Abstract
Abstract. This paper contains a comprehensive investigation of the sunset–sunrise difference (SSD, i.e., the sunset-minus-sunrise value) of the ozone mixing ratio in the latitude range of 10° S–10° N. SSD values were determined from solar occultation measurements based on data obtained from the Stratospheric Aerosol and Gas Experiment (SAGE) II, the Halogen Occultation Experiment (HALOE), and the Atmospheric Chemistry Experiment–Fourier transform spectrometer (ACE–FTS). The SSD was negative at altitudes of 20–30 km (−0.1 ppmv at 25 km) and positive at 30–50 km (+0.2 ppmv at 40–45 km) for HALOE and ACE–FTS data. SAGE II data also showed a qualitatively similar result, although the SSD in the upper stratosphere was 2 times larger than those derived from the other data sets. On the basis of an analysis of data from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) and a nudged chemical transport model (the specified dynamics version of the Whole Atmosphere Community Climate Model: SD–WACCM), we conclude that the SSD can be explained by diurnal variations in the ozone concentration, particularly those caused by vertical transport by the atmospheric tidal winds. All data sets showed significant seasonal variations in the SSD; the SSD in the upper stratosphere is greatest from December through February, while that in the lower stratosphere reaches a maximum twice: during the periods March–April and September–October. Based on an analysis of SD–WACCM results, we found that these seasonal variations follow those associated with the tidal vertical winds.
Highlights
Stratospheric ozone (O3) plays a critical role in the climate system through radiative processes while simultaneously protecting the Earth’s surface from harmful ultraviolet radiation
We see that Halogen Occultation Experiment (HALOE) and Atmospheric Chemistry Experiment–Fourier transform spectrometer (ACE–FTS) agree well with each other for the entire stratosphere; SD–WACCM results at times of satellite coincidence are quantitatively consistent in the stratosphere
Considering that the SD–WACCM results at Stratospheric Aerosol and Gas Experiment (SAGE) II measurement locations are consistent with those at both HALOE and ACE–FTS measurement locations, we suggest that the anomalous SAGE II values were not due to the differences in the measurement locations/times compared to HALOE or ACE–FTS
Summary
Stratospheric ozone (O3) plays a critical role in the climate system through radiative processes while simultaneously protecting the Earth’s surface from harmful ultraviolet radiation. Useful data sets for long-term monitoring of vertical profiles of ozone levels can be obtained from solar occultation instruments, such as the Stratospheric Aerosol and Gas Experiment (SAGE) II (McCormick, 1987; McCormick et al, 1989), the Halogen Occultation Experiment (HALOE) (Russell et al, 1993), and the Atmospheric Chemistry Experiment–Fourier transform spectrometer (ACE–FTS) (Bernath et al, 2005), as they have measurements that are self-calibrating and have high sensitivity. Sakazaki et al.: Sunset–sunrise difference in solar occultation ozone measurements
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