The Aethalometer® operates on the same principle as the Particle Soot Absorption Photometer (AOSPSAP), i.e., continuously measuring the transmission of sample air through a filter substrate and collecting the absorbing aerosol particles in a filter. However, it employs more wavelengths (7) and has a movable filter (tape) to allow continuous operation over long periods without requiring filter changes. Throughout the ARM Program, there are currently 2-filter (AOSAETH2SPOT) aethalometers in operation.
The aethalometer is fundamentally designed to measure the concentration of atmospheric black carbon, which is formed through incomplete combustion of fossil fuels (e.g., diesel, coal), biofuel and biomass. As black carbon absorbs solar energy, it can influence climate through the the direct and indirect radiative effects.
As of now, please monitor the a1-level aosaeth2spot datastreams. When submitting DQPRs for the 2-spot aethalometers, please use the AETH instrument class under the AOS Group.
The AOSAETH is a component instrument within the Aerosol Observing System (AOS). For a more complete overview the AOS system and its general backing measurement theory, please see the AOS DQ Wiki page.
In the metrics table below, primary AOSAETH2SPOT measurements are listed below. These include:
There are currently no known issues for this instrument. Document some here.
Black carbon concentrations can occasionally start rapidly oscillating at all wavelengths. This instrument data noise will cause high measurement uncertainty. If you see this, please mention it in your DQAs (an issue like this may also require a DQPR).
Computer outages or data logging failures can occasionally cause missing data. These should be documented in your DQAs and may require a DQPR if data is missing for >24 hours.