Large-Scale Ozone and Aerosol Variations Observed Over the Arctic During the ARCTAS Field Experiment

Ozone and aerosol distributions were measured with a differential absorption lidar (DIAL) on the NASA DC-8 aircraft during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field experiment. Remote ozone and aerosol profiles were simultaneously measured below and above the DC-8 to provide information from near the surface (~150 m AGL) to above the tropopause (~12-15 km) along the flight track. Multiple-wavelength aerosol backscatter measurements were made to estimate the relative size of the aerosols, and simultaneous aerosol depolarization measurements were made to detect the presence of nonspherical aerosols, such as mineral dust, and smoke plumes. In situ measurements of ozone made onboard the DC-8 were used to constrain the interpolation of the nadir and zenith ozone lidar measurements, which then provided an estimate of the entire tropospheric ozone profile along the flight track. DIAL ozone and aerosol measurements were made on all ARCTAS flights over the Arctic region during the spring (Apr) and summer (Jun-Jul) 2008 phases. Average latitudinal (~40-90N) and longitudinal (36-170W) variations of ozone and aerosols have been derived from these remote and in situ ozone data. The contribution of stratosphere-troposphere exchange to the latitudinal variation of ozone over the ARCTAS region has been estimated from potential vorticity values provided by the Regional Air Quality Modeling System (RAQMS) model. This paper discusses these results, compares and contrasts them between the two phases and a previous Arctic field experiment in 2000. We also relate the measurements to relative contribution of the various air mass types (long-range transport of pollution, biomass burning plumes, and stratosphere-troposphere exchange) that produce the observed large-scale variations in ozone and aerosols over the Arctic.