CIMA   09099
CENTRO DE INVESTIGACIONES DEL MAR Y LA ATMOSFERA
Unidad Ejecutora - UE
artículos
Título:
Gravity Waves above Andes Detected from GPS Radio Occultation Temperature Profiles: Jet mechanism?
Autor/es:
DE LA TORRE, A., ALEXANDER P., LLAMEDO P., MENÉNDEZ C., SCHMIDT T., WICKERT J.
Revista:
GEOPHYSICAL RESEARCH LETTERS
Editorial:
American Geophysical Union
Referencias:
Año: 2006 vol. 33 p. 1 - 5
ISSN:
0094-8276
Resumen:
A significant wave activity (WA) in the upper troposphere
and lower stratosphere, mainly during winter, was
detected at midlatitudes in the southern hemisphere (30
40S) above the Andes Range, from an analysis of Global
Positioning System Radio Occultation (GPS RO) temperature
profiles retrieved by CHAMP (CHAllenging Minisatellite
Payload) and SAC-C (Sate´lite de Aplicaciones
Cientý´ficas-C) Low Earth Orbit (LEO) satellites, between
May 2001 and February 2006. The possible main gravity
wave sources in this region are: i) orographic forcing, ii)
geostrophic adjustment and iii) deep convection. The available
vertical resolution of GPS RO soundings does not rule
out any of these alternatives. Based on satellite imaginary,
the WA enhancements cannot be attributed to deep convection
events. Inertia-gravity waves (IGWs) could be generated
after a geostrophic adjustment process, following a
perturbation of the zonal jet situated above the Andes
Mountains by mountain waves (MWs). The monthly WA
intensity follows the zonal wind velocity strength according
to its seasonal variability at jet altitudes. As the GPS-LEO
lines of sight are roughly meridionally aligned and the morphology
of the Andes at middle latitudes is predominantly
north-south, it was possible to detect MWs as well as IGWs
from GPS RO temperature profiles. This characteristic does
not apply for other mountain range alignments. From the
analysis of a numerical simulation at the time and location
of a single RO event with very strong WA, two main modes
of oscillation with horizontal wavelength around 40 and
200 km were identified. The first one is attributed to a MW
and the second one to an IGW. Citation: de la Torre, A., P.
Alexander, P. Llamedo, C. Mene´ndez, T. Schmidt, and J. Wickert
(2006), Gravity waves above the Andes detected from GPS radio
occultation temperature profiles: Jet mechanism?, Geophys. Res.
Lett., 33, L24810, doi:10.1029/2006GL027343.Citation: de la Torre, A., P.
Alexander, P. Llamedo, C. Mene´ndez, T. Schmidt, and J. Wickert
(2006), Gravity waves above the Andes detected from GPS radio
occultation temperature profiles: Jet mechanism?, Geophys. Res.
Lett., 33, L24810, doi:10.1029/2006GL027343.Geophys. Res.
Lett., 33, L24810, doi:10.1029/2006GL027343., 33, L24810, doi:10.1029/2006GL027343.