The objectives of this project are:
1. Reevaluation of existing ozone records (both ground based and ozonesondes) from selected stations and compilation of homogeneous long term series of ozone and stratospheric circulation parameters through 1994.
2. Study of the effects of solar and geomagnetic activity on the reevaluated ozone records after removing the contribution of known quasi-periodic or aperiodic signals (i.e. QBO, ENSO, stratospheric warmings and volcanic effects).
3. Study of the solar effects on ozone, both for full series and series divided into the east and west phases of the QBO, in various solar cycles and different seasons.
4. Study of changes in ozone and associated changes in tropospheric and stratospheric circulation.
5. The impact of solar activity on the ozone layer variations will be investigated using recently developed models, which take into account heterogeneous chemistry (both aerosol perturbations and PSCs).
Total ozone data at a few selected stations with the longest available period of observations (1957 through 1994) will be re-evaluated and checked for homogeneity while inconsistencies will be removed. Reevaluated records of the vertical ozone distribution will also be used along with stratospheric circulation parameters (heights, temperatures and winds). Potential vorticity on a daily basis for at least one solar cycle will be calculated, homogenized and used together with the other data sets.
The first attempt will be to remove from the above data sets signals originating inside the atmospheric engine. These signals include the annual and semiannual cycles, the Quasi Biennial Oscillation (QBO), the El Nino/Southern Oscillation (ENSO), as well as transient phenomena with significant impact in the lower stratosphere such as stratospheric warmings and large volcanic eruptions. Lidar sites in Thule, the South Pole, at various locations at mid-latitudes including Rome, and the SAGE II data will provide precision measurements of the Pinatubo aerosols. The volcanic signal(s) will be removed from the data sets in the same way as the QBO and ENSO signals are subtracted from the series after objectively defining at each latitude the phase of the perturbation pertaining to each phenomenon. At the same time, model calculations will be made to provide a new look at previously suggested solar-stratospheric ozone relationships. A recently developed model which take into account heterogeneous chemistry (both aerosol particles and PSCs) will be used to investigate the impact of solar activity variations on ozone depleting chemistry. This part of the project will take into account recently observed volcanic perturbations in the ozone layer following the Pinatubo eruption.
Funding SchemeCSC - Cost-sharing contracts
3730 AE De Bilt