An analysis of more than 22,000 ozone profiles from Stratospheric Aerosol and Gas Experiment I (SAGE I) (1979–1981) and SAGE II (1984–1987) between 50°N and 50°S is used in conjunction with 9 years (1979–1987) of daily global depictions of total ozone from the Total Ozone Mapping Spectrometer (TOMS) instrument aboard Nimbus 7 to investigate the spatial distribution and seasonal cycle of the integrated amount of ozone in the troposphere. In the tropics, highest concentrations are found in the eastern Atlantic Ocean downwind (west) of Africa and maximize during the time when biomass burning is most prevalent, between July and October. A different seasonal cycle in the tropics is also observed over Indonesia where a relative maximum is present in the March–April time frame, likewise consistent with when biomass burning is most prevalent. At mid‐latitudes, highest concentrations are found downwind of Asia and maximize in the summer. Relatively higher amounts of tropospheric ozone are similarly observed downwind of North America and Europe. At mid‐latitudes, the ratio between the amount of tropospheric ozone in the northern hemisphere and the amount in the southern hemisphere is 1.4, in good agreement with in situ measurements. A detailed comparison of this satellite technique with available ozonesonde measurements suggests that the accuracy of this method for deriving the climatology of tropospheric ozone is probably better than 10% in the tropics and 15% at mid‐latitudes. We also show that TOMS total ozone measurements in the tropics can often be used independently to provide important qualitative insight into the behavior of tropospheric ozone at these low latitudes.

Climatologies of total columnar ozone and integrated stratospheric ozone amounts at low latitudes (15°N to 15°S), derived from satellite observations, are presented. A significant longitudinal variability in total ozone is present, with highest values generally located between 60°W and 60°E. The integrated stratospheric component of total ozone, on the other hand, does not exhibit a longitudinal preference for high values. Therefore we hypothesize that the climatological longitudinal distribution of total ozone reflects the variability of the abundance of tropospheric ozone at low latitudes. Furthermore, we speculate that in situ photochemical production of ozone resulting from biomass burning may be responsible for the observed enhancement of total ozone at these longitudes.

No abstract

No abstract

Water vapor observations obtained from the Stratospheric Aerosol and Gas Experiment II (SAGE II) solar occultation instrument for the troposphere and stratosphere are presented and compared with correlative in situ measurement techniques and other satellite data. The SAGE II instrument produces water vapor values from cloud top to approximately 1 mbar, except in regions of high aerosol content such as occurs in the low to middle stratosphere after volcanic eruptions. Details of the analysis procedure, instrumental errors, and data characteristics are discussed. Various features of the data set for the first $ years after launch (1985-1989) are identified. These include an increase in middle and upper tropospheric water vapor during northern hemisphere summer and autumn, thus at times of warmest sea surface temperature; minimum water vapor values of 2.5-3 ppmv in the tropical lower stratosphere, with lower values during northern hemisphere winter and spring; slowly increasing water vapor values with altitude in the stratosphere, reaching 5-6 ppmv or greater near the stratopause; extratropical values with minimum profile amounts occurring above the conventionally defined tropopause; and higher extratropical than tropical water vapor values throughout the stratosphere except in locations of possible polar stratospheric clouds. SAGE II data will be useful for studying individual water vapor profiles, tropospheric response to climate perturbations, troposphericstratospheric exchange (due to its inherent high vertical resolution), and stratospheric transports. It should also aid in the preparation, for the first time on a global scale, of climatologies of the stratosphere and the upper level cloud-free troposphere, for use in radiative, dynamical, and chemical studies.1.