 |
| Titel |
Thermospheric Gravity Wave Activity near Summer Solstice 2014 Based on Analysis of Tromsø Dynasonde Data |
| VerfasserIn |
Nikolay Zabotin, Catalin Negrea, Oleg A. Godin, Michael Rietveld, Terence Bullett, Liudmila Zabotina |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104600
|
| Publikation (Nr.) |
 EGU/EGU2015-4029.pdf |
|
|
|
|
|
| Zusammenfassung |
| Propagation conditions for thermospheric gravity waves in the Polar Regions are
characterized by combination of several unique factors including interactions with the
Auroral activity and the polar vortex. Tropospheric sources of the acoustic gravity waves
(AGWs), such as wind disturbances caused by mountain relief, are likely to be
complemented by energy and momentum depositions associated with fluxes of
energetic particles from above. We apply recently developed Dynasonde techniques to
study peculiarities of the gravity wave characteristics over Northern Scandinavia. A
week-long (adjacent to the summer 2014 Solstice) data series for this study has been
obtained with the Dynasonde system at the EISCAT’s Tromsø Observatory operating
continuously with sounding session periodicity equal to 2 min. A component of
Dynasonde data analysis software, the inversion procedure NeXtYZ, has been used to
attribute plasma density, plasma contour tilts, and line-of-sight Doppler values to the
altitudes in real space with 1 km resolution. The temporal and spatial resolution allows
visualization of the phase fronts of the traveling ionospheric disturbances (TIDs) and
measuring the full set of parameters (both vertical and horizontal) of TID activity
in the upper atmosphere between the base of the E layer and the maximum of F
layer, where the ionospheric plasma can reflect the radar’s signal. We verify the
nature of the activity for selected spectral peaks by substituting the TID parameters
into the dispersion relation describing acoustic-gravity waves. Application of the
Lomb-Scargle periodogram technique to the tilt data provides useful insight into the
dynamics of spectral composition of the TIDs, which we compare to results of a
similar analysis obtained for mid-latitude (Wallops Island, VA) Dynasonde location.
Interference of wave packets and multi-path propagation are more frequent in polar
thermosphere compared to mid-latitude situation. Backtracking of selected waves
to their apparent source locations using a ray tracing technique with background
atmospheric parameters taken from the Whole Atmosphere Model (WAM) developed at
the NOAA/SWPC reveals mostly continental ground-level sources. Correlation
between measured spectral amplitudes of the wave activity at 200 km altitude and
attenuation of AGWs estimated from WAM parameters is tested as a quantitative
measure of AGWs originating in the troposphere and propagating in specific direction. |
|
|
|
|
|
|