Indicators of Antarctic ozone depletion G. E. Bodeker1, H. Shiona1, and H. Eskes2 1National Institute of Water and Atmospheric Research, Lauder, New Zealand 2Koninklijk Nederlands Meteorologisch Instituut, De Bilt, The Netherlands
Abstract. An assimilated data base of total column ozone measurements from satellites
has been used to generate a set of indicators describing attributes of the
Antarctic ozone hole for the period 1979 to 2003, including (i) daily
measures of the area over Antarctica where ozone levels are below 150 DU,
below 220 DU, more than 30% below 1979 to 1981 norms, and more than 50%
below 1979 to 1981 norms, (ii) the date of disappearance of 150 DU ozone
values, 220 DU ozone values, values 30% below 1979 to 1981 norms, and
values 50% below 1979 to 1981 norms, for each year, (iii) daily minimum
total column ozone values over Antarctica, and (iv) daily values of the ozone
mass deficit based on a O3<220 DU threshold. The assimilated data base
combines satellite-based ozone measurements from 4 Total Ozone Mapping
Spectrometer (TOMS) instruments, 3 different retrievals from the Global Ozone
Monitoring Experiment (GOME), and data from 4 Solar Backscatter Ultra-Violet
(SBUV) instruments. Comparisons with the global ground-based Dobson
spectrophotometer network are used to remove offsets and drifts between the
different data sets to produce a global homogeneous data set that combines
the advantages of good spatial coverage of satellite data with good long-term
stability of ground-based measurements. One potential use of the derived
indices is detection of the expected recovery of the Antarctic ozone hole.
The suitability of the derived indicators to this task is discussed in the
context of their variability and their susceptibility to saturation effects
which makes them less responsive to decreasing stratospheric halogen loading.
It is also shown that if the corrections required to match recent Earth Probe
TOMS measurements to Dobson measurements are not applied, some of the
indictors are affected so as to obscure detection of the recovery of the
Antarctic ozone hole.
Citation: Bodeker, G. E., Shiona, H., and Eskes, H.: Indicators of Antarctic ozone depletion, Atmos. Chem. Phys., 5, 2603-2615, doi:10.5194/acp-5-2603-2005, 2005.