Examining novel atmospheric chemistry in the marine environment with an iodide chemical ionisation mass spectrometer
The marine atmosphere and ocean play an important role in controlling the abundance of aerosols and trace gases in the atmosphere. The interaction at the ocean-atmosphere interface can have important climate implications due to their effects on ocean biogeochemistry, cloud formation, atmospheric che...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2023
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| Online Access: | https://research.manchester.ac.uk/en/studentTheses/0524994b-e8d4-4552-9ba1-bad93eef6e90 https://pure.manchester.ac.uk/ws/files/261214924/FULL_TEXT.PDF |
| Summary: | The marine atmosphere and ocean play an important role in controlling the abundance of aerosols and trace gases in the atmosphere. The interaction at the ocean-atmosphere interface can have important climate implications due to their effects on ocean biogeochemistry, cloud formation, atmospheric chemistry and the Earth’s radiation budget. However, there are large uncertainties surrounding the role of marine ecosystems in the cycling of trace gases and aerosols in the atmosphere and ultimately how these interactions affect the climate. In order to address these uncertainties, more observational data are needed to be able to improve our understanding of the chemical composition and processes occurring within the marine environment. This thesis presents observations from several aircraft campaigns over the Eastern North Atlantic Ocean and provide novel measurements of biogenic trace gases measured using an iodide ion chemical ionisation mass spectrometer (I-CIMS). The extensive data presented here includes measurements from the Boreal Spring, Summer, Autumn and Winter and as such allows for the characterisation of marine emissions within the studied region. The measurements have identified novel species important to the marine reduced nitrogen and sulfur cycle, including the first observations of gas-phase urea in the atmosphere. Calibration methods were developed in order to provide humidity-corrected and quantitative measurements. Urea was found to be frequently enhanced within the marine boundary layer (MBL) and mixed well into the free-troposphere. The observations indicate that the surface ocean is a significant source of gas-phase urea to the atmosphere during large periods of the year, although no urea was detected during the Spring flights. The transport of biomass-burning and dust plumes over the remote marine environment are an additional source. Global model simulations suggest that the atmospheric burden of urea is significant to the reduced nitrogen budget. However, there are many uncertainties ... |
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