Instrument : Aethalometer (AETH)

Instrument Categories

Picture of the Aerosol Observing System

The aethalometer is an instrument that provides a real-time readout of the concentration of “black” or “elemental” carbon aerosol particles (BC or E) in an air stream. It is a self-contained instrument that measures the rate of change of optical transmission through a spot on a filter where aerosol is being continuously collected and uses the information to calculate the concentration of optically absorbing material in the sampled air stream. The instrument measures the transmitted light intensities through the “sensing” portion of the filter, on which the aerosol spot is being collected, and a “reference” portion of the filter as a check on the stability of the optical source. A mass flowmeter monitors the sample air flow rate. The data from these three measurements is used to determine the mean BC content of the air stream.

The aethalometer performs the optical analysis and data readout “on the spot.” The results are available immediately to the user without having to wait to analyze a sample at a laboratory. It is a self-contained, automatic instrument, and it requires no consumable materials, no gas cylinders, and no operator attention. The only calibration required is a periodic check of the air flowmeter response.

The AETH is part of the Aerosol Observing System (AOS).

Output Datastreams

Primary Measurements

The following measurements are those considered scientifically relevant.


North Slope Alaska
NSAX1 Browse DataExternal Data (satellites and others)
ARM Mobile Facility
ASIM1 Browse DataAscension Island, South Atlantic Ocean; AMF1
MAOS1 Browse DataManacapuru, Amazonas, Brazil; MAOS
PVCS1 Browse DataHighland Center, Cape Cod MA; MAOS retired
 retired = Originating instrument has been retired at this location

See Also


Cynthia Salwen
Brookhaven National Laboratory

Annette Koontz
Pacific Northwest National Laboratory
(509) 375-3609

Stephen Springston
Brookhaven National Laboratory
(631) 344-4477

Anne Jefferson
(303) 497-6493

Arthur Sedlacek
Brookhaven National Laboratory
(631) 344-2404