The PIs will participate in a Surface Ocean Lower Atmosphere Study (SOLAS) investigation of halogen chemistry in the Cape Verde Islands during May-June 2007. The overall goal is to characterize reactive halogen cycling in the tropical North Atlantic marine boundary layer (MBL) and its impact on oxidation processes. The aims of this component are: 1) Measure and/or calculate the diel variability of important inorganic halogen species in the MBL; 2) Quantify source strengths and turnover rates of volatile and particulate halogens; 3) Evaluate potential influences of mineral aerosol on halogen cycling; and 4) Assess the effects of halogens on ozone, hydrocarbons, and sulfur. Hydrochloric acid (HCl), inorganic chlorine gases other than HCl, nitric acid (HNO3), ammonia (NH3), and volatile inorganic bromine and iodine will be measured as part of this project. Aerosol pH will be inferred and dry-deposition fluxes of gases and aerosols will be calculated. The results will be integrated with a comprehensive suite of halogen species, hydrocarbons, other trace gases, aerosol physical properties, and actinic flux data. Observations will be applied to test hypotheses of halogen chemistry and will be included in multiphase photochemical models. This research will address uncertainties in tropospheric halogen radical chemistry and its influences on ozone and aerosols. Broader impacts also include education of undergraduate and graduate students and strengthening international collaborations.
