Analysis of the latitudinal variability of tropospheric ozone in the Arctic using the large number of aircraft and ozonesonde observations in early summer 2008

During the 2008 International Polar Year, the POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements, and Models of Climate Chemistry, Aerosols, and Transport) campaign, conducted in summer over Greenland and Canada, produced a large number of measurements from three aircraft and seven ozonesonde stations. Here we present an observation-integrated analysis based on three different types of O3 measurements: airborne lidar, airborne UV absorption or chemiluminescence measurement, and intensified electrochemical concentration cell (ECC) ozonesonde profiles.

Discussion of the latitudinal and vertical variability of tropospheric ozone north of 55° N during this period is performed with the aid of a regional model (WFR-Chem). The model is able to reproduce the O3 latitudinal and vertical variability but with a negative O3 bias of 6–15 ppbv in the free troposphere above 4 km, especially over Canada. For Canada, large average CO concentrations in the free troposphere above 4 km ( >  130 ppbv) and the weak correlation (   40 %) and the higher values of the 75th PV percentile.