Modification, calibration, and performance of the Ultra-High Sensitivity Aerosol Spectrometer for particle size distribution and volatility measurements during the Atmospheric Tomography Mission (ATom) airborne campaign

• Published in: Atmospheric measurement techniques 2018-01, Vol.11 (1), p.369-383
• Main Authors: Kupc, Agnieszka, Williamson, Christina, Wagner, Nicholas L, Richardson, Mathews, Brock, Charles A
• Format: Article
• Language: English
• Subjects: Aerosol spectrometers; Aerosols; Airborne sensing; Aircraft; Aircraft components; Ammonium; Ammonium compounds; Ammonium salts; Ammonium sulfate; Atmospheric aerosols; Atmospheric physics; Atmospheric research; Calibration; Chemical reactions; Control equipment; Earth; Earth atmosphere; Equipment and supplies; Equipment performance; Evaluation; Fiber optic equipment; Flow control; Inlets (waterways); Instruments; Instruments (Equipment); Laminar flow; Methods; Microphysics; Optical properties; Organic chemistry; Particle composition; Particle size distribution; Pressure; Pressure variations; Properties; Refractive index; Refractivity; Sensitivity; Sheaths; Size distribution; Spectrometers; Statistical methods; Statistics; Sulfates; Surface area; Tomography; Tropical climate; Troposphere; Uncertainty; Upper troposphere; Volatility
• ISSN: 1867-8548; 1867-1381; 1867-8548
• DOI: 10.5194/amt-11-369-2018

Atmospheric aerosol is a key component of the chemistry and climate of the Earth's atmosphere. Accurate measurement of the concentration of atmospheric particles as a function of their size is fundamental to investigations of particle microphysics, optical characteristics, and chemical processes. We describe the modification, calibration, and performance of two commercially available, Ultra-High Sensitivity Aerosol Spectrometers (UHSASs) as used on the NASA DC-8 aircraft during the Atmospheric Tomography Mission (ATom). To avoid sample flow issues related to pressure variations during aircraft altitude changes, we installed a laminar flow meter on each instrument to measure sample flow directly at the inlet as well as flow controllers to maintain constant volumetric sheath flows. In addition, we added a compact thermodenuder operating at 300 .sup.∘ C to the inlet line of one of the instruments. With these modifications, the instruments are capable of making accurate (ranging from 7 % for D.sub.p   0.13 µm), precise ( 1000 to 225 hPa, while simultaneously providing information on particle volatility.