Analysis of a southern sub-polar short-term ozone variation event using a millimetre-wave radiometer
<p>Subpolar regions in the Southern Hemisphere are influenced by the Antarctic polar vortex during austral spring, which induces high and short-term ozone variability at different altitudes, mainly into the stratosphere. This variation may affect considerably the total ozone column changing th...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-07-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/37/613/2019/angeo-37-613-2019.pdf |
| Summary: | <p>Subpolar regions in the Southern Hemisphere are
influenced by the Antarctic polar vortex during austral spring, which
induces high and short-term ozone variability at different altitudes, mainly
into the stratosphere. This variation may affect considerably the total
ozone column changing the harmful UV radiation that reaches the surface.</p>
<p>With the aim of studying ozone with a high time resolution at different altitudes
in subpolar regions, a millimetre-wave radiometer (MWR) was installed at the
Observatorio Atmosférico de la Patagonia Austral (OAPA), Río
Gallegos, Argentina (51.6<span class="inline-formula"><sup>∘</sup></span> S, 69.3<span class="inline-formula"><sup>∘</sup></span> W), in 2011. This instrument provides ozone profiles with a time resolution of
<span class="inline-formula">∼1</span> h, which enables studies of short-term ozone mixing
ratio variability from 25 to <span class="inline-formula">∼70</span> km in altitude. This work
presents the MWR ozone observations between October 2014 and 2015, focusing
on an atypical event of the polar vortex and Antarctic ozone hole influence
over Río Gallegos detected from the MWR measurements at 27 and 37 km
during November of 2014. During the event, the MWR observations at both
altitudes show a decrease in ozone followed by a local peak of ozone amount
of the order of hours. This local recovery is observed thanks to the high
time resolution of the MWR mentioned. The advected potential vorticity (APV)
calculated from the MIMOSA high-resolution advection model (Modélisation
Isentrope du transport Méso-échelle de l'Ozone Stratosphérique
par Advection) was also analysed at two isentropic levels (levels of
constant potential temperature) of 675 and 950 K (<span class="inline-formula">∼27</span> and
<span class="inline-formula">∼37</span> km of altitude, respectively) to understand and explain
the dynamics at both altitudes and correlate the ozone rapid recovery with
the passage of a tongue with low PV values over Río Gallegos. In
addition, the MWR dataset was compared for the first time with measurements
obtained from the Microwave Limb Sounder (MLS) at individual altitude levels (27, 37 and 65 km) and with the differential absorption lidar (DIAL)
installed in the OAPA to analyse the correspondence between the MWR and
independent instruments. The MWR–MLS comparison presents a reasonable
correlation with mean bias errors of <span class="inline-formula">+</span>5 %, <span class="inline-formula">−</span>11 % and <span class="inline-formula">−</span>7 % at 27,
37 and 65 km, respectively. The MWR–DIAL<span id="page614"/> comparison at 27 km also presents
good agreement, with a mean bias error of <span class="inline-formula">−</span>1 %.</p> |
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| ISSN: | 0992-7689 1432-0576 |