Year of grant:

Research Area:
Náttúra og náttúrutilfeingi

Project type:

Project title:
Kanning av eginleikunum hjá nano-partiklum úr havinum við Føroyar og hvussu gróðurin á landgrunninum ávirkar partiklarnar.

Grant number:

Project manager:
Sigurd Christiansen

Verkætlan á Aarhus Universitet

Other participants:
Marianne Glasius, Tina Santl-Temkiv, Bernadette Rosati, Knud Simonsen, Eilif Gaard, Karin Margretha H. Larsen og Matthew E. Salter

Project period:

Total budget:
kr. 1.544.151

Grant from the FRC in DKK:
kr. 536.040

Project description:
Sea spray aerosols that form when waves break are a part of everyday life in the Faroe Islands. They leave a layer of sea salt on all surfaces exposed to the wind, but sea spray aerosols are also important on a much larger scale through their role in Earth's climate system. Sea spray aerosols are one of the most important natural aerosols on Earth. These aerosol particles are formed by the action of wind on the ocean, which forms waves that subsequently break, entraining bubbles into the water. When these bubbles reach the ocean surface, they burst resulting in the release of many tiny droplets. These sea spray droplets affect global climate via their ability to scatter sunlight and/or act as a surface, where water can condense on to form clouds (a so-called cloud condensation nuclei, CCN). The particle production and properties are dependent on the chemical composition of the seawater, but the related chemical and physical processes are poorly understood. Our understanding of sea spray aerosol remains limited and establishing a connection between marine microbiological processes, sea spray aerosol composition, and cloud condensation nuclei is still an elusive challenge. The goal of this project is to understand and describe how chemical and physical properties of sea spray aerosols are linked to the spring/summer phytoplankton bloom around the Faroe Islands and to place the results in the context of global climate. The specific research questions we would like to address are the following: - Does the size distribution of sea spray particles generated from ocean water change as a result of the phytoplankton blooms during spring/summer in the water around the Faroe Islands? - Is there a change in chemical composition and CCN activity of sea spray aerosol generated from ocean water as a result of the phytoplankton bloom? - Is there a diurnal variation in sea spray aerosol properties? We propose intensive field campaigns in the Faroe Islands during spring / summer 2019 interconnected with laboratory experiments. We will locate our sampling station in Skopun, since there is a unique continues supply of ocean water and the additional benefits of the Faroe Marine Research Institute routine measurements. State of the art instrumentation will be available for sampling, e.g. the seawater, the sea surface microlayer and sea spray aerosol particles, to characterize chemical composition, aerosol properties and cloud condensation activity.

Breaking waves on the ocean surface emit sea spray aerosols to the atmosphere. These sea spray aerosols are a major source of uncertainty in climate models. The physical processes governing sea spray production play an important part in determining sea spray aerosol size, emission, and chemical composition. Sea spray affect climate directly by interaction with radiation from the sun or indirectly by acting as cloud condensation nuclei (CCN).

We conducted a three-week field campaign on the Faroe Islands during summer 2019 using a state-of-the-art sea spray simulation chamber. The campaign was conducted to investigate the impact of a phytoplankton bloom on both the particle production flux and the chemical composition of the particles.

Some key questions the campaign set out to answer were as follows:
1. Does the size-resolved number flux of SSA generated from ocean water change during phytoplankton blooms?
2. Is there a diurnal cycle in SSA production?
3. Can the presence of phytoplankton blooms impact the chemical composition of SSA and consequently their CCN activity significantly?

Main results suggests that the particle size distribution, the total number flux of aerosols produced in the chamber, and the critical supersaturation of dried sea spray aerosols at 80 nm were constant throughout the campaign. This is despite indications that the chemical composition of organic matter both the seawater and the SSA were impacted by the presence of the phytoplankton bloom.

Project status:

Project output:
Scientific articles, books, thesis etc.

Scientific articles:
Christiansen, S., Ickes, L., Bulatovic, I., Leck, C., Murray, B. J., Bertram, A. K., … Bilde, M. (2020). Influence of Arctic Microlayers and Algal Cultures on Sea Spray Hygroscopicity and the Possible Implications for Mixed-Phase Clouds. Journal of Geophysical Research: Atmospheres, 125(19), 1–16.

Rosati, B., Christiansen, S., Wollesen De Jonge, R., Roldin, P., Jensen, M. M., Wang, K., … Bilde, M. (2021). New Particle Formation and Growth from Dimethyl Sulfide Oxidation by Hydroxyl Radicals. ACS Earth and Space Chemistry, 5(4), 801–811.

Rosati, B., Christiansen, S., Dinesen, A., Roldin, P., Massling, A., Nilsson, E. D., & Bilde, M. (2021). The impact of atmospheric oxidation on hygroscopicity and cloud droplet activation of inorganic sea spray aerosol. Scientific Reports, 11(1), 10008.

PhD thesis:
Christiansen, S. (2020). Sea Spray Aerosols: Formation and Cloud Forming Potential. Aarhus Universitet. Defended 23rd October 2020

Other results, such as unpublished articles, patents, computer systems, original models and new procedures:

Manuscripts accepted for publication:
Wollesen de Jonge, R., Elm, J., Rosati, B., Christiansen, S., Hyttinen, N., Lüdemann, D., Bilde, M., and Roldin, P.: Secondary aerosol formation from dimethyl sulfide – improved mechanistic understanding based on smog chamber experiments and modelling, Atmos. Chem. Phys. Discuss. [preprint], , Accepted, 2021.

Manuscripts in preparation:
We are continuing the preparation of two manuscripts for scientific peer review in an open-access journal.

Christiansen, S., Radoman, N., Johanson, J., Salter, I., Jacobsen, S., Pedersen, H.B., Šantl-Temkiv, T., Salter, M.E., Bilde, M. (2021), Sea spray aerosols around the Faroe Islands: Particle size distributions and CCN activity during the initial phytoplankton growth phase. Manuscript to be submitted to RSC Environmental Science: Atmosphere

Radoman, N., Christiansen, S., Johanson, J., Bilde, M., Salter, M.E. (2021). Sea spray aerosols around the Faroe Islands: Chemical composition Manuscript to be submitted to RSC Environmental Science: Atmosphere

Publications outside the scientific community, i.e. lectures, periodicals, articles in newspapers, television and radio:

- PhD Slam, the Danish Society of Engineers, 06/11/2019 (oral, public presentation)

- PhD thesis. I was in the radio news on KVF and had a 10-15 min interview for the radio program “Nón”.

Storage and access rights til collected data:
The data collected during the campaign will be made available online at (open access).

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