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| Titel |
Convection: the likely source of the medium-scale gravity waves observed in the OH airglow layer near Brasilia, Brazil, during the SpreadFEx campaign |
| VerfasserIn |
S. L. Vadas, M. J. Taylor, P.-D. Pautet, P. A. Stamus, D. C. Fritts, H.-L. Liu, F. T. São Sabbas, V. T. Rampinelli, P. Batista, H. Takahashi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 27, no. 1 ; Nr. 27, no. 1 (2009-01-14), S.231-259 |
| Datensatznummer |
250016367
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| Publikation (Nr.) |
 copernicus.org/angeo-27-231-2009.pdf |
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| Zusammenfassung |
| Six medium-scale gravity waves (GWs) with horizontal
wavelengths of λH=60–160 km were
detected on four nights by Taylor et al. (2009) in the OH
airglow layer near Brasilia, at 15° S, 47° W, during the
Spread F Experiment (SpreadFEx) in Brazil in 2005.
We reverse and forward ray trace these GWs to the
tropopause and into the thermosphere using a ray trace model which
includes thermospheric dissipation.
We identify the convective plumes, convective clusters, and
convective regions which may have generated these GWs.
We find that deep convection is the highly likely source of four of
these GWs. We pinpoint the specific deep convective plumes which
likely excited two of these GWs on the nights of
30 September and 1 October.
On these nights, the source location/time uncertainties
were small and deep convection was sporadic
near the modeled source locations.
We locate the regions containing deep convective plumes and clusters
which likely excited the other two GWs.
The last 2 GWs were probably also excited from deep convection;
however, they must have been ducted ~500–700 km if so.
Two of the GWs were likely downwards-propagating initially
(after which they reflected upwards from the Earth's surface),
while one of the GWs was likely upwards-propagating initially
from the convective plume/cluster.
We also estimate the amplitudes and vertical scales
of these waves at the tropopause, and compare their scales
with those from a simple, linear convection model.
Finally, we calculate each GW's dissipation altitude, location,
and amplitude.
We find that the dissipation altitude depends sensitively
on the winds at and above the OH layer.
We also find that several of these GWs
may have penetrated to high enough altitudes to
potentially seed equatorial spread F (ESF)
if located somewhat farther from the magnetic equator. |
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