Wave activity at ionospheric heights above the Andes Mountains detected from FORMOSAT‐3/COSMIC GPS radio occultation data

Torre, A. de la; Alexander, P.; Llamedo, P.; Hierro, R.; Nava, B.; Radicella, S. M.; Schmidt, T.; Wickert, Jens

doi:10.1002/2013ja018870

Cited by 15 publications

(14 citation statements)

References 31 publications

(32 reference statements)

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“…They observed a small region of positive zonal GW momentum flux at 50 • S, 75 • W in an altitude of 30 km. A large eastward GW momentum flux during local winter has been observed by de Wit et al (2017) using SAAMER (Southern Argentina Agile Meteor Radar; 53.7 • S, 67.7 • W) and they explain this with secondary GWs due to stratospheric sources over the Andes mountains in connection with large-amplitude mountain waves breaking in the weak stratospheric winds.…”

Section: Discussionmentioning

confidence: 92%

“…Alexander et al, 2010;Geller et al, 2013). Further enhancement is visible east of the Andes and above all around the Antarctic Peninsula as has been reported, for example, by de la Torre et al (2012) and Hindley et al (2015). In the following we will refer to the run using zonal mean GW weights according to Fig.…”

Section: Stratospheric Gw Fields and Experimental Setupmentioning

confidence: 89%

“…For example, Šácha et al (2015) reported enhanced GW activity over eastern Asia. More frequently, enhanced GW activity has been reported over the Andes and the Antarctic Peninsula (e.g., de la Torre et al, 2012;Faber et al, 2013;Hindley et al, 2015;de Wit et al, 2017;Wright et al, 2017), which affects the middle atmosphere circulation and may even influence the ionosphere (de la Torre et al, 2014;Alexander et al, 2015). In general, GW activity as indicated by E p calculated from GPS RO observations is essentially strong in the tropics and in some areas of the winter hemisphere, whereas it is generally weak in the summer part of the globe.…”

Section: Introductionmentioning

confidence: 97%

“…Note that the GW source must be significant, the propagation conditions up to the measurement zone must be favorable and the waves must stay within the observational filter of the measurement technique in order to detect prominent GW activity. The first climatology of GPS RO E p was presented by Tsuda et al (2000) using GPS-MET satellite observations, but starting with the CHAMP mission (Wickert et al, 2001;Reigber et al, 2002) a much larger and increasing data base has become available (e.g., Ratnam et al, 2004;de la Torre et al, 2006) and high-resolution observations from the six-satellite constellation FORMOSAT-3/COSMIC and additional data sets are available.…”

Section: Introductionmentioning

confidence: 99%

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On the influence of zonal gravity wave distributions on the Southern Hemisphere winter circulation

et al. 2017

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Abstract.A mechanistic global circulation model is used to simulate the Southern Hemisphere stratospheric, mesospheric, and lower thermospheric circulation during austral winter. The model includes a gravity wave (GW) parameterization that is initiated by prescribed 2-D fields of GW parameters in the troposphere. These are based on observations of GW potential energy calculated using GPS radio occultations and show enhanced GW activity east of the Andes and around the Antarctic. In order to detect the influence of an observation-based and thus realistic 2-D GW distribution on the middle atmosphere circulation, we perform model experiments with zonal mean and 2-D GW initialization, and additionally with and without forcing of stationary planetary waves (SPWs) at the lower boundary of the model. As a result, we find additional forcing of SPWs in the stratosphere, a weaker zonal wind jet in the mesosphere, cooling of the mesosphere and warming near the mesopause above the jet. SPW wavenumber 1 (SPW1) amplitudes are generally increased by about 10 % when GWs are introduced being longitudinally dependent. However, at the upper part of the zonal wind jet, SPW1 in zonal wind and GW acceleration are out of phase, which reduces the amplitudes there.

