SIMULTANEOUS STRATOSPHERIC AEROSOL AND OZONE LIDAR MEASUREMENTS AFTER THE PINATUBO VOLCANIC-ERUPTION

Preliminary results of simultaneous ozone and aerosol lidar measurements taken in the period July-early October 1991 are presented. The main problem for retrieving the ozone profile is the correction of the on and off DIAL signals. The backscattering ratio obtained by the off signal is used for this purpose and ozone profiles are validated against ozonesonde data. A number of cases are presented including a few occasions of layers with large backscattering ratio. For these events the differences between ECC sonde and DIAL range between 5% to 20% and indicate that the method adopted for correction needs improvements especially for very thin layers. Sensitivity tests show that the retrieved ozone may change by roughly 10% depending on the choice of the aerosol optical parameters. Absolute difference between ECC and DIAL could not be completely explained in terms of the uncertainty in those parameters. The data obtained may still be used to prove the effects of heterogeneous chemistry on ozone destruction rate. Given the uncertainties introduced by the aerosol correction large amount of data need to be accumulated.