Atmospheric Radiation Measurement Climate Research Facility US Department of Energy

Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA)

1 June 2017 - 28 February 2018

Lead Scientist: Jian Wang

Observatory: aaf, ena

With their extensive coverage, low clouds greatly influence global climate, but they are poorly represented in global climate models (GCMs). The response of low clouds to changes in atmospheric greenhouse gases and aerosols remains the major source of uncertainty in climate simulations. The poor representations of low clouds in GCMs are partly due to inadequate observations of their microphysical and macrophysical structures, radiative effects, and the associated aerosol distribution and budget in regions where the aerosol impact is the greatest. The Eastern North Atlantic (ENA) is a region with persistent but diverse subtropical marine boundary layer (MBL) clouds. Their albedo and precipitation are highly susceptible to perturbations in aerosol properties. Boundary layer aerosol in the ENA region is influenced by a variety of sources, leading to strong variations in cloud condensation nuclei (CCN) concentration and aerosol optical properties. The ARM Climate Research Facility has a fixed ENA atmospheric observatory on Graciosa Island in the Azores, providing invaluable information on MBL aerosols and low clouds. At the same time, the vertical structures and horizontal variabilities of aerosols, trace gases, clouds, drizzle, and atmospheric thermodynamics are critically needed for understanding and quantifying the budget of MBL aerosols, the radiative properties, precipitation efficiency, and life cycle of MBL clouds, and the cloud response to aerosol perturbations. Much of this data can be obtained only through aircraft-based measurements. In addition, the interconnected aerosol and cloud processes are best investigated by a study involving simultaneous in situ aerosol, cloud, and thermodynamic measurements. In situ measurements are also necessary for validating and improving ground-based retrieval algorithms at the ENA observatory. The Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) field campaign was motivated by the need for comprehensive in situ characterizations of boundary layer structure, and associated vertical distributions and horizontal variabilities of low clouds and aerosols over the Azores. The ARM Aerial Facility (AAF) Gulfstream-159 (G-1) research aircraft flew from Terceira Island in the Azores during two intensive operational periods: early summer 2017 (June to July) and winter 2018 (January to February). Deployments during both seasons allowed for examination of key aerosol and cloud processes under a variety of representative meteorological and cloud conditions. The science themes for ACE-ENA included:

  • the budget of MBL CCN and its seasonal variation
  • effects of aerosols on clouds and precipitation
  • cloud microphysical and macrophysical structures, and entrainment mixing
  • advancing retrievals of turbulence, clouds, and drizzle
  • model evaluation and process studies.

A key advantage of the deployments is the strong synergy between the measurements aboard the G-1 and the routine measurements at the ENA observatory, including state-of-the-art profiling and scanning radars. The three-dimensional cloud structures provided by the scanning radars will put the detailed in situ measurements into mesoscale and cloud life cycle contexts. On the other hand, high-quality in situ measurements will enable validation and improvements of ground-based retrieval algorithms at the ENA observatory, leading to high-quality and statistically robust data sets from the routine measurements. The deployments, combined with the routine measurements at the ENA site, will have a long-lasting impact on the research and modeling of low clouds and aerosols in the remote marine environment. Operational Periods: --2017.06.01-2017.07.31 --2018.01.01-2018.02.28


Eduardo Azevedo Mary Gilles Edward Luke
Christopher Bretherton Anne Jefferson Allison McComiskey
Duli Chand Michael Jensen Fan Mei
J.-Y. Christine Chiu Pavlos Kollias Mark Miller
Xiquan Dong Chongai Kuang Arthur Sedlacek
Jerome Fast Alexander Laskin Raymond Shaw
Andrew Gettelman Ernie Lewis Robert Wood
Steven Ghan Xiaohong Liu
Scott Giangrande Yangang Liu


  • Child Campaign


Christensen M, P Wu, A Varble, H Xiao, and J Fast. 2024. "Aerosol-induced closure of marine cloud cells: enhanced effects in the presence of precipitation." Atmospheric Chemistry and Physics, 24(11), 10.5194/acp-24-6455-2024.

Mccoy I, M Wyant, P Blossey, C Bretherton, and R Wood. 2024. "Aitken Mode Aerosols Buffer Decoupled Mid‐Latitude Boundary Layer Clouds Against Precipitation Depletion." Journal of Geophysical Research: Atmospheres, 129(12), E2023JD039572, 10.1029/2023JD039572.
Research Highlight

van Leeuwen P, JC Chiu, and CK Young. 2024. "Uncertainty quantification for deep learning." arXiv, , 10.48550/arXiv.2405.20550.

Wilbourn E, L Lacher, C Guerrero, H Vepuri, K Höhler, J Nadolny, A Pantoya, O Möhler, and N Hiranuma. 2024. "Measurement report: A comparison of ground-level ice-nucleating-particle abundance and aerosol properties during autumn at contrasting marine and terrestrial locations." Atmospheric Chemistry and Physics, 24(9), 10.5194/acp-24-5433-2024.

