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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union

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© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
26 Feb 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Measurement Techniques (AMT).
Fast time response measurements of particle size distributions in the 3–60 nm size range with the Nucleation Mode Aerosol Size Spectrometer
Christina Williamson1,2, Agnieszka Kupc1,2, James Wilson3, David W. Gesler4, J. Michael Reeves5, Frank Erdesz1,2, Richard McLaughlin1, and Charles A. Brock2 1Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO
2Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO , 80305-3337, USA
3Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, 80208-177, USA
4St. Mary's Academy, Englewood, CO 80113, USA
5Earth Observing Laboratory, National Center for Atmospheric Research, Boulder, CO, 80301
Abstract. Earth's radiation budget is affected by new particle formation (NPF) and the growth of these nanometer-scale particles to larger sizes where they can directly scatter light or act as cloud condensation nuclei (CCN). Large uncertainties remain in the magnitude and spatiotemporal distribution of nucleation (less than 10 nm diameter) and Aitken (10–60 nm diameter) mode particles. Acquiring size-distribution measurements of these particles over large regions of the free troposphere is most easily accomplished with research aircraft.

We report on the design and performance of an airborne instrument, the nucleation mode aerosol size spectrometer (NMASS), which provides size-selected aerosol concentration measurements that can be differenced to identify aerosol properties and processes or inverted to obtain a full size-distribution between 3 and 60 nm. By maintaining constant downstream pressure the instrument operates reliably over a large range of ambient pressures and during rapid changes in altitude, making it ideal for aircraft measurements from the boundary layer to the stratosphere.

We describe the modifications, operating principles, extensive calibrations, and laboratory and in-flight performance of two NMASS instruments operated in parallel as a 10-channel battery of condensation particle counters (CPCs) in the NASA Atmospheric Tomography Mission (ATom) to investigate NPF and growth to cloud-active sizes in the remote free troposphere. An inversion technique to obtain a size distributions from the discrete channels of the NMASS is described and evaluated.

Concentrations measured by the two NMASS instruments flying in parallel are self-consistent and also consistent with measurements made with an Optical Particle Counter. Extensive laboratory calibrations with a range of particle sizes and compositions show repeatability of the response function of the instrument to within 5–8 % and no sensitivity in sizing performance to particle composition. Particle number, surface area, and volume concentrations from the data inversion are determined to better than 20 % for typical particle size distributions. The excellent performance of the NMASS systems provides a strong analytical foundation to explore NPF around the globe in the ATom dataset.

Citation: Williamson, C., Kupc, A., Wilson, J., Gesler, D. W., Reeves, J. M., Erdesz, F., McLaughlin, R., and Brock, C. A.: Fast time response measurements of particle size distributions in the 3–60 nm size range with the Nucleation Mode Aerosol Size Spectrometer, Atmos. Meas. Tech. Discuss.,, in review, 2018.
Christina Williamson et al.
Christina Williamson et al.
Christina Williamson et al.


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Short summary
We describe the operating principle, design and performance of the Nucleation Mode Aerosol Size Spectrometer (NMASS), an instrument composed of five condensation particle counters measuring size selected particle concentrations between 3 and 60 nm. An inversion to recover size distributions from the data is evaluated. Calibrations of a two-NMASS system for measuring size distributions on the NASA Atmospheric Tomography Mission, and examples of its in-flight performance are presented.
We describe the operating principle, design and performance of the Nucleation Mode Aerosol Size...