Atmospheric Radiation Measurement Climate Research Facility US Department of Energy

LASIC: Layered Atlantic Smoke Interactions with Clouds

1 June 2016 - 31 October 2017

Lead Scientist: Paquita Zuidema

Observatory: AMF, ASI

Southern Africa is the world's largest emitter of biomass-burning aerosols. Their westward transport over the remote southeast Atlantic Ocean colocates some of the largest atmospheric loadings of absorbing aerosol with the least examined of the Earth’s major subtropical stratocumulus decks. When the light-absorbing smoke is above a bright surface such as a low cloud deck, the net atmospheric absorption of sunlight increases, compared to a smoke-free environment. This constitutes a warming impact on climate. Because of the smoke, global aerosol models highlight that the largest positive direct radiative effect in the world occurs in the southeast Atlantic. Yet, this region also exhibits large differences in magnitude and sign between reputable models, partly because of differences in representing the underlying cloud distributions. In addition, some observations suggest positive direct radiative effects far exceeding those of global aerosol models.

Many uncertainties contribute to the highly variable model radiation fields for this region: the aging of the shortwave-absorbing aerosol during transport and how this affects the aerosol radiative properties, how much of the aerosol mixes into the cloudy boundary layer, and how the low clouds adjust to smoke-radiation and smoke-cloud interactions. LASIC (Layered Atlantic Smoke Interactions with Clouds) is a field campaign to improve understanding of aged carbonaceous aerosol and the mechanisms by which clouds adjust to the presence of the aerosol. The first ARM Mobile Facility's (AMF1) cloud, aerosol, and atmospheric profiling instrumentation is deployed to Ascension Island (8 degrees south latitude and 15 degrees west longitude), located within the trade-wind shallow cumulus regime 3,000 kilometers offshore continental Africa. This is within the latitude zone of the maximum outflow of aerosol, with the deepening boundary layer known to entrain free tropospheric smoke.

The primary activities for LASIC are to:

  • improve current knowledge on aged biomass-burning aerosol and its radiative properties
  • use surface-based remote sensing to sensitively examine the atmosphere for the relative vertical location of aerosol and clouds
  • improve understanding of the cloud adjustments to the presence of shortwave-absorbing aerosol within the vertical column, both through aerosol-radiation and aerosol-cloud interactions.

The measurements will span June 1, 2016, to October 31, 2017, which encompasses two biomass-burning seasons. LASIC contributes to an international, coordinated strategy focused on the southeast Atlantic. It will overlap with the National Aeronautics and Space Administration (NASA) ORACLES-2016 and U.K. CLARIFY aircraft campaigns from August to September 2016, and the NASA ORACLES-2017 and National Science Foundation ONFIRE aircraft campaigns in 2017 (see Related Campaigns link). St. Helena Island (15 degrees south latitude and 5 degrees west longitude), located upwind of Ascension within the boundary layer flow and directly west of the main stratocumulus deck, will receive modest secondary instrumentation as part of CLARIFY, LASIC, and NASA.

Smoke and clouds over the remote ocean represent a regime of significant climatic importance that has not yet been examined with comprehensive surface-based measurements. Ascension Island is strategically located to collect observations with which to resolve current uncertainties in the aging and transport of smoke and its interactions with low clouds. These processes control the spatial and vertical distribution of the Earth's radiative balance at a location with important cloud feedbacks to climate. The long-term, high-time-resolution measurements from an AMF1 deployment provide a stringent test for global aerosol models.

Co-Investigators

Matt Alvarado Jim Haywood David Romps
J.-Y. Christine Chiu Pavlos Kollias David Turner
Simon de Szoeke Ernie Lewis Hailong Wang
Chris Fairall Allison McComiskey Robert Wood
Graham Feingold David Mechem Sandra Yuter
Steven Ghan Jens Redemann Ping Zhu

Related Publications

2016

Zuidema P, J Redemann, J Haywood, R Wood, S Piketh, M Hipondoka, and P Formenti. 2016. "Smoke and Clouds above the Southeast Atlantic: Upcoming Field Campaigns Probe Absorbing Aerosol’s Impact on Climate." Bulletin of the American Meteorological Society, 97(7), 10.1175/bams-d-15-00082.1.