Allwayin N, M Larsen, S Glienke, and R Shaw. 2024. "Locally narrow droplet size distributions are ubiquitous in stratocumulus clouds." Science, 384(6695), 10.1126/science.adi5550.
Research Highlight

Mei F and K Gaustad. 2024. ARM Aerial Facility (AAF) Merged Value-Added Product Report for Historical G-1 Field Campaigns. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-TR-299. 10.2172/2335708.

Nie Y, X Li, Q Paletta, M Aragon, A Scott, and A Brandt. 2024. "Open-source sky image datasets for solar forecasting with deep learning: A comprehensive survey." Renewable and Sustainable Energy Reviews, 189, 113977, 10.1016/j.rser.2023.113977.


Zhang D, A Vogelmann, F Yang, E Luke, P Kollias, Z Wang, P Wu, W Gustafson Jr., F Mei, S Glienke, J Tomlinson, and N Desai. 2023. "Evaluation of four ground-based retrievals of cloud droplet number concentration in marine stratocumulus with aircraft in situ measurements." Atmospheric Measurement Techniques, 16(23), 10.5194/amt-16-5827-2023.

Tang S, A Varble, J Fast, K Zhang, P Wu, X Dong, F Mei, M Pekour, J Hardin, and P Ma. 2023. "Earth System Model Aerosol–Cloud Diagnostics (ESMAC Diags) package, version 2: assessing aerosols, clouds, and aerosol–cloud interactions via field campaign and long-term observations." Geoscientific Model Development, 16(21), 10.5194/gmd-16-6355-2023.

Ghate V, T Surleta, L Magaritz‐Ronen, S Raveh‐Rubin, F Gallo, A Carlton, and E Azevedo. 2023. "Drivers of Cloud Condensation Nuclei in the Eastern North Atlantic as Observed at the ARM Site." Journal of Geophysical Research: Atmospheres, 128(22), e2023JD038636, 10.1029/2023JD038636.
Research Highlight

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Campaign Data Sets

IOP Participant Data Source Name Final Data
Alexander Laskin Time Resolved Aerosol Collectors Order Data
Chuck Long Radiometer Suite (Tilt Corrected Data) Order Data
Alyssa Matthews Ambient Winds- AIMMS Order Data
Alyssa Matthews G-1 Order Data
Alyssa Matthews High Volume Precipitation Spectrometer - Images Order Data
Alyssa Matthews Water Content Monitor Order Data
Fan Mei 2DS Particle Imaging Probe Order Data
Fan Mei Condensation Particle Counter Order Data
Fan Mei Fast Cloud Droplet Probe (FCDP) Order Data
Fan Mei High Volume Precip Spectrometer Order Data
Fan Mei Merged-2dsfcdphvps Order Data
Fan Mei meteorology/state/position parameters Order Data
Mikhail Pekour Aerodynamic Part Sizer Order Data
Mikhail Pekour Aerosol Size Distribution Best Estimate by airborne measurements Order Data
Mikhail Pekour Open Path Tunable Diode Laser Hygrometer Order Data
Mikhail Pekour Optical Particle Counter - Counterflow Virtual Impactor Order Data
Mikhail Pekour Optical Particle Counter - Isokinetic Order Data
Raymond Shaw Holographic Detector for Clouds Order Data
John Shilling High- Resolution Time-of-Flight Aerosol Mass Spectrometer Order Data
John Shilling Proton Transfer Reaction Mass Spectrometer Order Data
Stephen Springston Carbon Monoxide Analyzer aboard Aircraft_IOPI Order Data
Stephen Springston Carbon Monoxide Analyzer aboard Aircraft_IOPII Order Data
Stephen Springston Ozone Monitor aboard Aircraft_IOPI Order Data
Stephen Springston Ozone Monitor aboard Aircraft_IOPII Order Data
Amy Sullivan Particle-Into-Liquid Sampler (PILS) Order Data
Jason Tomlinson Cloud Aerosol Precip Spectrometer(CAPS)/Cloud Imaging Probe (CIP) Order Data
Jason Tomlinson Cloud and Aerosol Spectrometer Order Data
Jason Tomlinson Liquid Water Content (pvm-100a probe, SEA WCM-2000) Order Data
Jason Tomlinson Passive Cavity Aerosol Spectrometer Order Data
Janek Uin Aerosol Monitoring System- Ground Order Data
Janek Uin Ultra-High Sensitivity Aerosol Spectrometer Order Data
Jian Wang Fast Integrated Mobility Spectrometer Order Data
Jian Wang Nano-Scanning Mobility Particle Sizer (SMPS) Order Data
Jian Wang Scanning Mobility Particle Sizer Order Data