Stratospheric Ozone Climatology

General

Using more than 1600 nighttime profiles obtained by the differential absorption lidars located at Table Mountain Facility (TMF) and Mauna Loa Observatory (MLO), Hawaii a 10-year and 6-year respectively stratospheric ozone climatology was performed. These two systems have been providing high-resolution vertical profiles of ozone number density between 15-50 km, several nights a week since 1988 (TMF) and 1993 (MLO). The presented climatology is typical of early night ozone values at both sites, and typical of a low solar activity period for MLO.

Figure 1 Figure 2
Figure 1 : Typical ozone profiles measured by the TMF (left) and MLO (right) lidars

The observed seasonal and vertical structure of the ozone concentration at TMF is consistent with that typical of mid- to subtropical latitudes (Figure 1). A clear annual cycle in opposite phase below and above the ozone concentration peak is observed (Figure 2). The observed winter maximum below the ozone peak is associated with a maximum day-to-day variability (Figure 4), typical of a dynamically driven lower stratosphere. The maximum concentration observed in summer above the ozone peak emphasizes the more dominant role of photochemistry (Figure 3a). Unlike TMF, the ozone concentration observed at MLO tends to be higher during the summer months and lower during the winter months throughout the entire stratospheric ozone layer (Figure 3b). Only a weak signature of the extra-tropical latitudes is observed near 19-20 km, with a secondary maximum in late winter. The only large variability observed at MLO is in the lowermost stratosphere which is believed to be associated with the natural variability of the tropical tropopause, and the influence of the Northern Hemisphere mid-latitudes and associated meridional transport.

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Figure 2: Annual variaitons of ozone measured at various altitudes by the TMF (left) and MLO (right) lidars.

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Figure 3: Composite ozone percentage deviaiton from caomposite annual mean as measured by lidar at TMF (left) and MLO (right)

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Figure 4: 33-day ozone standard deviation measured by the TMF (left) and MLO (right) lidars

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Figure 5: Ozone column amount (in DU) integrated between 20 km and the top of the profiles as measured by the TMF (left) and MLO (right) lidars

References

Leblanc, T., and I. S. McDermid, Stratospheric ozone climatology from lidar measurements at Table Mountain (34.4 ºN, 117.7ºW) and Mauna Loa (19.5ºN, 155.6ºW), J. Geophys. Res., 105, 14,613-14,623, 2000.

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