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Title: The effects of cosmic ray intensity on the nucleation of atmospheric aerosol
Author: Dunne, Eimear Maria
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2012
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Nucleation is an important source of atmospheric aerosol. Throughout the free troposphere, inorganic nucleation is responsible for new particle formation, while organics and amines play role in the boundary layer. At present, •global aerosol models use parametrisations of inorganic nucleation based on theoretical calculations, kinetic or thermodynamic models; or atmospheric observations. The CLOUD project was designed to measure nucleation rates as accurately as possible, under the full range of atmospheric temperatures and concentrations of H2S04 , NH3 , and ions. This thesis presents the first parametrisation of inorganic nucleation based on controlled laboratory measurements of neutral and ion-induced nucleation in binary H2S04-H 20 and ternary H2S04-NH3-H20 systems. The CLOUD parametrisation is compared with the SAWNUC and IMN parametrisations of binary ion-induced nucleation, and with laboratory measurements from the CLOUD experiment. Concentrations of particles simulated by the global aerosol microphysics model GLOMAP using the CLOUD parametrisation are compared with atmospheric observations from aircraft and surface stations, and •with other simulations which include only primary aerosol emissions or a binary neutral nucleation parametrisation. The simulations which use the CLOUD parametrisation agree well with aircraft observations in the free troposphere, but under-predict particle concentrations in the boundary layer. Correlations between the intensity of galactic cosmic rays and proxies for the Earth's climate have been observed on timescales I ranging from days to millennia. One mechanism suggested to explain these correlations is a change in the ion-induced nucleation rate, which in turn could modulate cloud and aerosol radiative properties. Using the CLOUD parametrisation in GLOMAP, a radiative cloud albedo effect of -16.1 mW m2 is generated by changes in ionisation between solar minimum and solar maximum, which is negligible compared with the 240 mW m-2 radiative effect from changes in total solar irradiance over the same period.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available