Campaign : LASIC: Layered Atlantic Smoke Interactions with Clouds

2016.06.01 - 2017.10.31

Lead Scientist : Paquita Zuidema

For data sets, see below.

Abstract

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.

Other Contacts

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


Campaign Data Sets

IOP ParticipantData Source DescriptionFinal Data
SpringstonTrace Gases Order Data
WatsonProton Transfer Reaction Mass Spectrometer Order Data
SedlacekSingle Particle Soot Photometer Order Data
SpringstonParticle Soot Absorption Photometer Order Data

ARM Mobile Facility Instruments

Data Source DescriptionBrowse DataBrowse Plots
ACSM
Aerosol Chemical Speciation Monitor
 Browse Data Browse Plots
AERI
Atmospheric Emitted Radiance Interferometer
 Browse Data Browse Plots
AOS
Aerosol Observing System
 Browse Data
AOSMET
Meteorological Measurements associated with the Aerosol Observing System
 Browse Data Browse Plots
CCN
Cloud Condensation Nuclei Particle Counter
 Browse Data Browse Plots
CEIL
Ceilometer
 Browse Data Browse Plots
CPC
Condensation Particle Counter
 Browse Data
CSPHOT
Cimel Sunphotometer
 Browse Data
DL
Doppler Lidar
 Browse Data
ECOR
Eddy Correlation Flux Measurement System
 Browse Data Browse Plots
GNDRAD
Ground Radiometers on Stand for Upwelling Radiation
 Browse Data Browse Plots
HTDMA
Humidified Tandem Differential Mobility Analyzer
 Browse Data
IRT
Infrared Thermometer
 Browse Data Browse Plots
KASACR
Ka-Band Scanning ARM Cloud Radar
 Browse Data
KAZR
Ka ARM Zenith Radar
 Browse Data
LDIS
Laser Disdrometer
 Browse Data
MAWS
Automatic Weather Station
MET
Surface Meteorological Instrumentation
 Browse Data Browse Plots
MFR
Multifilter Radiometer
 Browse Data
MFRSR
Multifilter Rotating Shadowband Radiometer
 Browse Data Browse Plots
MPL
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
NEPHELOMETER
Nephelometer
 Browse Data Browse Plots
NFOV
Narrow Field of View Zenith Radiometer
OZONE
Ozone Monitor
 Browse Data
PASS
Photoacoustic Soot Spectrometer
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 Browse Plots
SKYRAD
Sky Radiometers on Stand for Downwelling Radiation
 Browse Data Browse Plots
SMPS
Scanning mobility particle sizer
 Browse Data Browse Plots
SO2
Sulfur Dioxide Monitor
 Browse Data
SODAR
Mini Sound Detection and Ranging
 Browse Data
SONDE
Balloon-Borne Sounding System
 Browse Data Browse Plots
SP2
Single Particle Soot Photometer
 Browse Data
TRACEGAS
Trace gas concentrations
 Browse Data
TSI
Total Sky Imager
 Browse Data Browse Plots
UHSAS
Ultra-High Sensitivity Aerosol Spectrometer
 Browse Data
WACR
W-Band (95 GHz) ARM Cloud Radar
 Browse Data
WSACR
W-band Scanning ARM Cloud Radar
 Browse Data
XSACR
X-Band Scanning ARM Cloud Radar