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Section: Discussionmentioning

confidence: 92%

Section: Stratospheric Gw Fields and Experimental Setupmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the influence of zonal gravity wave distributions on the Southern Hemisphere winter circulation

et al. 2017

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“…It has been long known that the thermosphere is routinely disturbed by gravity waves (GWs) propagating from below. In some cases, the sources of strong wave activity in the thermosphere-ionosphere can be traced back to various phenomena in the troposphere, like severe storms (Hung et al, 1979), tsunami (Artru et al, 2005;Garcia et al, 2014;Hickey, 2011), deep convection (Miller et al, 2015), or flow over mountains (de la Torre et al, 2014). Modeling studies have demonstrated that GWs of various scales excited in the troposphere can effectively propagate to the upper thermosphere surviving filtering in the middle atmosphere and damping by exponentially growing with height molecular diffusion and thermal conduction (e.g., Fritts & Lund, 2011;Gavrilov & Kshevetskii, 2013;Heale et al, 2014;).…”

Section: Introductionmentioning

confidence: 99%

Ion Friction and Quantification of the Geomagnetic Influence on Gravity Wave Propagation and Dissipation in the Thermosphere‐Ionosphere

2017

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Motions of neutrals and ions in the thermosphere‐ionosphere (TI) do not, generally, coincide due to the presence of the geomagnetic field and associated electromagnetic forces affecting plasma. Collisions of ions with gravity wave (GW)‐induced motions of neutrals impose damping on the latter. We derive a practical formula for the vertical damping rate of GW harmonics that accounts for the geometry of the geomagnetic field and the direction of GW propagation. The formula can be used in parameterizations of GW effects developed for general circulation models extending from the lower atmosphere into the mesosphere and thermosphere. Vertical damping of GW harmonics by ion‐neutral interactions in the TI depends on the geometry of the geomagnetic field but not the strength of the latter. The ion damping of harmonics propagating in the meridional direction (in the geomagnetic coordinates) maximizes over the poles and reduces to zero over the equator. Waves propagating in the zonal direction are uniformly affected by ions at all latitudes. Accounting for the anisotropy produces changes in the GW drag in the F region of more than 100 m s−1 d−1, cooling/heating rates of more than 15 K d−1, and in GW temperature variance of disturbances by more than 5 K.

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Limb sounders tracking topographic gravity wave activity from the stratosphere to the ionosphere around midlatitude Andes

et al. 2015

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Several studies have shown that the surroundings of the highest Andes mountains at midlatitudes in the Southern Hemisphere exhibit gravity waves (GWs) generated by diverse sources which may traverse the troposphere and then penetrate the upper layers if conditions are favorable. There is a specific latitude band where that mountain range is nearly perfectly aligned with the north‐south direction, which favors the generation of wavefronts parallel to this orientation. This fact may allow an optimization of procedures to identify topographic GW in some of the observations. We analyze data per season to the east and west of these Andes latitudes to find possible significant differences in GW activity between both sectors. GW effects generated by topography and convection are expected essentially on the eastern side. We use satellite data from two different limb sounding methods: the Global Positioning System radio occultation (RO) technique and the Sounding of the Atmosphere using Broadband Emission Radiometry instrument, which are complementary with respect to the height intervals, in order to study the effects of GW from the stratosphere to the ionosphere. Activity becomes quantified by the GW average potential energy in the stratosphere and mesosphere and by the electron density variance content in the ionosphere. Consistent larger GW activity on the eastern sector is observed from the stratosphere to the ionosphere (night values). However, this fact remains statistically significant at the 90% significance level only during winter, when GWs generated by topography dominate the eastern sector. On the contrary, it is usually assumed that orographic GWs have nearly zero horizontal phase speed and will therefore probably be filtered at some height in the neutral atmosphere. However, this scheme relies on the assumption that the wind is uniform and constant. Our results also suggest that it is advisable to separate night and day cases to study GWs in the ionosphere, as it is more difficult to find significant statistical differences during daytime. This may happen because perturbations induced by GWs during daytime are more likely to occur in a disturbed environment that may hinder the identification of the waves.

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Wave activity at ionospheric heights above the Andes Mountains detected from FORMOSAT‐3/COSMIC GPS radio occultation data

Cited by 15 publications

References 31 publications

On the influence of zonal gravity wave distributions on the Southern Hemisphere winter circulation

On the influence of zonal gravity wave distributions on the Southern Hemisphere winter circulation

Ion Friction and Quantification of the Geomagnetic Influence on Gravity Wave Propagation and Dissipation in the Thermosphere‐Ionosphere

Limb sounders tracking topographic gravity wave activity from the stratosphere to the ionosphere around midlatitude Andes

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