This study examines 1211 cases of coincident ozone profiles derived from 1164 Umkehrs and 928 SAGE II profiles within 1000 km and 12 hours between October 1984 and April 1989 to study the stratospheric-aerosol effect on Umkehr ozone profiles. Because of the close correspondence of stratospheric aerosol optical depth at the SAGE II-measured 0.525 micron wavelength and the extrapolated 0.32 Umkeh...

[1] Measurements of BrO suggest that inorganic bromine (Bry) at and above the tropopause is 4 to 8 ppt greater than assumed in models used in past ozone trend assessment studies. This additional bromine is likely carried to the stratosphere by short-lived biogenic compounds and their decomposition products, including tropospheric BrO. Including this additional bromine in an ozone trend simulati...

Stratospheric ozone is expected to recover by the end of this century because of the regulation of ozonedepleting substances by the Montreal Protocol. Targeted modeling studies have suggested that the climate response to ozone recovery will greatly oppose the climate response to rising greenhouse gas (GHG) emissions. However, the extent of this cancellation remains unclear since only a few such...

near surface ozone in urban areas can be potentially hazardous for the city dwellers. as a secondary pollutant it can also be an indicator for other air pollutants as nitrogen oxides, nox and phenol acetate nitrate (pan). in this paper time and spatial variations of near surface ozone and the effective meteorological parameters influencing it concentrations, have been investigated for tehran fo...

Following the eruption of Mount Pinatubo, satellite and in situ measurements showed a large enhancement in stratospheric aerosol in both hemispheres, but significant midlatitude column O3 depletion was observed only in the north. We use a three-dimensional chemical transport model to determine the mechanisms behind this hemispheric asymmetry. The model, forced by European Centre for Medium-Rang...

Using historical observations and model simulations, we investigate ozone trends prior to the mid-1970s onset of halogen-induced ozone depletion. Though measurements are quite limited, an analysis based on multiple, independent data sets (direct and indirect) provides better constraints than any individual set of observations. We find that three data sets support an apparent long-term stratosph...