Numerical simulations of gravity wave modulation of midlatitude sporadic E layers

Huang, Chao-Song; Kelley, M. C.

doi:10.1029/96ja02327

Cited by 38 publications

(46 citation statements)

References 26 publications

(13 reference statements)

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“…Yamamoto et al, 1991;Ogawa et al, 1995Ogawa et al, , 2002, which suggests that these fluctuations are invoked by AGWs and/or polarization electric fields in an E s (Huang and Kelley, 1996;Horinouchi et al, 2002;Horinouchi, 2004;Yokoyama et al, 2004bYokoyama et al, , 2005. Strong electric field fluctuations were actually found from the rocket flights during SEEK-1 (Pfaff et al, 1998) and SEEK-2 (Wakabayashi et al, 2005).…”

Section: Introductionmentioning

confidence: 83%

The first coordinated observations of mid-latitude E-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow

et al. 2005

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Abstract. We present the first coordinated observations of quasi-periodic (QP) radar echoes from sporadic-E (E s ) field-aligned irregularities (FAIs), OI 557.7-nm airglow, and neutral winds in a common volume over Shigaraki, Japan (34.9 • N, 136.1 • E) on the night of 5 August 2002 during the SEEK-2 campaign. QP echo altitudes of 90-110 km were lower than usual by 10 km, enabling us to make a detailed comparison among QP echoes, airglow intensity, and neutral wind at around 96 km altitude. Eastward movement of the QP echo regions is consistent with the motions of neutral winds, airglow structures, and FAIs, suggesting that the electrodynamics of E s -layers is fundamentally controlled by the neutral atmospheric dynamics. During the QP echo event, the echo altitudes clearly went up (down) in harmony with an airglow enhancement (subsidence) that also moved to the east. This fact suggests that the eastward-moving enhanced airglow region included an upward (downward) component of neutral winds to raise (lower) the altitude of the windshear node responsible for the E s formation. The airglow intensity, echo intensity, and Doppler velocity of FAIs at around 96 km altitude fluctuated with periods from 10 min to 1 h, indicating that these parameters were modulated with short-period atmospheric disturbances. Some QP echo regions below 100 km altitude contained small-scale QP structures in which very strong neutral winds exceeding 100 m/s existed. The results are compared with recent observations, theories, and simulations of QP echoes.

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Section: Introductionmentioning

confidence: 83%

The first coordinated observations of mid-latitude E-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow

et al. 2005

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“…The data presented here support the idea proposed by Woodman et al (1991) of gravity wave modulation of Es-layers, but the large periods observed cannot support a resonance mechanism. In a recent numerical study Huang and Kelley (1996) have shown that spatial resonance is not required to obtain signi®cant modulation of the height of an Es-layer, but their work should be extended to longer-period waves to account for our observations.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Decameter mid-latitude sporadic-E irregularities in relation with gravity waves

Bourdillon¹,

Lefur²,

Haldoupis

et al. 1997

Ann Geophysicae

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Abstract. HF radar observations of mid-latitude sporadic-E irregularities carried out with the Valensole radar in South France are compared with simultaneous ionosonde measurements underneath the irregularity zones. In a previous study of Valensole radar data, it has been shown that HF backscatter from the night-time mid-latitude E region is usually associated with largescale wave-like modulations. To obtain more information on the geophysical conditions prevailing during backscatter events, a new experiment was performed which also included a vertical ionosonde beneath the scattering region. The data to be presented here are from two periods when radar scattering appeared simultaneously with large variations in the virtual height and the Doppler velocity of F-layer re¯ected echoes measured with the vertical ionosonde, indicating very clearly the passage of atmospheric gravity waves (AGWs). The e ect of the atmospheric waves on the sporadic-E layer is not always as marked as it is in the F region. In the ®rst event, the passage of the AGWs is accompanied by an upward followed by a downward movement of the Es-layer. The apparent descending movement of the Es-layer from 135 to 110 km in less than 10 min corresponded to a positive (downward) Doppler velocity of 35 m/s measured by the vertical ionosonde, and was accompanied by a range variation in the radar scattering region with a negative rate of about 90±110 m/s. In the second event, the Es-layer is not as strongly disturbed as in the previous one, but, nevertheless, the range variations of the scattering region can still be associated with height¯uctuations of the Es-layer.

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“…Substituting (5) -(9) into (1) -(4), similar to the procedure used in the simulations of gravity wave modulation of midlatitude sporadic E layers [Huang and Kelley, 1996b], we obtain the coupled equations for •p and N and then solve them numerically. We assume that the …”

Section: Model Equationsmentioning

confidence: 99%

Numerical simulations of midlatitude ionospheric perturbations produced by gravity waves

Huang¹,

Sofko²,

Kelley³

1998

J. Geophys. Res.

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Abstract. We have used a computer simulation to study ionospheric perturbations produced by gravity waves in the midlatitude F region. The change of amplitude and vertical wavelength of gravity waves with height is taken into account. The presence of plasma diffusion causes the height profile of the wave-induced ionospheric perturbations to be quite different from the forcing gravity waves but does not lead to field alignment of the ionospheric structures. The attenuation of the amplitude of gravity waves with height does not cause the upturning of the phase surfaces of the wave-induced ionospheric perturbations. The upturning of the phase surface of ionospheric perturbations produced by a gravity wave is caused solely by the increase with height of the vertical wavelength of the wave, regardless of whether the gravity wave amplitude increases or decreases with height. The amplitude of gravity-wave-induced ionospheric perturbations is smaller at higher altitudes than at lower altitudes because of the presence of plasma diffusion even if the gravity waves have larger amplitudes at high altitudes. Strong ionospheric density gradients can be produced in the altitude range of 200-400 km. The numerical results are compared with the values predicted by theory. If the gravity waves are uniform in space, the theory gives reasonable estimates of the relative ionospheric density fluctuations. Even when plasma diffusion is present, deviation of the numerical results from the theory is generally <10%. However, if a more realistic gravity wave model in which the amplitude and wavelength vary with height is used in the simulations, significant differences, as much as 50% for daytime ionospheric perturbations, arise between the numerical and theoretical results.

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Numerical simulations of gravity wave modulation of midlatitude sporadic E layers

Cited by 38 publications

References 26 publications

The first coordinated observations of mid-latitude <i>E</i>-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow

The first coordinated observations of mid-latitude <i>E</i>-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow

Decameter mid-latitude sporadic-E irregularities in relation with gravity waves

Numerical simulations of midlatitude ionospheric perturbations produced by gravity waves

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Numerical simulations of gravity wave modulation of midlatitude sporadic E layers

Cited by 38 publications

References 26 publications

The first coordinated observations of mid-latitude &lt;i&gt;E&lt;/i&gt;-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow

The first coordinated observations of mid-latitude &lt;i&gt;E&lt;/i&gt;-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow

Decameter mid-latitude sporadic-E irregularities in relation with gravity waves

Numerical simulations of midlatitude ionospheric perturbations produced by gravity waves

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The first coordinated observations of mid-latitude <i>E</i>-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow

The first coordinated observations of mid-latitude <i>E</i>-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow