HF Doppler observations of medium-scale travelling ionospheric disturbances at mid-latitudes

Waldock, J. A.; Jones, T. B.

doi:10.1016/0021-9169(86)90099-1

Cited by 93 publications

(82 citation statements)

References 28 publications

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“…This is consistent with results of Fig. 4 Diurnal dependence of the MSTID occurrence rates for the horizontal phase velocity (a), period (b), horizontal wavelength (c), and relative amplitude (d) Waldock and Jones (1986) and can be related with the increased HF reflection height during the nighttime in comparison with daytime. Velocity of GW propagating upward is expected to increase with altitude to compensate for the decreasing atmospheric density (Hines 1960).…”

Section: Resultssupporting

confidence: 91%

“…This results in the appearance of a certain diurnal pattern of the observed MSTID azimuths. Many researchers have reported observational evidences of this effect (Kalikhman 1980;Waldock and Jones 1986;Afraimovich et al 1999;Kotake et al 2007). Kalikhman (1980) has presented a statistical study based on Doppler and arrival angle data obtained by the F2 layer vertical sounding from 1975 to 1976 at Irkutsk.…”

Section: Resultsmentioning

confidence: 99%

“…He showed that the direction of MSTID motion during daytime agrees well with the thermospheric wind direction and is oriented opposite to it. Waldock and Jones (1986) observed the MSTIDs from 1972 to 1975 at Leicester by means of an HF Doppler technique and found that the wave azimuth rotates clockwise through 360°in 24 h. However, the direction of disturbance motion is displaced from the anti-wind direction and is located at an azimuth of 130°-140°rela-tive to the wind. Afraimovich et al (1999) analyzed the annual data from the transionospheric radio interferometer that measured the parameters of the radio signal at 136 MHz from the ETS 2 geostationary satellite.…”

Section: Resultsmentioning

confidence: 99%

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Statistical characteristics of medium-scale traveling ionospheric disturbances revealed from the Hokkaido East and Ekaterinburg HF radar data

et al. 2016

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We present a statistical study of medium-scale traveling ionospheric disturbances (MSTIDs) using the Hokkaido East (43.53°N, 143.61°E) and Ekaterinburg (56.42°N, 58.53°E) high-frequency (HF) radar data. Radar datasets are available from 2007 to 2014 for the Hokkaido and from 2013 to 2014 for the Ekaterinburg radar. In the case of the Hokkaido East radar, we have utilized the elevation angle information to study the MSTIDs propagating at the heights of the E and F ionospheric regions separately. We have analyzed the diurnal and seasonal behavior of the following medium-scale traveling ionospheric disturbance (MSTID) parameters: propagation direction, apparent horizontal velocity and wavelength, period, and relative amplitude. The F region MSTID azimuthal patterns were observed to be quite similar by the two radars. The E region northwestward MSTIDs (from 280°to 320°) were typical of summer daytime. Comparison with the horizontal wind model (HWM07) has showed that the dominant MSTID propagation directions match the anti-wind direction well, at least during sunlight hours. We have also found that the wavelength and period tend to decrease with an increase in solar activity. On the contrary, the relative amplitude increases with an increase in solar activity. Moreover, the relative amplitude tends to increase with increasing auroral electrojet (AE) index, as do the wavelength and velocity.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Statistical characteristics of medium-scale traveling ionospheric disturbances revealed from the Hokkaido East and Ekaterinburg HF radar data

et al. 2016

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“…Doppler shifts may reduce the vertical scales of gravity waves that propagate parallel to the wind flow, leading to more rapid dissipation by viscosity, and also modulating the effectiveness of their perturbations of the ionospheric densities. Many studies have observed this effect by looking at MSTID measurements along with models of thermospheric wind velocities [Waldock and Jones, 1986;Bristow et al, 1996;Afraimovich et al, 1999;Ishida et al, 2008]. We tested our observations against this hypothesis by using the horizontal wind model 2007 (HWM07), which provides an empirical, statistical model of the Earth's atmospheric zonal and meridional winds from 0 to 500 km altitude [Drob et al, 2008].…”

Section: Local Time Dependence Of Mstidsmentioning

confidence: 97%

“…To first order, thermospheric neutral winds may modulate or filter AGWs (that may underlie the observed MSTIDs) when they propagate parallel to the flow [Waldock and Jones, 1986]. Doppler shifts may reduce the vertical scales of gravity waves that propagate parallel to the wind flow, leading to more rapid dissipation by viscosity, and also modulating the effectiveness of their perturbations of the ionospheric densities.…”

Section: Local Time Dependence Of Mstidsmentioning

confidence: 99%

Climatology of medium‐scale traveling ionospheric disturbances observed by the midlatitude Blackstone SuperDARN radar

et al. 2014

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Horizontal velocities ranged from 50 to 250 m s −1 with a distribution maximum between 100 and 150 m s −1 . Horizontal wavelengths ranged from 100 to 500 km with a distribution peak at 250 km, and periods between 23 and 60 min, suggesting that the MSTIDs may be consistent with thermospheric gravity waves. A local time (LT) dependence was observed such that the dominant (southeastward) population decreased in number as the day progressed until a late afternoon increase. The secondary (northwestward) population appeared only in the afternoon, possibly indicative of neutral wind effects or variability of sources. LT dependence was not observed in other parameters. Possible solar-geomagnetic and tropospheric MSTID sources were considered. The auroral electrojet (AE) index showed a correlation with MSTID statistics. Reverse ray tracing with the HINDGRATS model indicates that the dominant population has source regions over the Great Lakes and near the geomagnetic cusp, while the secondary population source region is 100 km above the Atlantic Ocean east of the Carolinas. This suggests that the dominant population may come from a region favorable to either tropospheric or geomagnetic sources, while the secondary population originates from a region favorable to secondary waves generated via lower atmospheric convection.

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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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HF Doppler observations of medium-scale travelling ionospheric disturbances at mid-latitudes

Cited by 93 publications

References 28 publications

Statistical characteristics of medium-scale traveling ionospheric disturbances revealed from the Hokkaido East and Ekaterinburg HF radar data

Statistical characteristics of medium-scale traveling ionospheric disturbances revealed from the Hokkaido East and Ekaterinburg HF radar data

Climatology of medium‐scale traveling ionospheric disturbances observed by the midlatitude Blackstone SuperDARN radar

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

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