Theme 4: Interconnections between marine ecosystems, aerosols, and clouds

At any given moment, over half of the sky is covered by clouds and they are responsible for about 2/3 of the Earth’s albedo. Clouds are also a key component of the water cycle. Any change in cloud properties affects the Earth’s energy budget, as well as amounts of fresh water over the continents. Cloud formation depends on both meteorological parameters and availability of cloud condensation nuclei, thus, aerosols. The oceans, as an important source of primary and secondary aerosols, have a huge impact on clouds, especially in regions away from anthropogenic sources. Moreover, the strength and impact of the ocean sources of aerosols will vary with climate change. Theme 4 focuses on the interconnections between aerosols, derived from marine ecosystems, and clouds, with the overall goal to reduce the related climate uncertainties.

Theme 4 team


Team leaders

Maria Kanakidou (Greece,
Jurgita Ovadnevaite (Ireland,

Team members

Katye Altieri (South Africa,
Peter Croot (Ireland,
Santiago Gassó (United States,
Ilan Koren (Israel,
Mohd Talib Latif (Malaysia,
Caroline Leck (Sweden,
Maurice Levasseur (Canada,
Karine Sellegri (France,
Rainer Volkamer (United States,

Processes and impacts/stressors associated with long-lived greenhouse gases.

Ocean sources of atmospheric primary and secondary aerosol and subsequent atmospheric processing. Also shown are aerosols direct and indirect radiative impacts.

Research questions

Key questions to be addressed within this theme are:

  • How are aerosol load and properties linked to the marine ecosystem?
  • How and if anthropogenic emissions affect the natural abundance and properties of marine aerosol.
  • How do primary marine emissions and secondary aerosol formation processes influence aerosol activation of cloud droplets and ice crystals?
  • What are aerosol effects on marine clouds?
  • What are the feedbacks between clouds, the marine ecosystem, and climate?



Biological and environmental drivers
Conduct coordinated oceanic (physical, chemical and biological) and atmospheric (aerosols, CCNs, INPs, their physicochemical properties) measurements in order to constrain and model the biological and environmental drivers of biogenic aerosols.
Surface microlayer
Assess the chemical and biological properties of the ocean surface microlayer; determine how they compare with the properties of the ocean upper mixed layer, and how they relate to aerosol properties, thermodynamic profiles and cloud-relevant properties.
Time Series Stations
Develop and maintain a dedicated network of SOLAS Time Series Stations. The network will facilitate an assessment of short-term (through phytoplankton bloom phases) and long-term (through seasons and years) variations in primary and secondary ocean aerosol production/emission and their impacts on atmospheric chemistry and cloud properties. Provide access to the collected data via links on the SOLAS website.
Ocean-derived aerosol effects
Acquire high-quality and high-resolution measurements of the physical, chemical, and biological properties of the surface ocean mixed layer and the atmospheric marine boundary layer to decouple ocean-biogeochemical aerosol effects on marine clouds from physical effects, such as meteorology. This involves the development of techniques for identifying the most important players among marine secondary aerosol precursors (beyond dimethyl sulphide, isoprene, and iodine) and the determination of their sources, volatility, and aerosol yields (amines and semi-volatile hydrocarbons could be target candidates). It also involves techniques that allow for counting and characterising nascent ultra-small aerosols to better assess the frequency and mechanisms of particle nucleation in the marine boundary layer.
Remote sensing
Connect with the remote sensing community to develop new platforms, drones, and sensors, and work to inform the SOLAS community on remote sensing potentials. In addition, new space remote sensing platforms have become available in the recent years and may provide significant advances. Specifically, the new network of geostationary satellites (GOES 16/17, Himawari, GOCI, and others) make observations of clouds and aerosols over the ocean basins of interest every 10 minutes (day and night). For example, it will be possible to separate the effects of the meteorology with those due to aerosol-microphysics thanks to the time evolution information, also, a better understanding of the microphysical evolution of cloud properties will be gained with the better temporal information. In addition, better satellite detection of atmospheric composition (especially trace gases) has become available through the deployment of the TropOMI and GEMS satellites.
Cloud microphysics
Develop high-resolution numerical models to integrate cloud microphysics into small-scale process dynamics. Measurements of cloud microphysics above oceans needs to be addressed by developing small microphysical cloud probes that can be integrated on platforms such as drones or balloons.





Planned activities

See SOLAS Activities 2020-2021 table here

Research programs on marine ecosystems, aerosols, and clouds

Current national and international programs investigating marine ecosystems, aerosols, and clouds include the “Atmospheric Composition and Radiative forcing changes due to UN International Ship Emissions regulations” (ACRUISE), the program on “The Great Barrier Reef as a significant source of climatically relevant aerosol particles”, “Sea2Cloud: Are marine microorganisms influencing clouds?”, “Shipping Emissions in the Arctic and North Atlantic Atmosphere” (SEANA), and the North Atlantic Aerosols and Marine Ecosystems Study (NAAMES). Information on planned observational programs and workshops can be found via the respective program websites:


A workshop on Interconnections between aerosols, clouds, and marine ecosystems in contrasting environments, held in Rome, November 2018 brought together representatives of 10+ large European and International projects aiming to improving our understanding of the connection between ocean and aerosols and ultimately clouds. To maintain the momentum from that workshop, share their findings and improve communications as the different programs evolve, we will explore different options to strengthen the links between these programs (online exchanges, special session during conferences (AGU, EGU), workshops, etc.).
Interact with IGAC representatives at the 16th IGAC Science Conference, Manchester, UK, September 12-16, 2021, to investigate the opportunities in developing more collabo-rations between SOLAS and IGAC.
Engage with the aerosol community during the 21st ICNAA Conference, Brisbane, Australia, 2021.
Planning to submit a working group proposal on clouds to IUGG Grants Program 2020-2023 as joint IGAC-SOLAS initiative.