pass > Photoacoustic Soot SpectrometerInstrument Type(s) > Baseline • Guest

The photoacoustic soot spectrometer (PASS) measures light absorption by aerosol particles. As the particles pass through a laser beam, the absorbed energy heats the particles and in turn the surrounding air, which sets off a pressure wave that can be detected by a microphone.

The PASS instruments can also simultaneously measure the scattered laser-light at three wavelengths and therefore provide a direct measure of the single-scattering albedo.

The PASS is part of the aerosol observing system (AOS).

Primary Measurements


  • Fixed
  • AMF1
  • AMF2
  • AMF3


Myers D, M Lawler, R Mauldin, S Sjostedt, M Dubey, J Abbatt, and J Smith. 2021. "Indirect Measurements of the Composition of Ultrafine Particles in the Arctic Late‚ÄźWinter." Journal of Geophysical Research: Atmospheres, 126(22), e2021JD035428, 10.1029/2021JD035428.


Li H, G McMeeking, and A May. 2020. "Development of a new correction algorithm applicable to any filter-based absorption photometer." Atmospheric Measurement Techniques, 13(5), 10.5194/amt-13-2865-2020.

Junghenn Noyes K, R Kahn, A Sedlacek, L Kleinman, J Limbacher, and Z Li. 2020. "Wildfire Smoke Particle Properties and Evolution, from Space-Based Multi-Angle Imaging." Remote Sensing, 12(5), 10.3390/rs12050769.


Forestieri S, T Helgestad, A Lambe, L Renbaum-Wolff, D Lack, P Massoli, E Cross, M Dubey, C Mazzoleni, J Olfert, A Sedlacek III, A Freedman, P Davidovits, T Onasch, and C Cappa. 2018. "Measurement and modeling of the multiwavelength optical properties of uncoated flame-generated soot." Atmospheric Chemistry and Physics, 18(16), 10.5194/acp-18-12141-2018.

Sheesley RJ, R Subramanian, C Flynn, M Dubey, N Hickmon, and S Yoon. 2018. Absorption at San Antonio with 3-Wavelength Photoacoustic Soot Spectrometer, Tricolor Absorption Photometer (ASAPT) Field Campaign Report. Ed. by Robert Stafford, ARM Climate Research Facility. DOE/SC-ARM-18-003.

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