Attribution of atmospheric sulfur dioxide over the English Channel to dimethyl sulfide and changing ship emissions

Abstract

Abstract. Atmospheric sulfur dioxide (SO 2 ) was measured continuously from the Penlee Point Atmospheric Observatory (PPAO) near Plymouth, United Kingdom, between May 2014 and November 2015. This coastal site is exposed to marine air across a wide wind sector. The predominant southwesterly winds carry relatively clean background Atlantic air. In contrast, air from the southeast is heavily influenced by exhaust plumes from ships in the English Channel as well as near Plymouth Sound. A new International Maritime Organization (IMO) regulation came into force in January 2015 to reduce the maximum allowed sulfur content in ships' fuel 10-fold in sulfur emission control areas such as the English Channel. Our observations suggest a 3-fold reduction in shipemitted SO 2 from 2014 to 2015. Apparent fuel sulfur content calculated from coincidental SO 2 and carbon dioxide (CO 2 ) peaks from local ship plumes show a high level of compliance to the IMO regulation (> 95 %) in both years (∼ 70 % of ships in 2014 were already emitting at levels below the 2015 cap). Dimethyl sulfide (DMS) is an important source of atmospheric SO 2 even in this semi-polluted region. The relative contribution of DMS oxidation to the SO 2 burden over the English Channel increased from about one-third in 2014 to about one-half in 2015 due to the reduction in ship sulfur emissions. Our diel analysis suggests that SO 2 is removed from the marine atmospheric boundary layer in about half a day, with dry deposition to the ocean accounting for a quarter of the total loss.

Seasonal and geographical variability of nitryl chloride and its precursors in Northern Europe

“…The Penlee Point Atmospheric Observatory (PPAO, http://www.westernchannelobservatory.org.uk/penlee/) is located ∼11 m above mean sea level and ∼30 m from the shoreline. The site receives unpolluted air from the Atlantic Ocean during prevailing southwesterly conditions (∼50% of the time, Yang et al, ). Weybourne (52°57′N, 01°07′E) is on the eastern coast of the United Kingdom, ∼180 km northeast of London. The Weybourne Atmospheric Observatory (WAO, http://weybourne.uea.ac.uk/) is located ∼150 m from the shoreline and receives clean air masses from the North Sea, as well as continental outflow from the United Kingdom and/or Northern Europe (Penkett et al, ).…”

“…The 1-min detection limit for ClNO 2 was 4.2 ppt at 2σ (5.1 ppt at 3σ), with 18% accuracy and 14% precision. O 3 was measured by UV absorption in Leicester (Model T400, Teledyne Technologies Inc., City of Industry, CA, Hama et al, 2017), in Penlee Point (Model 205, 2B Technologies, Boulder, CO, Yang et al, 2016) and in Weybourne (Model 49i, Thermo Fisher Scientific Inc., Franklin, MA). NO 2 was measured at Leicester and in Penlee Point with a Teledyne Model T200 NO/NO 2 /NO x analyser, using chemiluminescence detection with a molybdenum converter (Hama et al, 2017).…”

Air–sea fluxes of CO<sub>2</sub> and CH<sub>4</sub> from the Penlee Point Atmospheric Observatory on the south-west coast of the UK

“…Northeasterly wind comes over the Plymouth Sound to PPAO and is limited to a fetch of about 5 km. Air from the southeast is affected by pollution from the European continent as well as shipping emissions (Yang et al, 2016). In the southwesterly direction, the wind fetch is up to thousands of km and the wind speed sometimes exceeds 20 m s −1 .…”

Monitoring compliance with fuel sulfur content regulations of sailing ships by unmanned aerial vehicle (UAV) measurements of ship emissions in open water

“…The pollutant gases emitted 25 by ships not only affect the global climate (Huebert, 1999;Corbet, 2016), but also local air quality and can harm people's health. (Yang et al, 2016;Wang et al, 2019). Shipping accounted for 15%, 13%, and 3% of the annual global anthropogenic emissions of NOx, SOx, and CO2 from 2007to 2012, respectively (Smith et al, 2014.…”