Clouds, Aerosols, and Precipitation in the Marine Boundary Layer: An Arm Mobile Facility Deployment

• Published in: Bulletin of the American Meteorological Society
• Main Authors: Wood, Robert, Wyant, Matthew, Bretherton, Christopher S., Rémillard, Jasmine, Kollias, Pavlos, Fletcher, Jennifer, Stemmler, Jayson, de Szoeke, Simone, Yuter, Sandra, Miller, Matthew, Mechem, David, Tselioudis, George, Chiu, J. Christine, Mann, Julian A. L., O’Connor, Ewan J., Hogan, Robin J., Dong, Xiquan, Miller, Mark, Ghate, Virendra, Jefferson, Anne, Min, Qilong, Minnis, Patrick, Palikonda, Rabindra, Albrecht, Bruce, Luke, Ed, Hannay, Cecile, Lin, Yanluan
• Language: unknown
• Published: 2021
• Subjects: 54 ENVIRONMENTAL SCIENCES; Northeast Atlantic
• Online Access: http://www.osti.gov/servlets/purl/1255441; https://www.osti.gov/biblio/1255441; https://doi.org/10.1175/BAMS-D-13-00180.1

The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) 38 deployment at Graciosa Island in the Azores generated a 21 month (April 2009-December 2010) 39 comprehensive dataset documenting clouds, aerosols and precipitation using the Atmospheric 40 Radiation Measurement (ARM) Mobile Facility (AMF). The scientific aim of the deployment is 41 to gain improved understanding of the interactions of clouds, aerosols and precipitation in the 42 marine boundary layer. 43 Graciosa Island straddles the boundary between the subtropics and midlatitudes in the 44 Northeast Atlantic Ocean, and consequently experiences a great diversity of meteorological and 45 cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulus and cumulus 46 occurring regularly. Approximately half of all clouds contained precipitation detectable as radar 47 echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1-48 11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide 49 range of aerosol conditions was sampled during the deployment consistent with the diversity of 50 sources as indicated by back trajectory analysis. Preliminary findings suggest important two-way 51 interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation 52 and cloud radiative properties while being controlled in part by precipitation scavenging. 53 The data from at Graciosa are being compared with short-range forecasts made a variety 54 of models. A pilot analysis with two climate and two weather forecast models shows that they 55 reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well, 56 but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to 57 be a long-term ARM site that became operational in October 2013.