Continuous quasiperiodic thermospheric waves over Arecibo

Livneh, D. J.; Şeker, Ilgın; Djuth, F. T.; Mathews, J. D.

doi:10.1029/2006ja012225

Cited by 44 publications

(64 citation statements)

References 51 publications

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“…These constraints are less severe for GWs arising at higher altitudes, however, because of the increasing temperatures and scale heights in the thermosphere. Thus we expect that primary sources at much higher altitudes, such as auroral excitation , and references cited above), and secondary sources such as local body forces (Vadas andFritts, 2001, 2002) must also excite GWs at substantially larger spatial scales that can penetrate, in turn, to even higher altitudes, as observed by various authors (Oliver et al, 1997;Djuth et al, 1997Djuth et al, , 2004Livneh et al, 2007). We expect these GWs to have very small initial amplitudes and momentum fluxes, as for the larger scales excited by lower atmosphere sources, but to also experience dramatic amplification factors in propagating to altitudes of 300 km and above.…”

Section: Variations Of Gw Momentum Fluxes and Body Forces With Altitudementioning

confidence: 96%

“…(1) yields the usual inviscid anelastic dispersion relation of Marks and Eckermann (1995). Temperature, density, and wind profiles employed for our study are shown in Fig.…”

Section: Anelastic Viscous Dispersion Relation and Assumptionsmentioning

confidence: 99%

“…Other motions believed to arise at lower altitudes typically have phase speeds less than 250 m/s Jones, 1986, 1987;Crowley et al, 1987;Ogawa et al, 1987). GW periods were found to vary with altitude, with smaller periods (∼20 to 60 min) more prevalent in the lower thermosphere and longer periods (∼1 h or longer) accounting for the largest fluctuations at greater altitudes (Thome and Rao, 1969;Hearn and Yeh, 1977;Hung and Kuo, 1978;Livneh et al, 2007). Vertical wavelengths were also found to vary with altitude, ranging from a few or 10s of km in the lower thermosphere to ∼100 to 300 km significantly above (Oliver et al, 1997;Djuth et al, 1997Djuth et al, , 2004Livneh et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…GW periods were found to vary with altitude, with smaller periods (∼20 to 60 min) more prevalent in the lower thermosphere and longer periods (∼1 h or longer) accounting for the largest fluctuations at greater altitudes (Thome and Rao, 1969;Hearn and Yeh, 1977;Hung and Kuo, 1978;Livneh et al, 2007). Vertical wavelengths were also found to vary with altitude, ranging from a few or 10s of km in the lower thermosphere to ∼100 to 300 km significantly above (Oliver et al, 1997;Djuth et al, 1997Djuth et al, , 2004Livneh et al, 2007). Typical horizontal wavelengths also vary with altitude, but apparently to a much smaller degree, being most often in the range of ∼130 to 500 km (Thome and Rao, 1969;Hearn and Yeh, 1977;Samson et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

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Gravity wave penetration into the thermosphere: sensitivity to solar cycle variations and mean winds

2008

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Abstract. We previously considered various aspects of gravity wave penetration and effects at mesospheric and thermospheric altitudes, including propagation, viscous effects on wave structure, characteristics, and damping, local body forcing, responses to solar cycle temperature variations, and filtering by mean winds. Several of these efforts focused on gravity waves arising from deep convection or in situ body forcing accompanying wave dissipation. Here we generalize these results to a broad range of gravity wave phase speeds, spatial scales, and intrinsic frequencies in order to address all of the major gravity wave sources in the lower atmosphere potentially impacting the thermosphere. We show how penetration altitudes depend on gravity wave phase speed, horizontal and vertical wavelengths, and observed frequencies for a range of thermospheric temperatures spanning realistic solar conditions and winds spanning reasonable mean and tidal amplitudes. Our results emphasize that independent of gravity wave source, thermospheric temperature, and filtering conditions, those gravity waves that penetrate to the highest altitudes have increasing vertical wavelengths and decreasing intrinsic frequencies with increasing altitude. The spatial scales at the highest altitudes at which gravity wave perturbations are observed are inevitably horizontal wavelengths of ∼150 to 1000 km and vertical wavelengths of ∼150 to 500 km or more, with the larger horizontal scales only becoming important for the stronger Doppler-shifting conditions. Observed and intrinsic periods are typically ∼10 to 60 min and ∼10 to 30 min, respectively, with the intrinsic periods shorter at the highest altitudes because of preferential penetration of GWs that are up-shifted in frequency by thermospheric winds.

