Stratospheric ozone: Halogen Impacts in a Varying Atmosphere (SHIVA)

SHIVA aims to reduce uncertainties in present and future stratospheric halogen loading and ozone depletion resulting from climate feedbacks between emissions and transport of ozone depleting substances (ODS). Of particular relevance are studies of short and very short-lived halogenated substances (VSLS) with climate-sensitive natural emissions. To quantify the emissions of VSLS from the world’s oceans into the atmosphere, the composition and concentrations of water constituents, such as phytoplankton, dissolved and other particulate organic matter, are important factors.

To develop emission scenarios from global phytoplankton distributions, the Phytooptics group  provides climatologies of four different phytoplankton groups (diatoms, coccolitophores, dinoflagellates and cyanobacteria). The climatologies include monthly averages of a 9-year dataset (2003-2010) from hyperspectral satellite retrievals of the SCIAMACHY instrument aboard ENVISAT. Consequently, the VSLS emission scenarios are calculated by the IFM-GEOMAR to provide a basis to chemical transport models (CTM) for computing the transport and the potential ozone destruction in the stratosphere. From this a systematic global emission inventory of VSLS and ODS will be established to predict the rate and timing of the depletion of the stratospheric ozone-layer, which will allow better prediction of future climate scenarios.

Two ship cruises (TransBrom-Sonne, Oct. 2009 and Poseidon P399, Jun. 2010) have been carried out to investigate the interactions between oceanic constituents and the VSLS emissions into the atmosphere. The phytoplankton distributions from satellite data are compared to in-situ measurements of phytoplankton pigment (analysed by HPLC) and show reliable agreements. The main SHIVA field campaign will start in November 2011 at the Malaysian Sea and will combine measurements from land, ship, aircraft and space-based platforms.