Next-generation ice-nucleating particle sampling on board aircraft: characterization of the High-volume flow aERosol particle filter sAmpler (HERA)

<p>Atmospheric ice-nucleating particle (INP) concentration data from the free troposphere are sparse but urgently needed to understand vertical transport processes of INPs and their influence on cloud formation and properties. Here, we introduce the new High-volume flow aERosol particle filter...

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Main Authors: S. Grawe, C. Jentzsch, J. Schaefer, H. Wex, S. Mertes, F. Stratmann
Format: Article
Language:English
Published: Copernicus Publications 2023-10-01
Series:Atmospheric Measurement Techniques
Online Access:https://amt.copernicus.org/articles/16/4551/2023/amt-16-4551-2023.pdf
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author S. Grawe
C. Jentzsch
J. Schaefer
H. Wex
S. Mertes
F. Stratmann
author_facet S. Grawe
C. Jentzsch
J. Schaefer
H. Wex
S. Mertes
F. Stratmann
author_sort S. Grawe
collection DOAJ
description <p>Atmospheric ice-nucleating particle (INP) concentration data from the free troposphere are sparse but urgently needed to understand vertical transport processes of INPs and their influence on cloud formation and properties. Here, we introduce the new High-volume flow aERosol particle filter sAmpler (HERA) which was specially developed for installation on research aircraft and subsequent offline INP analysis. HERA is a modular system consisting of a sampling unit and a powerful pump unit, and it has several features which were integrated specifically for INP sampling. Firstly, the pump unit enables sampling at flow rates exceeding 100 L min<span class="inline-formula"><sup>−1</sup></span>, which is well above typical flow rates of aircraft INP sampling systems described in the literature (<span class="inline-formula">∼</span> 10 L min<span class="inline-formula"><sup>−1</sup></span>). Consequently, required sampling times to capture rare, high-temperature INPs (<span class="inline-formula">≥</span> <span class="inline-formula">−</span>15 <span class="inline-formula"><sup>∘</sup></span>C) are reduced in comparison to other systems, and potential source regions of INPs can be confined more precisely. Secondly, the sampling unit is designed as a seven-way valve, enabling switching between six filter holders and a bypass with one filter being sampled at a time. In contrast to other aircraft INP sampling systems, the valve position is remote-controlled via software so that manual filter changes during flight are eliminated and the potential for sample contamination is decreased. This design is compatible with a high degree of automation, i.e., triggering filter changes depending on parameters like flight altitude, geographical location, temperature, or time. In addition to presenting the design and principle of operation of HERA, this paper describes laboratory characterization experiments with size-selected test substances, i.e., SNOMAX<sup>®</sup> and Arizona Test Dust. The particles were sampled on filters with HERA, varying either particle diameter (300 to 800 nm) or flow rate (10 to 100 L min<span class="inline-formula"><sup>−1</sup></span>) between experiments. The subsequent offline INP analysis showed good agreement with literature data and comparable sampling efficiencies for all investigated particle sizes and flow rates. Furthermore, the collection efficiency of atmospheric INPs in HERA was compared to a straightforward filter sampler and good agreement was found. Finally, results from the first campaign of HERA on the High Altitude and LOng range research aircraft (HALO) demonstrate the functionality of the new system in the context of aircraft application.</p>
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spelling doaj.art-efff764270bf49b8885ebaa8fe91fc662023-10-12T08:20:18ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482023-10-01164551457010.5194/amt-16-4551-2023Next-generation ice-nucleating particle sampling on board aircraft: characterization of the High-volume flow aERosol particle filter sAmpler (HERA)S. GraweC. JentzschJ. SchaeferH. WexS. MertesF. Stratmann<p>Atmospheric ice-nucleating particle (INP) concentration data from the free troposphere are sparse but urgently needed to understand vertical transport processes of INPs and their influence on cloud formation and properties. Here, we introduce the new High-volume flow aERosol particle filter sAmpler (HERA) which was specially developed for installation on research aircraft and subsequent offline INP analysis. HERA is a modular system consisting of a sampling unit and a powerful pump unit, and it has several features which were integrated specifically for INP sampling. Firstly, the pump unit enables sampling at flow rates exceeding 100 L min<span class="inline-formula"><sup>−1</sup></span>, which is well above typical flow rates of aircraft INP sampling systems described in the literature (<span class="inline-formula">∼</span> 10 L min<span class="inline-formula"><sup>−1</sup></span>). Consequently, required sampling times to capture rare, high-temperature INPs (<span class="inline-formula">≥</span> <span class="inline-formula">−</span>15 <span class="inline-formula"><sup>∘</sup></span>C) are reduced in comparison to other systems, and potential source regions of INPs can be confined more precisely. Secondly, the sampling unit is designed as a seven-way valve, enabling switching between six filter holders and a bypass with one filter being sampled at a time. In contrast to other aircraft INP sampling systems, the valve position is remote-controlled via software so that manual filter changes during flight are eliminated and the potential for sample contamination is decreased. This design is compatible with a high degree of automation, i.e., triggering filter changes depending on parameters like flight altitude, geographical location, temperature, or time. In addition to presenting the design and principle of operation of HERA, this paper describes laboratory characterization experiments with size-selected test substances, i.e., SNOMAX<sup>®</sup> and Arizona Test Dust. The particles were sampled on filters with HERA, varying either particle diameter (300 to 800 nm) or flow rate (10 to 100 L min<span class="inline-formula"><sup>−1</sup></span>) between experiments. The subsequent offline INP analysis showed good agreement with literature data and comparable sampling efficiencies for all investigated particle sizes and flow rates. Furthermore, the collection efficiency of atmospheric INPs in HERA was compared to a straightforward filter sampler and good agreement was found. Finally, results from the first campaign of HERA on the High Altitude and LOng range research aircraft (HALO) demonstrate the functionality of the new system in the context of aircraft application.</p>https://amt.copernicus.org/articles/16/4551/2023/amt-16-4551-2023.pdf
spellingShingle S. Grawe
C. Jentzsch
J. Schaefer
H. Wex
S. Mertes
F. Stratmann
Next-generation ice-nucleating particle sampling on board aircraft: characterization of the High-volume flow aERosol particle filter sAmpler (HERA)
Atmospheric Measurement Techniques
title Next-generation ice-nucleating particle sampling on board aircraft: characterization of the High-volume flow aERosol particle filter sAmpler (HERA)
title_full Next-generation ice-nucleating particle sampling on board aircraft: characterization of the High-volume flow aERosol particle filter sAmpler (HERA)
title_fullStr Next-generation ice-nucleating particle sampling on board aircraft: characterization of the High-volume flow aERosol particle filter sAmpler (HERA)
title_full_unstemmed Next-generation ice-nucleating particle sampling on board aircraft: characterization of the High-volume flow aERosol particle filter sAmpler (HERA)
title_short Next-generation ice-nucleating particle sampling on board aircraft: characterization of the High-volume flow aERosol particle filter sAmpler (HERA)
title_sort next generation ice nucleating particle sampling on board aircraft characterization of the high volume flow aerosol particle filter sampler hera
url https://amt.copernicus.org/articles/16/4551/2023/amt-16-4551-2023.pdf
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