 |
| Titel |
Variability of mesospheric water vapor above Bern in relation to the 27-day solar rotation cycle |
| VerfasserIn |
Martin Lainer, Klemens Hocke, Niklaus Kämpfer |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250124397
|
| Publikation (Nr.) |
 EGU/EGU2016-3826.pdf |
|
|
|
|
|
| Zusammenfassung |
| We investigate the solar-terrestrial response of mesospheric water vapor from a
mid-latitudinal observation site at the 27-day solar rotation cycle time scale. Eight years of
water vapor profile measurements above Bern (46.88∘N/7.46∘E) by the microwave
radiometer MIAWARA are used to study prominent oscillation features. The spectral data
analyses shows enhanced oscillations in the 27-day period band above 0.1hPa during the
rising sunspot activity of solar cycle 24. Aura MLS observations of H2O support these results
by showing a similar behavior. The relationship between mesospheric H2O and the solar
Lyman-α flux (FLyα) is studied by comparing the similarity of their temporal oscillations.
The H2O oscillation is negatively correlated to FLyα oscillation with a correlation coefficient
of up to −0.3 to −0.4, and the phase lag is 6–10 days on 0.04hPa. The confidence level of
the correlation is ≥ 99%.
Additionally we compute wavelet power spectra, cross-wavelet transform and wavelet
coherence (WTC). The latter shows significant (two σ level) correlations occurring
intermittently in the 27 and 13-day band with variable phase lock behavior. Large FLyα
oscillations appeared after the solar superstorm in July 2012 and the H2O oscillations show a
well pronounced anti-correlation. The competition between advective transport and
photo-dissociation loss of mesospheric H2O may explain the sometimes variable phase
relationship of mesospheric H2O and FLyα oscillations. Generally, the WTC analysis
indicates that solar variability causes observable photochemical and dynamical processes in
the mid-latitude mesosphere. |
|
|
|
|
|
|