Description of the long-term ozone data series obtained from different instrumental techniques at a single location:: the Observatoire de Haute-Provence (43.9°N, 5.7°E)

A description of the long-term data series of stratospheric ozone at the Observatoire de Haute-Provence is presented. At this station, data sets with temporal length of a decade or more are provided in the framework of the Network for Detection of Stratospheric Change by ground-based experiments: Dobson spectrophotometer (in both column and Umkehr mode), lidar and ozonesondes. The data time series obtained from these various instruments operated simultaneously at a single site and complemented by SAGE II spaceborne measurements are first described with respect to instrumental uncertainties, sampling rate and time evolution. These data series are then compared to each other in terms of sampling rate and average vertical profiles. The difference between the mean ozone profiles of the data sets can partly be explained by the different sampling rate of the instruments. Using the overlap and the complementarity of the various data sets, a preliminary estimate of the long-term evolution of ozone over the last decade over Southern France is conducted. Trend values for both total column and vertical profiles are derived using the multi-regression statistical model AMOUNTS O-3. In the 25-40 km altitude range, a similar ozone decrease frost -4%/decade to -10%/decade is observed from lidar, Umkehr and SAGE II data series in good agreement with previous estimates. In the lower stratosphere (15-25 km), large negative trends in the ozone vertical profile are observed. In addition, the negative trend of -5.4%/decade in total ozone inferred from the Dobson measurements over the period 1983-1995 is in good agreement with the integrated trend profile.