MAGEE Scientific AE33 User Manual page 10

Aethalometer
Model AE33
at different rates of accumulation, i.e. at different values of ATN. By combining the data
according to the above equations, the AE33 yields the value of BC extrapolated back to 'zero
loading'; as well as a real-time output of the 'loading compensation parameter' k which
provides insights into the aerosol nature and composition. This process is performed in real
time for all wavelengths: examination of the 'k' values as a function of wavelength provides
further information about the aerosol composition. An example of this is shown for extreme
concentrations of black carbon (Figure 3).
Figure 3. The time-series of AE33 raw and compensated BC concentrations with 1 second timebase – note
Automatic Zero and Span
The Aethalometer Model AE33 offers the capability for automatically checking the 'zero-air'
response of the instrument under dynamical operating conditions. This test is implemented
by back-flushing the inlet connection with an excess flow of internally-filtered air and
circulating the filtered air in the instrument. The data reported during this period are analyzed
for the mean value and the point-to-point variation. The mean value should be close to zero
under ideal conditions; any positive value greater than zero represents the leakage of BC-
containing room air into the instrument's analytical zone.
represents the instrument's measurement noise level under actual operating conditions of
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User's manual – Ver. 1.53
80000
60000
40000
20000
0
2000
the extreme concentrations and loading effects.
IR, 1 second
raw BC1
raw BC2
compensated BC
3000
time (sec)
July 2015
4000
The point-to-point variation
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