Monday, 10 January 2000: 10:45 AM
1997 was notable for the anomalously low ozone observed at Southern Hemisphere middle latitudes. This is investigated through the analysis of the ozone mixing ratio distribution using all available satellite-based data. The Ozone Assimilation System (OASYS) uses Statistical Interpolation to analyse data every 6 hours onto a global 2.5 degree horizontal grid with 19 pressure levels between 1000 and 0.3hPa. Back trajectory Reverse Domain Filling is used to advect the analysed ozone to obtain the next first-guess field.
The evolution of lower stratospheric ozone in 1997 is described and validated against ozonesonde data. Potential reasons for the low ozone are examined.
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