08 Mar 2021

08 Mar 2021

Review status: this preprint is currently under review for the journal AMT.

Efficacy of a portable, moderate-resolution, fast-scanning DMA for ambient aerosol size distribution measurements

Stavros Amanatidis1,2, Yuanlong Huang1, Buddhi Pushpawela1, Benjamin C. Schulze1, Christopher M. Kenseth1, Ryan X. Ward1, John H. Seinfeld1, Susanne V. Hering2, and Richard C. Flagan1 Stavros Amanatidis et al.
  • 1California Institute of Technology, Pasadena, CA, USA
  • 2Aerosol Dynamics Inc., Berkeley, CA, USA

Abstract. Ambient aerosol size distributions obtained with a compact, scanning mobility analyzer, the Spider DMA, are compared to those obtained with a conventional mobility analyzer, with specific attention to the effect of mobility resolution on the measured size distribution parameters. The Spider is a 12-cm diameter radial differential mobility analyzer that spans the 10–500 nm size range with 30s mobility scans. It achieves its compact size by operating at a nominal mobility resolution R = 3 (sheath flow = 0.9 L/min, aerosol flow = 0.3 L/min), in place of the higher sheath-to-aerosol flow commonly used. The question addressed here is whether the lower resolution is sufficient to capture the dynamics and key characteristics of ambient aerosol size distributions. The Spider, operated at R = 3 with 30s up and down scans, was collocated with a TSI 3081 long-column mobility analyzer, operated at R = 10 with a 360s sampling duty cycle. Ambient aerosol data were collected over 26 consecutive days of continuous operation, in Pasadena, CA. Over the 20–500 nm size range, the two instruments exhibit excellent correlation in the total particle number concentrations and geometric mean diameters, with regression slopes of 1.13 and 1.00, respectively. Our results suggest that particle sizing at a lower resolution than typically employed is sufficient in obtaining the key properties of ambient size distributions.

Stavros Amanatidis et al.

Status: open (until 03 May 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2021-59', Anonymous Referee #1, 13 Apr 2021 reply
  • RC2: 'Comment on amt-2021-59', Anonymous Referee #2, 13 Apr 2021 reply
  • RC3: 'Comment on amt-2021-59', Anonymous Referee #3, 22 Apr 2021 reply

Stavros Amanatidis et al.

Video supplement

Ambient particle size distributions measured with the Spider DMA and the TSI long-column DMA in Pasadena, CA, between May 16–June 11, 2020 Stavros Amanatidis, Yuanlong Huang, Buddhi Pushpawela, Benjamin C. Schulze, Christopher M. Kenseth, Ryan X. Ward, John H. Seinfeld, Susanne V. Hering, and Richard C. Flagan

Stavros Amanatidis et al.


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Short summary
We assess the performance of a highly-portable instrument, the Spider DMA, in measuring ambient aerosol particle size distributions, with specific attention to its moderate sizing resolution (R = 3), that enabled its compact size. Long term field testing showed excellent correlation with a reference instrument over the 10–500 nm range. Our results suggest that moderate resolution is sufficient to obtain the key properties of ambient size distributions, enabling the design of smaller instruments.