Remote Marine Atmosphere

Approximately 72% of our planet's surface is covered by oceans, yet the open ocean marine atmosphere is one of the most poorly probed atmospheric environments on our planet. We study OVOCs and halogens over remote oceans to quantify marine emissions of these gases and understand their source processes, with a focus on ocean surface processes and ocean-atmosphere interactions. Much remains to be known about the role these natural oceanic emissions play in atmospheric compositions and climate. Several field campaigns by ship and aircraft (VOCALS , TAO, HEFT-10, TORERO, WACS) and laboratory studies (Manchester) are dedicated to this field. Research topics include the study of organic carbon at marine interfaces and modeling of gas-phase chemistry.

Organic carbon at marine interfaces

 
  • Glyoxal has been detected over the open ocean by MAX-DOAS and CE-DOAS instruments on ships.
  • Glyoxal is a good tracer for the oxidative capacity in the marine boundary layer (MBL), as it is a sink for OH and tropospheric O3, which modify the reactive chemistry and lifetime of climate active gases, including CH4.
  • Flux measurements are made over the open ocean using the CE-DOAS to retrieve diurnal profiles of glyoxal over the ocean and to determine if the ocean is a glyoxal source or sink.

First detection of glyoxal over the remote ocean in the marine boundary layer during VOCALS-Rex/TAO 2008/2009.

Glyoxal flux measurements as a function of solar zenith angle (proxy for time) during TORERO.

Diurnal cycles of CHOCHO over the Eastern Pacific Ocean measured during TORERO.

Chemical modeling of trace gases

 
  • Explicit gas-phase models help us better understand MAX-DOAS and AMAX-DOAS measurements of trace gases including halogen oxides.
  • Measurements focus on the free troposphere where many species are observed but their existence is not yet explained.

Iodine budget for the free troposphere during TORERO. The model is constrained by IO measurements from the AMAX-DOAS. Trace levels of reactive iodine species play an important role in ozone depletion and oxidation capacity. In the lower part of the free troposphere, HOI is the most common species. Close to the tropopause, IO and I radicals are the most abundant species.