MAGEE SCIENTIFIC AETHALOMETER® MODEL AE33
MAGEE SCIENTIFIC AETHALOMETER® MODEL AE33
DUALSPOTTM – PATENTED TECHNOLOGY
SOURCE APPORTIONMENT – BIOMASS BURNING VS FOSSIL FUEL
MULTI WAVELENGTH OPERATION
RELIABLE AND HIGH QUALITY DATA
The Aethalometer collects and analyzes aerosol particles continuously. The aerosol-laden air stream is drawn through a spot on a filter tape at a measured flow rate. Simultaneously, the tape is illuminated by light: sensitive detectors measure the intensities of light transmitted through an un-exposed portion of the tape, acting as a reference; versus the collecting spot. As optically absorbing material accumulates on the spot, the intensity of light transmitted through it gradually decreases. The decrease in light intensity from one measurement to the next is interpreted as an increase in collected material. This increased amount is divided by the known air-flow volume to calculate the concentration.
In the new Magee Scientific Aethalometer® Model AE33, two sample spots are collected from the same input air stream with different accumulation rates and analyzed simultaneously. The two results are combined mathematically to eliminate the “Filter Loading Effect” nonlinearity and accurately measure the aerosol concentration.
Additionally, the analysis is made at 7 optical wavelengths spanning the spectrum from 370 nm to 950 nm. Increases in optical absorption at shorter wavelengths may be interpreted in terms of the presence of so-called “Brown” carbonaceous material, usually an indicator of emissions from biomass combustion.
The Magee Scientific Aethalometer® Model AE33 has been developed with input from the research and monitoring communities, and is designed for reliable operation under all conditions ranging from state‐of‐the‐art research to routine air-quality monitoring.
THE DUALSPOT™ MEASUREMENT METHOD
The Magee Scientific Aethalometer® Model AE33 incorporates the patented DualSpot™ measurement method. This completely solves the loading-dependent nonlinearity, which affects the data from any filter-based optical analyzer. The method explicitly does not require any knowledge or assumption about the existence, origin, or magnitude of any optical nonlinearity. In fact, the calculation yields the “Loading Compensation Parameter” as an instrumental data output, which may offer insights into the origins and optical properties of the aerosol.
7-WAVELENGTH OPERATION: UV-IR, 1HZ DATA
The analysis is performed at 7 optical wavelengths spanning from the near-infrared (950 nm) to the near-ultraviolet (370 nm). The sequencing of illumination and analysis is performed on a 1-Hz timebase. This yields the complete spectrum of aerosol optical absorption with one data line every second.
REAL-TIME SOURCE APPORTIONMENT
An Ångström Exponent model is used in real-time to calculate the fraction of BC that may be attributed to biomass combustion.
CALIBRATION AND IN-FIELD VALIDATION
The optical performance of the Magee Scientific Aethalometer® Model AE33 may be validated by the ‘Neutral Density Optical Filter Kit,’ consisting of four precision optical elements whose absorbance is traceable to fundamental standards. Software routines measure the optical intensities at all wavelengths and compare the analysis instantly with the original reference values. Other built-in test programs offer routine checks of stability and leakage. These features provide Quality Assurance that is essential both for routine monitoring and research use.
USER AND COMMUNICATIONS INTERFACES
User and communications interfaces permit remote monitoring of operation; data retrieval; performance of internal tests; and reporting of state-of-health parameters. Networked services offer automated status reports, issuing daily ‘Green’ reports when the instrument is functioning correctly; ‘Yellow’ reports when the instrument detects that it will need routine attention soon; and ‘Red’ reports immediately upon detecting any fault condition.
RUGGED, RELIABLE, AUTOMATIC
The Magee Scientific Aethalometer® has been developed over almost 40 years to offer rugged, reliable, and automatic operation. The AE33 recovers automatically from power interruptions and no operator attention is required for weeks or months, other than replacing the roll of filter tape.
The project of developing Magee Scientific Aethalometer® model AE33 was awarded as a Success story on the Eurostars joint programme webpage. Please check this link for the details.