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 and ice nuclei, thus, aerosols. The oceans, as an important source of primary and secondary aerosols, have a huge impact on the formation, lifetime and radiative properties of clouds, especially in regions away from anthropogenic sources. The complexity of aerosol formation (either from nucleation of precursor gas, primary production marine salt and organic particles, interaction with existing anthropogenic emissions, etc) is also a major hurdle as each pathway is known to result in different cloud formation potential. Moreover, the strength and impact of the ocean source 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,
Andrea Baccarini (Switzerland,
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 the marine ecosystems impact on atmospheric aerosol particle load and properties?
  • How do primary marine emissions and secondary aerosol formation processes influence aerosol activation of cloud droplets and ice crystals?
  • Under what conditions and how anthropogenic emissions affect the natural abundance and properties of marine aerosol
  • What are the ocean-biogeochemical aerosol effects on marine cloud radiative properties, lifetime and precipitation?
  • Identify and quantify possible feedbacks between the marine ecosystems, clouds, and climate


Priorities - Methodology & Tools

Biological and environmental drivers
Conduct coordinated oceanic (physical, chemical and biological) and atmospheric (aerosols, CCNs, INPs, their physicochemical properties) measurements in order to gain new knowledge with subsequent constraint-based modelling of the biological and environmental drivers of primary and secondary marine 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 the properties of atmospheric particles, thermodynamic profiles and cloud-relevant properties.
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.
Development of new techniques
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. Moreover, new techniques are required for both identifying how marine biogenic polymer gels (poly-saccharides, proteins, peptides, amino acids and lipids) interact to influence the aerosol ejection mechanism of bursting bubbles at the sea-air interface and aerosol cloud nucleating behaviour together with 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). Finally new techniques that allow for counting and characterising nascent ultra-small (< 3 nm diameters) to small (ca. 20 - 40 nm) aerosol particles are needed to better assess the frequency and mechanisms of particle nucleation and early growth in the marine boundary layer.
Time series stations - measuring platforms
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.
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. Upcoming polarimetric remote sensing also seems promising in that better aerosol type detection will be achieved but at the same time, polarimetric remote sensing maybe only effective at aerosol loadings well above the background levels commonly found in the marine environment.
Development of high-resolution numerical models that integrate cloud microphysics into small-scale process dynamics to advance the knowledge in aerosol-cloud interactions and climate effects.




Planned activities

Research programmes on marine ecosystems, aerosols, and clouds

Current national and international programs investigating marine ecosystems, aerosols, and clouds include the "Polar-Change: aerosol emissions from polar changing environments", oceanographic cruise near Antarctica, "MAP-IO Marion Dufresne Atmospheric Program Indian Ocean" - continuous atmospheric and oceanic measurements on board the R/V Marion Dufresne, "Atmospheric Composition and Radiative forcing changes due to UN International Ship Emissions regulations" (ACRUISE), the programme 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 programme 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.).

  • Engage with the marine aerosol and cloud community during:

Joint SOLAS-CNAA special session at the 21st ICNAA Conference, Brisbane, Australia, 2023. Deadline for abstract submission 3rd February 2023.

EGU SOLAS/GESAMP session AS2.6 "Air-sea Chemical Fluxes: Impacts on Biogeochemistry and Climate" April 23-28, 2023, Vienna. Deadline for abstract submission January 10th, 2023

  • SOLAS related SCOR working groups:

SCOR Working Group 163: Coupling of ocean-ice-atmosphere processes: from sea-Ice biogeochemistry to aerosols and Clouds (CIce2Clouds).

SCOR Working Group 166: Developing resources for the study of Methylated Sulfur compound cycling PROcesses in the ocean (DMS-PRO).