Ozone variability and halogen oxidation within the Arctic and sub-Arctic springtime boundary layer
Atmospheric Chemistry and Physics Discussions
The influence of halogen oxidation on the variabilities of ozone (O 3 ) and volatile organic compounds (VOCs) within the Arctic and sub-Arctic atmospheric boundary layer was investigated using field measurements from multiple campaigns conducted in March and April 2008 as part of the POLARCAT project. For the ship-based measurements, a high degree of correlation (r = 0.98 for 544 data points collected north of 68 • N) was observed between the acetylene to benzene ratio, used as a marker for
... as a marker for chlorine and bromine oxidation, and O 3 signifying the vast influence of halogen oxidation throughout the ice-free regions of the North Atlantic. Concurrent airborne and ground-based measurements in the Alaskan Arctic substantiated this correlation and were used to demonstrate that halogen oxidation influenced O 3 variability throughout the Arctic boundary layer during these springtime studies. Measurements aboard the R/V Knorr in the North Atlantic and Arctic Oceans provided a unique view of the transport of O 3 -poor air masses from the Arctic Basin to latitudes as far south as 52 • N. FLEXPART, a Lagrangian transport model, was used to quantitatively determine the exposure of air masses encountered by the ship to first-year ice (FYI), multi-year ice (MYI), and total ICE (FYI+MYI). O 3 anti-correlated with the modeled total ICE tracer (r = −0.86) indicating that up to 73% of the O 3 variability measured in the Arctic marine boundary layer could be related to sea ice exposure.