Representativeness of single lidar stations for zonally averaged ozone profiles, their trends and attribution to proxies
Résumé
This paper is focusing on the representativeness
of single lidar stations for zonally averaged ozone profile
variations over the middle and upper stratosphere. From the
lower to the upper stratosphere, ozone profiles from single
or grouped lidar stations correlate well with zonal means
calculated from the Solar Backscatter Ultraviolet Radiome-
ter (SBUV) satellite overpasses. The best representativeness
with significant correlation coefficients is found within
15
of latitude circles north or south of any lidar station. This
paper also includes a multivariate linear regression (MLR)
analysis on the relative importance of proxy time series for
explaining variations in the vertical ozone profiles. Stud-
ied proxies represent variability due to influences outside
of the earth system (solar cycle) and within the earth sys-
tem, i.e. dynamic processes (the Quasi Biennial Oscilla-
tion, QBO; the Arctic Oscillation, AO; the Antarctic Os-
cillation, AAO; the El Niño Southern Oscillation, ENSO),
those due to volcanic aerosol (aerosol optical depth, AOD),
tropopause height changes (including global warming) and
those influences due to anthropogenic contributions to at-
mospheric chemistry (equivalent effective stratospheric chlo-
rine, EESC). Ozone trends are estimated, with and with-
out removal of proxies, from the total available 1980 to
2015 SBUV record. Except for the chemistry related proxy
(EESC) and its orthogonal function, the removal of the other
proxies does not alter the significance of the estimated long-
term trends. At heights above 15 hPa an “inflection point”
between 1997 and 1999 marks the end of significant nega-
tive ozone trends, followed by a recent period between 1998
and 2015 with positive ozone trends. At heights between 15
and 40 hPa the pre-1998 negative ozone trends tend to be-
come less significant as we move towards 2015, below which
the lower stratosphere ozone decline continues in agreement
with findings of recent literature
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