The MILAN campaign: Studying diel light effects on the air-sea interface

Christian Stolle, Mariana Ribas-Ribas, Thomas H. Badewien, Jonathan Barnes, Lucy J. Carpenter, Rosie Chance, Lars Riis Damgaard, Ana María Durán Quesada, Anja Engel, Sanja Frka, Luisa Galgani, Blaženka Gašparović, Michaela Gerriets, Nur Ili Hamizah Mustaffa, Hartmut Herrmann, Liisa Kallajoki, Ryan Pereira, Franziska Radach, Niels Peter Revsbech, Philippa RickardAdam Saint, Matthew Salter, Maren Striebel, Nadja Triesch, Guenther Uher, Robert C. Upstill-Goddard, Manuela Van Pinxteren, Birthe Zäncker, Paul Zieger, Oliver Wurl

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


The sea surface microlayer (SML) at the air–sea interface is <1 mm thick, but it is physically, chemically, and biologically distinct from the underlying water and the atmosphere above. Wind-driven turbulence and solar radiation are important drivers of SML physical and biogeochemical properties. Given that the SML is involved in all air–sea exchanges of mass and energy, its response to solar radiation, especially in relation to how it regulates the air–sea exchange of climate-relevant gases and aerosols, is surprisingly poorly characterized. MILAN (Sea Surface Microlayer at Night) was an international, multidisciplinary campaign designed to specifically address this issue. In spring 2017, we deployed diverse sampling platforms (research vessels, radio-controlled catamaran, free-drifting buoy) to study full diel cycles in the coastal North Sea SML and in underlying water, and installed a land-based aerosol sampler. We also carried out concurrent ex situ experiments using several microsensors, a laboratory gas exchange tank, a solar simulator, and a sea spray simulation chamber. In this paper we outline the diversity of approaches employed and some initial results obtained during MILAN. Our observations of diel SML variability show, for example, an influence of (i) changing solar radiation on the quantity and quality of organic material and (ii) diel changes in wind intensity primarily forcing air–sea CO2 exchange. Thus, MILAN underlines the value and the need of multidiciplinary campaigns for integrating SML complexity into the context of air–sea interaction.
Original languageEnglish
Pages (from-to)E146–E166
Number of pages21
JournalBulletin of the American Meteorological Society
Issue number2
Early online date17 Oct 2019
Publication statusPublished - Feb 2020

ASJC Scopus subject areas

  • Atmospheric Science


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