Validation of ACE-FTS v4.1 O3 with ozonesonde and lidar data

Abstract:

The newly released ACE-FTS v4.1 O3 profile dataset is compared with ozonesonde and lidar data from the NDACC (Network for the Detection of Atmospheric Composition Change) and WOUDC (World Ozone and Ultraviolet Radiation Data Centre) networks and with ozonesonde data from the SHADOZ (Southern Hemisphere ADditional OZonesondes) network. This study is divided into two parts, comparing the bias and the linear trend. First, the biases in the ACE-FTS O3 profiles versus the ground-based measurements are examined by analysing coincident data pairs. The relative differences from comparisons across the networks are derived. Then, the changes in O3 concentration over time are estimated from the ACE-FTS and ground-based instrument data sets. Because of the relatively sparse sampling of the ACE-FTS occultation measurements near many ground-based stations, large longitude ranges around the stations were used for the collocation criteria, even using zonal averages, to enable feasible trend estimations to be made. Interpretation and comparison of the ozone trends from ACE-FTS, ozonesonde and lidar measurements involves consideration of differences in the temporal and spatial sampling of the instruments, changes in ozone and instrument drifts. Results will be shown for groups of stations with similar latitudes to examine the consistency of the linear trend comparisons.