COBRA Project Objectives
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:
Specific objectives within COBRA that contribute towards the central objectives are:
- (1) To perform initial laboratory testing and validation for new instruments/techniques to be used within COBRA.
- (2) To produce a large high quality data set on the composition, properties and fluxes of gases and aerosols within a “bromine hot spot” of the Arctic boundary layer.
- (3) To characterise the physical and chemical nature of sea-ice/snowpack surfaces, frost-flowers, and the biological nature of any under-ice diatoms.
- (4) To determine the relative and/or combined roles of sea-ice, frost flowers, sea-salt enriched snow pack and biological sources in the exchange of halogens, ozone and particles in the field.
- (5) To conduct laboratory studies with frost flower surrogates and to examine the effect of temperature, pH, and other surface constituents on the exchange of trace gases.
- (6) To investigate the impact of iodine chemistry and sea-ice/snowpack/atmosphere exchange on ozone and mercury depletion.
- (7) To quantify the role (if any) of iodine emissions on new particle formation in the Arctic.
- (8) To determine the extent of halogen activation in autumn, throughout Hudson Bay.
- (9) To test in detail current parameterisations of bromine emissions from frost flowers within the global 3D model p-TOMCAT against a range of measurements and to examine the combined effects of bromine and iodine on tropospheric ozone on both global and regional scales.