uhsas: Ultra-High Sensitivity Aerosol Spectrometer

The ultra-high-sensitivity aerosol spectrometer (UHSAS) is an optical-scattering, laser-based, aerosol particle spectrometer system for sizing particles in the 60 to 1000 nanometer (nm) range [1–3].

The instrument counts particles in up to 100 user-specified sizing bins. The instrument’s laser illuminates particles, which scatter light. The system captures the peak light signals that are generated. These signals are used for particle sizing, since the amount of light scattered correlates strongly with particle size.

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



  • Fixed
  • AMF1
  • AMF2
  • AMF3

Active Instrument Locations

Facility Name Instrument Start Date
Graciosa Island, Azores, Portugal 2014-02-17


Watson T, A Aiken, Q Zhang, P Croteau, T Onasch, L Williams, and C Flynn. 2020. Second ARM Aerosol Chemical Speciation Monitor Users’ Meeting Report. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-TR-249.

Gallo F, J Uin, S Springston, J Wang, G Zheng, C Kuang, R Wood, E Azevedo, A McComiskey, F Mei, A Theisen, J Kyrouac, and A Aiken. 2020. "Identifying a regional aerosol baseline in the eastern North Atlantic using collocated measurements and a mathematical algorithm to mask high-submicron-number-concentration aerosol events." Atmospheric Chemistry and Physics, 20(12), 10.5194/acp-20-7553-2020.

Zheng G, A Sedlacek, A Aiken, Y Feng, T Watson, S Raveh-Rubin, J Uin, E Lewis, and J Wang. 2020. "Long-range transported North American wildfire aerosols observed in marine boundary layer of eastern North Atlantic." Environment International, 139, 10.1016/j.envint.2020.105680.

Pennypacker S, M Diamond, and R Wood. 2020. "Ultra-clean and smoky marine boundary layers frequently occur in the same season over the southeast Atlantic." Atmospheric Chemistry and Physics, 20(4), 10.5194/acp-20-2341-2020.


Varble A, S Nesbitt, P Salio, E Avila, P Borque, P DeMott, G McFarquhar, S van den Heever, E Zipser, D Gochis, R Houze, M Jensen, P Kollias, S Kreidenweis, R Leung, K Rasmussen, D Romps, and C Williams. 2019. Cloud, Aerosol, and Complex Terrain Interactions (CACTI) Field Campaign Report. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-19-028.

Williamson C, A Kupc, D Axisa, K Bilsback, T Bui, P Campuzano-Jost, M Dollner, K Froyd, A Hodshire, J Jimenez, J Kodros, G Luo, D Murphy, B Nault, E Ray, B Weinzierl, J Wilson, F Yu, P Yu, J Pierce, and C Brock. 2019. "A large source of cloud condensation nuclei from new particle formation in the tropics." Nature, 574(7778), 10.1038/s41586-019-1638-9.

Jensen M, E Bruning, D Collins, A Fridlind, P Kollias, C Kuang, D Rosenfeld, A Ryzhkov, A Varble, SD Brooks, S Collis, E Defer, J Fan, J Flynn, S Giangrande, R Griffin, J Hu, R Jackson, M Kumjian, T Logan, T Matsui, G McFarquhar, C Nowotarski, J Quaas, M Oue, R Sheesley, J Snyder, P Stier, S Usenko, S van den Heever, M van Lier Walqui, Y Wang, Y Xu, and G Zhang. 2019. Tracking Aerosol Convection Interactions ExpeRiment (TRACER) Science Plan. Ed. by Robert Stafford, DOE/SC-ARM-19-017.

Wang J, R Wood, M Jensen, E Azevedo, C Bretherton, D Chand, C Chiu, X Dong, J Fast, A Gettelman, S Ghan, S Giangrande, M Gilles, A Jefferson, P Kollias, C Kuang, A Laskin, E Lewis, X Liu, Y Liu, E Luke, A McComiskey, F Mei, M Miller, A Sedlacek, and R Shaw. 2019. Aerosol and Cloud Experiments in Eastern North Atlantic (ACE-ENA) Field Campaign Report. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-19-012.

McFarquhar G, R Marchand, C Bretherton, S Alexander, A Protat, S Siems, R Wood, and P DeMott. 2019. Measurements of Aerosols, Radiation, and Clouds over the Southern Ocean (MARCUS) Field Campaign Report. Ed. by Robert Stafford, ARM user facility. DOE/SC-ARM-19-008.

Bretherton C, I Mccoy, J Mohrmann, R Wood, V Ghate, A Gettelman, C Bardeen, B Albrecht, and P Zuidema. 2019. "Cloud, Aerosol and Boundary Layer Structure across the Northeast Pacific Stratocumulus-Cumulus Transition as observed during CSET." Monthly Weather Review, 147(6), 10.1175/MWR-D-18-0281.1.

View All Related Publications