Development of a Pressure-Controlled Inlet (PCI) coupled with a PM2.5 lens for the Aerosol Mass Spectrometer (AMS) measurements in the lower stratosphere on aircraft platforms
Abstract
Aerosols in the upper troposphere and lower stratosphere (UTLS) are crucial to understanding radiative forcing, ice cloud formation and ozone chemistry. Typically, fast chemical composition measurements are essential. Mass spectrometers such as the Aerodyne Aerosol Mass Spectrometer (AMS) can be used for these measurements. Such instruments typically use an aerodynamic lens as an inlet that collimates aerosols into a small detection volume without major size biases. However, such lenses depend on a constant pressure to work consistently, and airborne interfaces that provide that (pressure-controlled inlets -PCI-) have historically performed poorly at high altitudes. In this study, we are developing and testing a new PCI coupled with a PM2.5 aerodynamic lens towards the goal of sampling PM1 aerosols up to ~16 km altitude. We use state-of-the-art fluid dynamic model to inform the development and testing. We characterize the transmission efficiency (TE) as a function of aerodynamic diameter over the range of pressures relevant for airborne sampling. As a tool for this work, we are developing a field-deployable evaporation/condensation system optimized for fine monodisperse OA particle generation in the range 0-200 nm. This would allow reduced uncertainty in the in-field calibration of small size TE. In order to further investigate the characteristics of aerosol beam shape and its impact on TE, we use an aerosol Beam Width Probe (BWP) inside the instrument, and we are developing an automated computer-controlled mechanical lens alignment system.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA218.0016K
- Keywords:
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- 0317 Chemical kinetic and photochemical properties;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0340 Middle atmosphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0394 Instruments and techniques;
- ATMOSPHERIC COMPOSITION AND STRUCTURE