MAGEE Scientific Aethalometer AE33 User Manual page 22

Aethalometer
Model AE33
5 INTRODUCTION
The Aethalometer model AE33 collects aerosol particles continuously by drawing the aerosol-
laden air stream through a spot on the filter tape. It analyzes the aerosol by measuring the
transmission of light through one portion of the filter tape containing the sample, versus the
transmission through an unloaded portion of the filter tape acting as a reference area. This
analysis is done at seven optical wavelengths spanning the range from the near-infrared to the
near-ultraviolet. The Aethalometer calculates the instantaneous concentration of optically-
absorbing aerosols from the rate of change of the attenuation of light transmitted through the
particle-laden filter. In the new Model AE33 Aethalometer, two measurements are obtained
simultaneously from two sample spots with different rates of accumulation of the sample.
Both spots derive their samples from the same input air stream. The two results are
combined mathematically to eliminate nonlinearities and provide the compensated particle
light absorption and BC mass concentration.
The method explicitly does not require any knowledge or assumption about the existence,
origin or magnitude of any optical nonlinearity arising from the properties of the aerosol
particles collected on the filter.
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User's manual – Ver. 1.55 July 2017 22/146