Evaluation of ozone measurements from a tethered balloon-sampling platform at South Pole Station in December 2003

Vertical boundary-layer ozone profiles were measured from a tethered balloon platform during the 2003 Antarctic Tropospheric Chemistry Investigation (ANTCI) at South Pole Station, Antarctica. Electrochemical concentration cell (ECC) ozonesondes were used in obtaining 128 ascent and descent profile measurements to about 500 m height during 13–30 December 2003. Various data checks and intercomparisons were done to confirm the accuracy of the ozonesondes. The ozonesondes compared well to a surface ozone ultra-violet (UV) absorption monitor located next to the tether balloon site. During the 18-day period, ozonesonde measurement checks at the surface averaged 0.2±1.0 ppbv higher than the continuous ozone measurements under ambient concentrations ranging from 18 to 51 ppbv. This agreement was also consistent when compared to the nearby NOAA UV-monitor sampling at 17 m above ground level during well-mixed conditions near the surface. In addition to the single ECC sonde profiles, five dual ECC ozonesondes were run on the tether platform. Four release balloon-borne ozonesondes were also launched during the project. Under very sharp ozone gradient events, the release ozonesonde (with a rise rate of ∼4–6 m s−1) passed through the gradient layer too quickly to capture the detail as measured by the controlled tethersonde at ∼0.3 m s−1 ascent/descent rate. Another method of ozone profiling was also done utilizing the UV monitor at the tether site and a 135-m-long Teflon sampling line with a sampling inlet mounted to and raised with the tethered balloon. The ECC ozonesonde averaged about 0.7±0.8 ppbv lower than the long-line sampling method from eight profiles.