 |
| Titel |
Numerical simulation of mesospheric gravity waves |
| VerfasserIn |
Andreas Dörnbrack, Markus Rapp, Ralph Latteck |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250077926
|
|
|
|
|
|
| Zusammenfassung |
| Recently, first three-dimensionally resolved observations of polar mesospheric winter echeos
(PMWEs) by a multi-beam experiment of the Middle Atmosphere Alomar Radar system
(MAARSY) were published by Rapp et al. (2011). The observed PMWE at about 75 km
altitude was tilted in the main flow direction (west to east). The origin of the PMWE was
explained by two disparate concepts of gravity wave dynamics. On the one hand, the tilted
PMWE was assumed to be aligned with the phase line of a linear gravity wave
(λz - 23 km, λx - 460 km) propagating at an intrinsic phase speed of - 73 m/s
against the westerly wind. On the other hand, turbulence generated by breaking
gravity waves was a necessary element to explain the existence of backscattering
fluctuations.
In addition to a thorough analysis of the synoptic meteorological conditions,
high-resolution numerical simulations are performed with the all-scale geophysical flow
solver EULAG (Prusa et al., 2008). The anelastic and pseudo-incompressible approximated
equations are solved in a 3D computational domain covers a 1500 km long slice of
Scandinavia and spans from the surface to 100 km altitude. Multiple numerical
experiments are performed to explore the origin of the observed PMWE. Various
hypotheses are tested. The presentation will discuss if the PMWEs were the result of
breaking mountain waves excited by the flow over Scandinavia or if dynamical
instabilities occuring in the highly sheared mesospheric flow led to the observed
turbulence.
Rapp, M., R. Latteck, G. Stober, et al., 2011: First three-dimensional observations of
polar mesosphere winter echoes: Resolving space-time ambiguity. J. Geophys. Res., 116,
A11307, doi:10.1029/2011JA016858.
Prusa, J.M., P.K. Smolarkiewicz, A.A. Wyszogrodzki, 2008: EULAG, a computational
model for multiscale flows, Comput. Fluids 37, 1193-1207. |
|
|
|
|
|
|