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Centre for Atmospheric Science

COBRA Project Objectives

COBRA measurement site
The main COBRA measurement site on the coast of Hudson Bay.

The COBRA project is designed to address key uncertainties in the understanding of the observed ozone and mercury depletion and halogen release events. Specifically these uncertainties are associated with the nature of the surfaces involved, the important chemical species and chemical and physical mechanisms, and the temporal and spatial variability of active halogen release. Using a combination of field measurements, laboratory studies and a modelling program, the COBRA project aims to:

  • Develop understanding of the role of iodine (in concert with bromine) in Arctic gas phase photochemistry and aerosol production and evolution.
  • Investigate the relative/combined roles of frost flowers, older sea-ice/snow pack, sea salt aerosol and biological sources in releasing halogens to the Arctic atmosphere.
  • Increase understanding of the temporal and spatial variability of halogen-related ozone and mercury depletion events in the Arctic.
  • Develop and evaluate parameterisations for emission of halogens to the Arctic atmosphere based upon observable ice and meteorological conditions, and use these to develop improved models of Arctic chemistry and emissions and their effect and feedbacks on regional/global atmospheric chemistry and climate.
  • Specific objectives within COBRA that contribute towards the central objectives are:

    With the exception of number 3 Manchester’s measurement and modelling activities contributed to all of the specific COBRA objectives, and objectives 4 and 7 were co-ordinated by Manchester PI’s. Manchester’s key contributions were to measure ozone and particle fluxes (ultrafine and total) and aerosol size distributions, to construct chamber systems to examine emissions from different types of ice surface and to carry out aerosol production and evolution modelling.