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| Titel |
Probing the polar vortex for two-dimensional chemical and dynamical features with MIPAS-STR measurements in January and March 2010 during the RECONCILE Campaign |
| VerfasserIn |
Wolfgang Woiwode, Hermann Oelhaf, Thomas Gulde, Christof Piesch, Andreas Ebersoldt, Johannes Orphal |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250046129
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| Zusammenfassung |
| The MIPAS-STR (Michelson Interferometer for Passive Atmospheric Sounding –
Stratospheric Aircraft) instrument is an airborne FTIR limb-sounder and was operated
onboard the high-altitude stratospheric aircraft M55-Geophysica during the RECONCILE
Campaign in the arctic winter 2009/10. MIPAS-STR is measuring IR emission spectra of
atmospheric trace gases in the spectral range of 725-2100 cm-1 at an unapodized spectral
resolution of 0.036 cm-1. Depending on the strength of the spectral signatures of the
individual trace gases, ozone and many different ozone-relevant species can be analysed (e.g.
HNO3, ClONO2, ClO and different CFCs). From the spectra of MIPAS, vertical trace gas
profiles and cross-sections along the flight route are derived in the altitude-range of 5-20
km, at a vertical resolution of 1-2 km and a horizontal resolution across the flight
path of 20-40 km. The retrieval of the vertical trace gas profiles from the measured
spectra is performed using the Karlsruhe Optimised and Precise Radiative Transfer
Algorithm (KOPRA) and the inversion-tool KOPRAFIT. MIPAS-STR was operated
during the whole RECONCILE Campaign between January and March 2010, which
was based in Kiruna in Northern-Sweden. The scientific flights were carried out in
the area above and around Scandinavia and Spitzbergen, allowing for an extended
sampling of different chemical, microphysical and dynamical phases of the polar
vortex.
Vertical profiles and cross-sections of different trace-gases are shown for three
flights, covering three phases of the polar vortex during the winter and spring in
the beginning of 2010: (i) The cold, compact polar vortex at the end of January
directly after the end of a phase with extended PSC-coverage, (ii) the edge of the
late Canadian vortex remnant after the splitting event in February, sampled in the
beginning of March, and (iii) a vortex-filament at the very end of the polar winter in the
middle of March. Key aspects are the discussion of renitrification, chlorine activation
and filamentation in the different phases. The results are discussed in context with
ECMWF-analyses.
In particular, for the first selected flight of January 30th 2010, an air-mass with
strongly enriched HNO3 due to renitrification is found between 14 and 18 km altitude,
soon after the end of the extended PSC-phase. A correlated maximum is found for
ClONO2, which is likely to result from the in-situ-production from NO2 (resulting
from the HNO3-enrichment) and ClO. For the second selected flight of March 2nd
2010, the edge of the late Canadian part of the vortex after the splitting event can be
clearly identified, showing descended air with low concentrations of CFC-11 and
CFC-12, along with significantly increased concentrations of ClONO2. A separate
vortex-filament in the extra-vortex air is identified, characterised by a significant
enrichment of HNO3 and ClONO2. In the case of the last flight on March 10th 2010,
the vortex has largely dissolved and mixed with mid-latitude air, but still a broad
filament with a remnant of renitrified air is identified in the cross-section of HNO3. |
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