View All Related Publications

Campaign Data Sets

IOP Participant Data Source Name Final Data
Arthur Sedlacek Single Particle Soot Photometer Order Data
Stephen Springston Particle Soot Absorption Photometer Order Data
Stephen Springston Trace Gases Order Data
Thomas Watson Proton Transfer Reaction Mass Spectrometer Order Data

ASI Data Sources

Name Full Name Browse Data
ACSM Aerosol Chemical Speciation Monitor Browse Data
AERI Atmospheric Emitted Radiance Interferometer Browse Data
AETH Aethalometer Browse Data
AOD Aerosol Optical Depth, derived from atmospheric extinction of solar irradiance Browse Data
AOS Aerosol Observing System Browse Data
AOSMET Meteorological Measurements associated with the Aerosol Observing System Browse Data
CCN Cloud Condensation Nuclei Particle Counter Browse Data
CEIL Ceilometer Browse Data
CO-ANALYZER Carbon Monoxide Analyzer Browse Data
CPC Condensation Particle Counter Browse Data
CSPHOT Cimel Sunphotometer Browse Data
DL Doppler Lidar Browse Data
DLPROF Doppler Lidar Profiles Browse Data
ECMWFDIAG European Centre for Medium Range Weather Forecasts Diagnostic Analyses Browse Data
ECOR Eddy Correlation Flux Measurement System Browse Data
GNDRAD Ground Radiometers on Stand for Upwelling Radiation Browse Data
HTDMA Humidified Tandem Differential Mobility Analyzer Browse Data
INTERPSONDE Interpolated Sonde Browse Data
IRT Infrared Thermometer Browse Data
KASACR Ka-Band Scanning ARM Cloud Radar Browse Data
KAZR Ka ARM Zenith Radar Browse Data
LDIS Laser Disdrometer Browse Data
MET Surface Meteorological Instrumentation Browse Data
MFR Multifilter Radiometer Browse Data
MFRSR Multifilter Rotating Shadowband Radiometer Browse Data
MPL Micropulse Lidar Browse Data
MPLCMASK Cloud mask from Micropulse Lidar Browse Data
MWR Microwave Radiometer Browse Data
MWR3C Microwave Radiometer, 3 Channel Browse Data
MWRHF Microwave Radiometer - High Frequency Browse Data
MWRP Microwave Radiometer Profiler Browse Data
MWRRET MWR Retrievals Browse Data
NEPHELOMETER Nephelometer Browse Data
NFOV Narrow Field of View Zenith Radiometer Browse Data
NOX Nitrogen Oxides Monitor Browse Data
OZONE Ozone Monitor Browse Data
PBLHT Planetary Boundary Layer Height Browse Data
PSAP Particle Soot Absorption Photometer Browse Data
RAIN Rain Gauge Browse Data
RWP Radar Wind Profiler Browse Data
SASHE Shortwave Array Spectroradiometer-Hemispheric Browse Data
SASZE Shortwave Array Spectroradiometer-Zenith Browse Data
SEBS Surface Energy Balance System Browse Data
SKYRAD Sky Radiometers on Stand for Downwelling Radiation Browse Data
SMPS Scanning mobility particle sizer Browse Data
SO2 Sulfur Dioxide Monitor Browse Data
SODAR Mini Sound Detection and Ranging Browse Data
SONDE Balloon-Borne Sounding System Browse Data
SONDEGRID Gridded Sonde VAP Product Browse Data
SP2 Single Particle Soot Photometer Browse Data
TSI Total Sky Imager Browse Data
UHSAS Ultra-High Sensitivity Aerosol Spectrometer Browse Data
VISST Minnis Cloud Products Using Visst Algorithm Browse Data
WACR W-Band (95 GHz) ARM Cloud Radar Browse Data
WB Weighing Bucket Precipitation Gauge Browse Data
WSACR W-band Scanning ARM Cloud Radar Browse Data