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Section: Variations Of Gw Momentum Fluxes and Body Forces With Altitudementioning

confidence: 96%

“…(1) yields the usual inviscid anelastic dispersion relation of Marks and Eckermann (1995). Temperature, density, and wind profiles employed for our study are shown in Fig.…”

Section: Anelastic Viscous Dispersion Relation and Assumptionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Gravity wave penetration into the thermosphere: sensitivity to solar cycle variations and mean winds

2008

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“…Djuth et al (2004) suggest that, near Arecibo, there is a continuum of gravity waves in the thermosphere, and that these showed "sets" of waves separated typically by 20-60 min. Livneh et al (2007) used incoherent scatter radar at Arecibo Observatory to observe quasi-coherent continuous waves with periods of ∼1 h in the ionosphere. These are also typical periods of auroral AGWs (Bristow and Greenwald, 1997) that are likely generated by pulsed ionospheric convection (Prikryl et al, 2005) virtually continuously and sometimes observed as TIDs by SuperDARN He et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

The influence of solar wind on extratropical cyclones – Part 2: A link mediated by auroral atmospheric gravity waves?

2009

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Abstract. Cases of mesoscale cloud bands in extratropical cyclones are observed a few hours after atmospheric gravity waves (AGWs) are launched from the auroral ionosphere. It is suggested that the solar-wind-generated auroral AGWs contribute to processes that release instabilities and initiate slantwise convection thus leading to cloud bands and growth of extratropical cyclones. Also, if the AGWs are ducted to low latitudes, they could influence the development of tropical cyclones. The gravity-wave-induced vertical lift may modulate the slantwise convection by releasing the moist symmetric instability at near-threshold conditions in the warm frontal zone of extratropical cyclones. Latent heat release associated with the mesoscale slantwise convection has been linked to explosive cyclogenesis and severe weather. The circumstantial and statistical evidence of the solar wind influence on extratropical cyclones is further supported by a statistical analysis of high-level clouds (<440 mb) extracted from the International Satellite Cloud Climatology Project (ISCCP) D1 dataset. A statistically significant response of the high-level cloud area index (HCAI) to fast solar wind from coronal holes is found in mid-tohigh latitudes during autumn-winter and in low latitudes during spring-summer. In the extratropics, this response of the HCAI to solar wind forcing is consistent with the effect on tropospheric vorticity found by Wilcox et al. (1974) and verified by Prikryl et al. (2009). In the tropics, the observed HCAI response, namely a decrease in HCAI at the arrival of solar wind stream followed by an increase a few days later, is similar to that in the northern and southern mid-to-high latitudes. The amplitude of the response nearly doubles for stream interfaces associated with the interplanetary magnetic field B Z component shifting southward. When the IMF B Z after the stream interface shifts northward, the autumn-winter Correspondence to: P. Prikryl (paul.prikryl@crc.ca) effect weakens or shifts to lower (mid) latitudes and no statistically significant response is found at low latitudes in springsummer. The observed effect persists through years of low and high volcanic aerosol loading. The similarity of the response in mid-to-high and low latitudes, the lack of dependence upon aerosol loading, and the enhanced amplitude of the effect when IMF B Z component shifts southward, favor the proposed AGW link over the atmospheric electric circuit (AEC) mechanism (Tinsley et al., 1994). The latter requires the presence of stratospheric aerosols for a significant effect and should produce negative and positive cloud anomalies in mid-to-high and low latitudes, respectively. However, if the requirement of aerosols for the AEC mechanism can be relaxed, the AGW and AEC mechanisms should work in synergy at least in mid-to-high latitudes.

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Horizontal parameters of daytime thermospheric gravity waves and E region neutral winds over Puerto Rico

et al. 2014

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We report on the electron density perturbation amplitudes, periods (up to 60 min), horizontal and vertical wavelengths, phase speeds, and propagation directions of daytime traveling ionospheric disturbances (TIDs) from 115 to 300 km altitude using dual‐beam experiments at the Arecibo Observatory (AO), Puerto Rico. As in previous studies, we find a near continuum of waves above the AO. While the TIDs propagate in nearly all directions except purely westward, we find that most propagate southward southeastward. We find that TID amplitudes increase nearly exponentially with increasing period, although with a much smaller slope for periods >30 min. TID amplitudes peak on the bottomside of the F region. Typical vertical wavelengths increase from less than 50 km at low altitudes to ∼100–300 km. Horizontal wavelengths increase from ∼70–100 km to ∼150–500 km over the same altitude range. Median vertical wavelengths, horizontal wavelengths, and periods increase with altitude up to z∼<225 km and are approximately constant at higher altitudes. Horizontal phase speeds are >100–150 m/s. We also measure the E region horizontal neutral winds and find that they peak at ∼150 m/s near z∼105 km in the middle of the day. Wave phase speeds are in general greater than these ambient winds. In addition, by tracing individual wave packets vertically in altitude, we find that a packet's vertical wavelength generally peaks near the altitude where its inferred ion velocity amplitude is maximum. The vertical wavelength generally decreases above this altitude, an observation that is consistent with gravity wave packet theory.

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Continuous quasiperiodic thermospheric waves over Arecibo

Cited by 44 publications

References 51 publications

Gravity wave penetration into the thermosphere: sensitivity to solar cycle variations and mean winds

Gravity wave penetration into the thermosphere: sensitivity to solar cycle variations and mean winds

The influence of solar wind on extratropical cyclones – Part 2: A link mediated by auroral atmospheric gravity waves?

Horizontal parameters of daytime thermospheric gravity waves and E region neutral winds over Puerto Rico

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