INVESTIGADORES
ALEXANDER Pedro Manfredo
congresos y reuniones científicas
Título:
GW activity and horizontal propagation above Southern Andes, Drake Passage and Antarctic Peninsula UTLS with GPS radio occultations and mesoscale simulations
Autor/es:
DE LA TORRE, A.; ALEXANDER, P.; LLAMEDO, P.; HIERRO, R.; A. ROLLA; SCHMIDT, T.; WICKERT, J.
Reunión:
Congreso; Occultations for Probing Atmosphere and Climate (OPAC) 4; 2010
Resumen:
The global distribution, generation and variability
of horizontal and vertical gravity waves (GWs) propagation, their energy
content and the vertical flux of horizontal momentum represent nowadays basic
ingredients in the understanding of the lower and middle atmosphere dynamics.
The UTLS region above the southern Andes Range, Drake Passage and Antarctic Peninsula constitute a natural laboratory where the
effect of orographic and non-orographic GW sources compete between them in the
total balance of wave energy. In this talk, we discuss recent results focused to
this region, as a preliminary stage to the accomplishment of the SAANGRIA
(Southern Andes-ANtarctic GRavity wave InitiAtive) Experiment. The objective of
the SAANGRIA project is to study the dynamics of GW in the Southern
Andes-Antarctic Peninsula region from the surface of the earth to the
mesosphere and lower thermosphere. We first describe a long-term seasonal and
geographical GW amplitudes, vertical wavelengths and activity from CHAMP and
COSMIC GPS RO T data. The observed features complement observations in the same
zone by other satellite passive remote sensing instruments able to detect
different height regions and other spectral intervals of the wave spectrum, and
by mesoscale WRF simulations. Topography is an important source and some strong
wave activity is also found over open ocean. Critical level filtering is shown
to have an attenuation effect, implying that a large fraction of the observed
activity can be considered to be an outcome of mountain waves. The wavefronts, nearly
aligned with the North-South direction, are easily detected by the nearly
meridional line of sight characterizing most of the GPS RO observations. We
adapt a previous method for the determination of horizontal propagation of
large amplitude GWs by Ern et al (2004). We consider triads of profiles,
instead of the usual subdivision in latitude-longitude cells, intending to
optimize the available information provided by the highly inhomogeneous
geographic distribution of GPS RO soundings. To remove the remaining p-phase uncertainty in the horizontal wave propagation
vectors we apply physical arguments. The geographic distribution of estimated
uncertainties in the determination of mean specific potential energy is
discussed.