Hemispheric Ozone Variability Indices
The diagnostics is designed to quantify the hemispheric total ozone variability related to zonal quasi-stationary planetary wave activity. Total ozone proves to be a valuable dynamical tracer for the lower stratosphere and can thus can be applied to illuminate the variability of wave structures. Using spectral statistical methods the amplitudes of the zonal quasi-stationary planetary waves in the lower stratosphere as traced by the ozone field can be extracted.
As diagnostic variables we introduce the hemispheric ozone variability indices number one and two. They are defined as the hemispheric mean amplitudes of the zonal waves number one and two, respectively. Daily satellilte observations of total ozone from TOMS and GOME since 1978 have been provided an excellent and consistent reference data set with proven accuracy for this diagnostic.
Total column ozone observations and according ozone fields of CCMs are analysed to trace the resulting hemispheric variability due to dynamical and chemical processes in the stratosphere:
1. Calculate monthly means of total column ozone (Dobson Units).
2. Apply spectral-statistical Harmonic Analysis (Bittner et al., 1994) to each latitude bin in order to derive the monthly mean amplitudes of the waves number one and two as traced by the total ozone field.
3. Derive hemispheric ozone variability indices one and two by calculating hemispheric mean of wave numbers one and two, respectively.
4. Calculate multi-year mean and standard deviation of indices one and two for each month and hemisphere.
Please note that the diagnostic is confined to the coverage of TOMS or GOME (polar night regions are excluded). For comparibilty reasons the Harmonic Analysis of the CCM data must be confined to those latitude bins covered by the satellite observations.
In order to guarantee a consistent and standardised procedure we offer to perform the diagnostics. Therefore, we kindly ask you to provide monthly means of total ozone. Please provide the data in ASCII fomat following the CCMVal data request (see 2D Monthly Mean Total Column Ozone Fields for the entire period - MEANTOZ).
Please note that the diagnostics is confined to the coverage of TOMS (polar night regions are excluded).
Erbertseder, T., Eyring, V., Bittner, M., Dameris, M. and V., Grewe: Hemispheric ozone variability indices derived from satellite observations and comparison to a coupled chemistry-climate model, Atmos. Chem. Phys., 6, 5105-5120, 2006
Wirth, V.: Quasi-stationary planetary waves in total ozone and their correlation with lower stratosphere temperature, J. Geophys. Res., 98, 8873-8882, 1993.
For questions, comments please contact Thilo Erbertseder
For total ozone data submission please contact Veronika Eyring.