CORDIS - EU research results

Ozone dry deposition to the sea surface microlayer

Project description

Modelling ozone deposition on one of the largest interfaces in the world

As ozone (O3) moves down from the stratosphere to the Earth's surface, this blocker of cancer-causing ultraviolet rays becomes the third most important greenhouse gas and an air pollutant harmful to human health, plant ecosystems, food security and the economy. O3 moves from the air to the Earth's surfaces in a process called dry deposition. Oceans cover 70 % of the Earth's surface and oceanic dry deposition is the largest yet most uncertain depositional sink, mainly due to challenges in measurement. O3-SML is combining modelling and ground-breaking experimental observations to more precisely quantify global ocean deposition flux, reducing the uncertainty in total global O3 dry deposition and informing climate models for improved prediction of future changes.


Tropospheric ozone is a significant climate gas and has a major influence on air quality, public health, and food security. Ozone is lost to the Earth’s surface directly by “dry deposition”, which is an important loss process for this gas. Since the ocean represents 70% of the surface, uncertainties in the dry deposition to the “sea surface microlayer” (SML) of the ocean translate into large differences in the predicted global ocean dry deposition flux. There has been very limited experimental quantification of ozone deposition over the oceans, because making such measurements is technically very challenging, and estimates of oceanic ozone deposition velocities vary widely. The mechanistic details of the process are incomplete and parameterisations in models are untested against observations. This loss of ozone is acknowledged to be controlled predominantly by chemical reactions in the SML involving iodide and organic material, which not only determine how quickly ozone can be irreversibly taken up at the ocean surface, but may also constitute a source of trace gases to the marine atmosphere. Whilst there is a growing body of work on ozone interactions with oceanic iodide, the nature and reactivity of the organic material in the SML which interacts with ozone is completely unknown. This project will probe both the fundamental mechanisms on and in the SML involved in the loss of ozone and production of atmospherically important trace gases and, in a highly novel and agenda-setting approach, apply this mechanistic information to field observations of oceanic ozone fluxes and the corresponding biogeochemical properties of the SML. This highly interdisciplinary study involves aspects of physical chemistry, atmospheric chemistry, ocean chemistry and physics, and engineering. It transcends conventional boundaries by integrating across atmospheric and ocean science, reflecting the PIs world-leading expertise in field and laboratory science in these fields.

Host institution

Net EU contribution
€ 2 364 087,00
YO10 5DD York North Yorkshire
United Kingdom

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Yorkshire and the Humber North Yorkshire York
Activity type
Higher or Secondary Education Establishments
Total cost
€ 2 364 087,00

Beneficiaries (3)