Ozone variability in the troposphere and the stratosphere from the first 6 years of IASI observations (2008–2013)
In this paper, we assess how daily ozone (O<sub>3</sub>) measurements from the Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp-A platform can contribute to the analyses of the processes driving O<sub>3</sub> variability in the troposphere and the stratosph...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-05-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/5721/2016/acp-16-5721-2016.pdf |
| Summary: | In this paper, we assess how daily ozone (O<sub>3</sub>) measurements from the
Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp-A platform
can contribute to the analyses of the processes driving O<sub>3</sub> variability
in the troposphere and the stratosphere and, in the future, to the monitoring
of long-term trends. The temporal evolution of O<sub>3</sub> during the first
6 years of IASI (2008–2013) operation is investigated with multivariate
regressions separately in four different layers (ground–300, 300–150,
150–25, 25–3 hPa), by adjusting to the daily time series averaged in
20° zonal bands, seasonal and linear trend terms along with important
geophysical drivers of O<sub>3</sub> variation (e.g. solar flux, quasi-biennial
oscillation (QBO)). The regression
model is shown to perform generally very well with a strong dominance of the
annual harmonic terms and significant contributions from O<sub>3</sub> drivers, in
particular in the equatorial region where the QBO and the solar flux
contribution dominate. More particularly, despite the short period of the
IASI data set available up to now, two noticeable statistically significant
apparent trends are inferred from the daily IASI measurements: a positive
trend in the upper stratosphere (e.g. 1.74 ± 0.77 DU year<sup>−1</sup>
between 30 and 50° S), which is consistent with other studies
suggesting a turnaround for stratospheric O<sub>3</sub> recovery, and a negative
trend in the troposphere at the mid-latitudes and high northern latitudes
(e.g. −0.26 ± 0.11 DU year<sup>−1</sup> between 30 and 50° N),
especially during summer and probably linked to the impact of decreasing
ozone precursor emissions. The impact of the high temporal sampling of IASI
on the uncertainty in the determination of O<sub>3</sub> trend has been further
explored by performing multivariate regressions on IASI monthly averages and
on ground-based Fourier transform infrared (FTIR) measurements. |
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| ISSN: | 1680-7316 1680-7324 |