 |
| Titel |
Quasi 18-hour wave activity in ground-based observed mesospheric H2O over Bern, Switzerland |
| VerfasserIn |
Martin Lainer, Klemens Hocke, Rolf Rüfenacht, Franziska Schranz, Niklaus Kämpfer |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250139928
|
| Publikation (Nr.) |
 EGU/EGU2017-3249.pdf |
|
|
|
|
|
| Zusammenfassung |
| Observations of oscillations in the abundance of middle atmospheric trace gases can provide
insight into the dynamics of the middle atmosphere. Long term, high temporal resolution and
continuous measurements of dynamical tracers within the strato- and mesosphere are rare, but
would be important to better understand the impact of planetary and gravity waves on
the middle atmosphere. Here we report on water vapor measurements from the
NDACC (Network for the Detection of Atmospheric Composition Change) affiliated
ground-based microwave radiometer MIAWARA located close to Bern during two winter
periods of 6 months from October to March. Oscillations with periods between 6
and 30 hours are analyzed in the pressure range 0.01–10 hPa. Seven out of twelve
months have the highest wave amplitudes between 15 and 21 hour periods in the
mesosphere above 0.1 hPa. The quasi 18-hour wave is studied in more detail. We examine
the temporal behavior and use SD-WACCM simulations for comparison and to
derive characteristic wave features considering low-frequency gravity-waves being
involved in the observed water vapor oscillations. The 18-hour wave is also found in
SD-WACCM horizontal wind data and in measured zonal wind from the microwave
Doppler wind radiometer WIRA. For two cases in January 2016 we derive the
propagation direction, intrinsic period, horizontal and vertical wavelength of the model
resolved 18-hour wave. A south-westward to westward propagation with horizontal
wavelengths of 1884 and 1385 km and intrinsic periods close to 14 h are found. Vertical
wavelengths are typically below 6 km. We were not able to single out a distinct temporal
correlation between 18-hour band-pass filtered water vapor and wind data time series,
although H2O should mostly be dynamically controlled in the mesosphere and
sub-diurnal time range. More sophisticated numerical model studies are needed to
uncover the manifold effects of gravity waves on the abundance of chemical species. |
|
|
|
|
|
|