Distributions of Ozone and Nitric Acid Measured by the Limb Infrared Monitor of the Stratosphere (LIMS)

Abstract

The Limb Infrared Monitor of the Stratosphere (LIMS) experiment on the Nimbus 7 spacecraft provided seven months of data on the distribution of ozone and nitric acid. The evaluations of the accuracy, precision and resolution of these data is described before a description of the major features of their distributions is presented. The zonal mean for ozone shows a stratospheric layer, with largest mixing ratios in the tropics and maximum ozone mixing ratios at a given latitude occurring at 10 mb or higher. Nitric acid is distributed in a stratospheric layer that peaks near 30 mb, with the largest mixing ratios occurring in polar regions. Longitudinal variations for a month may be expressed as the sum of stationary and transient zonal harmonics. The amplitudes of the first harmonics can be up to 10–20% of the zonal mean in the winter, but only a few percent in the autumn, and very low in the spring and summer. The second harmonic is generally smaller. These features also appear in the monthly average maps. Time height cross-sections for both display seasonal variations that probably result from dynamical and chemical processes, and rapid dynamically induced fluctuations.

These and related data are making major contributions toward improving the understanding of the mechanisms required to maintain the observed distributions and their annual changes.