Macro Algae Emissions of Reactive Iodine (MAORI)

• Applicant: Denis Pöhler, Ph.D.
• Subject Area: Oceanography
• Term: from 2013 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 239352232

In the recent years it became clear, that halogen chemistry - beyond its well known influence on the stratospheric ozone plays an important role in chemical and physical processes in the troposphere. This is particularly evident within the marine boundary layer, but chemical processes related to reactive halogen species (RHS) i.e. halogen atoms, molecular halogens and oxidised halogen species may affect the entire troposphere. For example halogens emitted by macro algae are directly correlated to aerosol formation at coastal sites and thus influence the climate. However, many underlying mechanisms are presently not understood. Also the spatial emission and extent of the areas where halogen chemistry is of importance needs to be much better quantified. Especially in the mid latitudes measurements of the southern hemisphere RHS measurements are very sparse. The project will concentrate on studies of the above phenomena in marine air. A measurement campaign along coastal areas of New Zealand will focus on the emission of RHS by macro algae and will provide the first data for the southern hemisphere. The new information should allow a better quantification of the global importance of coastal halogen release. Field measurements will be performed with newly developed measurement techniques. We will apply beside a high sensitive LP-DOAS and MAX-DOAS (like applied before) a new mobile Cavity-Enhanced DOAS system for in-situ observations of halogens. Due to its size and weight, the new instruments allows in combination with the LP-DOAS and MAX-DOAS to quantify the spatial distribution of RHS, by moving or setting up the CE-DOAS at different locations. Dominant sources can thus be investigated. Formation of aerosols by iodine will be studied by aerosols profiles derived from MAX-DOAS.

• DFG Programme: Research Grants