation in the marine boundary layer: An arm mobile facility deployment

A 21-month deployment to Graciosa Island in the northeastern Atlantic Ocean is providing an unprecedented record of the clouds, aerosols, and meteorology in a poorly sampled remote marine environment. (CAP-MBL). CAP-MBL was designed to gather an extended record of high-quality data on clouds and aerosol properties in a remote marine environment needed to improve the treatment of clouds and aerosols in climate models. A feature of the CAP-MBL deployment is the ability to simultaneously observe clouds, aerosols, and precipitation and to understand how these variables interact with each other. Interactions are two way, with aerosols potentially impacting precipitation most likely via the suppression of warm rain but in turn aerosols are strongly scavenged by precipitation, even in the relatively weak drizzle from low clouds. The CAP-MBL deployment's continuous record allows for greater statistical reliability in the observed relationships between aerosols, clouds, and precipitation than is possible with aircraft but retains the advantages of in situ sampling of aerosol properties that are difficult to constrain with satellite data. Given the great variety of aerosol, cloud, and precipitation conditions, the data from CAP-MBL and from the permanent site will continue to challenge understanding and provide an unprecedented dataset for the evaluation and improvement of numerical models from cloud-resolving ones to global weather and climate models.