An Airborne Time of Flight Aerosol Mass Spectrometer

Lead Research Organisation: University of Manchester
Department Name: Earth Atmospheric and Env Sciences


The atmosphere is known to contain large amounts of particulate matter. Numbers can range from several tens of thousands of particles per cubic centimetre of polluted air to mere hundreds in more remote locations. As well as being known to affect human health, they have a significant control on the earth's climate, as they can scatter and absorb solar radiation. They are also thought to indirectly affect climate by dictating the properties of clouds and hence their microphysical and optical properties. However, many of the processes and properties that govern large parts of the lifecycle of aerosols in the atmosphere remain quantitatively uncertain, or in some cases unknown, and this must be addressed to improve predictions of aerosol effects. This is being achieved through laboratory and field measurement programmes and model development, the latter requiring field measurements to test their validity. Part of our lack of understanding and the lack of available model data is due to difficulties in accurately measuring the size and composition of particles in a variety of environments. This is particularly true of the organic fraction, which normally consists of a highly complex mixture of different chemical species. Current models tend to under-predict the amounts of organics in by a large factor, especially in the upper atmosphere, where measurements are scarce. Traditionally methods for measuring particle compositions are offline and so need significant time for sample collection. This is unsuitable for aircraft work, where measurements taken over the course of minutes or less are desired. The UK Facility for Airborne Atmospheric Measurements currently uses an Aerodyne Aerosol Mass Spectrometer (AMS) on many of its activities to measure particle compositions and sizes in real time. While this instrument has proved highly useful in studying aerosol compositions in polluted environments, it lacks the sensitivity to be able to study background particles, especially at higher altitudes within the troposphere or when studying aerosol composition in rapidly changing environments such as pollution plumes and cloud systems. We are proposing to develop this instrument further, using technology proven on the ground, to allow us to probe areas of uncertainty in the aerosol lifecycle such as organic aerosols within the free troposphere; the evolution of aerosols within the atmosphere after emission and aerosol-cloud interaction in greater detail than was possible previously. We will then show its capability and versatility in a series of demonstration experiments that focus on two areas of current scientific uncertainty: the composition of aerosols at many altitudes within the free troposphere, especially their organic content, and the evolution of aerosols within the atmosphere shortly after emission in pollution plumes. The instrument is also capable of probing the chemical nature of the particles that act as sites for cloud droplet formation. We will show its effectiveness at doing this using a size selecting inlet already installed on the FAAM to sample cloud droplets. These experiments will demonstrate the power of the new instrument and, as importantly, will highlight how the new instrument can probe aerosol processes in the atmosphere in the future.


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Aan De Brugh J (2012) Modelling the partitioning of ammonium nitrate in the convective boundary layer in Atmospheric Chemistry and Physics

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Allan J (2014) Airborne observations of IEPOX-derived isoprene SOA in the Amazon during SAMBBA in Atmospheric Chemistry and Physics

Description - new airborne capability for online aerosol chemical measurement

- assessment of European particle emissions databases

- quantification of African biomass burning aerosol abundances

- determination of south American pollution over the subtropical Pacific Ocean

- Assessment of biogenic secondary organic aerosol over Borneo

- Quantification of pollution aerosol over the Arctic region

- Quantifying emissions of biomass burning aerosol over Canada and Brazil
Exploitation Route The findings have been widely used to test models of air pollution. This is one of the most widely used data sets from the FAAM aircraft.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Energy,Environment,Transport

Description This grant supported the development of a new instrument, the aerosol mass spectrometer, on the NERC-Met Office Facility for Airborne Atmospheric Measurements (FAAM). The instrument development has not in itself led to significant impact but has massively increased the capability of the aircraft. It has flown on over 30% of the aircraft missions flown since 2004 and has delivered a wealth of data to a wide community of researchers and users including testing pollution and visibility model performance for the Met Office; assessing emissions over the UK for DEFRA, constraining numerical weather prediction models in Europe, Africa and Brazil, and contributing to global constraint of climate models through a number of major comparison exercises.
First Year Of Impact 2004
Sector Energy,Environment,Transport
Impact Types Societal,Economic,Policy & public services