Intercomparison of UV spectrometer and polarimeter on SMM and stratospheric aerosol and gas experiment II ozone profiles and trends in the lower mesosphere

Ozone concentrations obtained with the technique of solar occultation from the Solar Maximum Mission (SMM)/Ultraviolet Spectrometer and Polarimeter (UVSP) and Earth Radiation Budget Satellite (ERBS)/Stratospheric Aerosol and Gas Experiment II (SAGE II) satellite-borne instruments are compared in the latitude regions of 5 degrees to 15 degrees north and south for the lower mesosphere (53-68 km) for 1985-1989, the period when both instruments were operational. The estimated trends are all positive signifying increasing ozone. At 55 lan in the northern region they are 0.60(+/- 0.47)%/year for SAGE II and 2.56(+/-0.61)%/year for SMM/UVSP during the 1985-1989 period. At 60 km the trends are 0.38(+/-1.06)%/year for SAGE II and 1.63(+/-0.56)%/year for SMM/UVSP. Corresponding numbers at 55 km in the southern region are 1.23(+/-0.82)%/year for SAGE II and 2.38(+/-0.62)%/year for SMM/UVSP. At 60 lan the trends are 1.34(+/-1.01)%/year for SAGE II and 2.14(+/-0.56)%/year for SMM/UVSP. At 65 lan, where only SMM/UVSP data are used, estimated trends are 0.92(+/-0.74)%/year in the northern region and 2.59(+/-0.92)%/year in the southern region. Theory predicts that the increase in solar radiation between 1985 and 1989 should enhance ozone by 1.5%. If temperature feedback is included in the model, then ozone is predicted to decrease. These figures are smaller than the observed 5 to 10% increase. A long-term temperature decrease will also contribute to an ozone increase.