Application of the Dopplionogram to Doppler‐sorted interferometry measurements of ionospheric drift velocity

Parkinson, M. L.; Breed, A. M.; Dyson, P. L.; Morris, R. J.

doi:10.1029/1999rs900029

Cited by 10 publications

(9 citation statements)

References 16 publications

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“…Some of the observed activity may have been driven by lobecell merging which occurs on open field lines poleward of the cusp when the IMF is northward [Crooker and Rich, 1993]. In this section we make use of methods of analyzing and displaying digisonde data described by Parkinson et al [1999].…”

Section: Signatures Of a Major Cusp Event February 16 1996mentioning

confidence: 99%

Signatures of the ionospheric cusp in digital ionosonde measurements of plasma drift above Casey, Antarctica

Parkinson¹,

Breed²,

Dyson³

et al. 1999

J. Geophys. Res.

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Abstract. Signatures of the ionospheric cusp in HF digital ionosonde measurements of plasma drift made at the polar cap station Casey, Antarctica (-80.8 ø geomagnetic latitude), are investigated. Measurements recorded during the campaign interval February 13-17, 1996, are considered in this case study because the summer dipole tilt effect, and an interplanetary magnetic field (IMF) northward condition on February 16, were favorable for the detection of the cusp at a higher than usual latitude. On February 14 and 15 the magnitude of the IMF was about 4-6 nT, and the station probably passed just poleward of the cusp. The most general signatures of the cusp were enhanced electric field and electric field turbulence shown by increased drift velocity and velocity scatter in the convection throat, respectively. Broadband, unstructured fluctuations in the geomagnetic field measured by magnetometers near to noon are well known to be a signature of cusp currents and were associated with the intervals of enhanced convection turbulence. A major cusp event occurred above Casey on February 16, when the magnitude of the IMF increased from about 5 to > 10 nT. Cusp signatures during this event included the drift velocity surging to large values just before and after an interval during which the F region echoes were lost because of an absence of F region ionization and the formation of electron density patches. The loss of echoes was only partly explained by increased absorption and scatter of the transmitted radio waves. Although the spectral width of Doppler peaks increased, this, by itself, was not a unique signature of the cusp because the obliquity of echoes also controlled the spectral width in our near-vertical interferometry. However, signatures of the cusp were easily recognized in digisonde data, and the cusp's location and dynamics can be monitored using digisondes.

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Section: Signatures Of a Major Cusp Event February 16 1996mentioning

confidence: 99%

Signatures of the ionospheric cusp in digital ionosonde measurements of plasma drift above Casey, Antarctica

Parkinson¹,

Breed²,

Dyson³

et al. 1999

J. Geophys. Res.

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“…In general, there are two basic methods used to obtain the Doppler frequency of HF echoes by digital ionosonde. With the first method, the ionospheric Doppler is calculated by the Fourier Transform of the channel impulse response (CIR) of the ionospheric channel [ Goutelard et al , 1994; Parkinson et al , 1999; Reinisch , 1996]. However, in order to get high resolution in Doppler, the coherent integration time (CIT) for sounding should be long enough and may exceed the stable duration of the plasma.…”

Section: Introductionmentioning

confidence: 99%

Ionospheric Doppler and echo phase measured by the Wuhan Ionospheric Oblique Backscattering Sounding System

2007

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[1] Wuhan Ionospheric Oblique Backscattering Sounding System (WIOBSS) is a highfrequency (HF) sky wave over-the-horizon radar developed for ionospheric research and HF channel management. This radar, located in Wuhan (30.35°N, 114.33°E) has been under construction by the Ionosphere Lab of Wuhan University since 2002. WIOBSS uses long coded pulses and pulse compression to achieve good sensitivity and measures the bitemporal ionospheric response, channel scattering function, and phase of echoes simultaneously and then displays the processed data as ionograms and Dopplionograms in real time. Bitemporal ionospheric response is a matrix composed of the ionospheric transmission function with delay and time variables, while the scattering function shows the spectrum of the received signals as a function of the delay and Doppler coordinates, and is obtained by the Fourier Transform of the bitemporal ionospheric response over the time variable. The application of pulse compression and coherent integration allows WIOBSS to measure ionospheric Doppler with high resolution and very low power. A method is developed to get phase data directly from the bitemporal ionospheric response. The measured phase is strung in a series and then divided into linear and nonlinear components. The angular frequency of the linear component is in direct proportion to ionospheric Doppler velocity while the fluctuation of the nonlinear component includes the information of Doppler velocity spread. The phase method based on pulse impression is able to obtain the statistic Doppler information from weak backscattered echoes in short detection time.

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“…The latter technique is also known as Doppler sorted interferometry (DSI) (e.g. Parkinson et al, 1999). For the measurements analysed in this paper, the DPS-4 recorded ionograms by scanning in frequency for less than 2 min once every 10 min.…”

Section: Instrument and Databasementioning

confidence: 99%

“…This gave a Doppler resolution of 24.4 mHz ( T f =1) and a corresponding Nyquist frequency of ±1.5625 Hz. More details about the Bundoora DPS-4 and its operating modes have been given by Parkinson et al (1999Parkinson et al ( , 2001.…”

Section: Instrument and Databasementioning

confidence: 99%

Solar and geomagnetic activity effects on mid-latitude F-region electric fields

et al. 2008

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Abstract. Diurnal patterns of average F-region ionospheric drift (electric field) and their dependence on solar and geomagnetic activity have been defined using digital ionosonde Doppler measurements recorded at a southern mid-latitude station (Bundoora 145.1 • E, 37.7 • S geographic, 49 • S magnetic). A unique database consisting of 300 907 drift velocities was compiled, mostly using one specific mode of operation throughout 1632 days of a 5-year interval (1999)(2000)(2001)(2002)(2003). The velocity magnitudes were generally larger during the night than day, except during the winter months (JuneAugust), when daytime velocities were enhanced. Of all years, the largest drifts tended to occur during the high speed solar wind streams of 2003. Diurnal patterns in the average quiet time (AE<75 nT) meridional drifts (zonal electric field) peaked at up to ∼6 m s −1 poleward (0.3 mV m −1 eastward) at 03:30 LST, reversing in direction at ∼08:30 LST, and gradually reaching ∼10 m s −1 equatorward at ∼13:30 LST. The quiet time zonal drifts (meridional electric fields) displayed a clear diurnal pattern with peak eastward flows of ∼10 m s −1 (0.52 mV m −1 equatorward) at 09:30 LST and peak westward flows around midnight of ∼18 m s −1 (0.95 mV m −1 poleward). As the AE index increased, the westward drifts increased in amplitude and they extended over a greater fraction of the day. The perturbation drifts changed in a similar way with decreasing D st except the daytime equatorward flows strengthened with increasing AE index, whereas they became weak for D st <−60 nT. The responses in all velocity components to changing solar flux values were small, but net poleward perturbations during the day were associated with large solar flux values (>192×10 −22 W m −2 Hz −1 ). These results help to more fully quantify the response of the midlatitude ionosphere to changing solar and geomagnetic conditions, as required to refine empirical and theoretical models of mid-latitude electric fields.Correspondence to:

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Application of the Dopplionogram to Doppler‐sorted interferometry measurements of ionospheric drift velocity

Cited by 10 publications

References 16 publications

Signatures of the ionospheric cusp in digital ionosonde measurements of plasma drift above Casey, Antarctica

Signatures of the ionospheric cusp in digital ionosonde measurements of plasma drift above Casey, Antarctica

Ionospheric Doppler and echo phase measured by the Wuhan Ionospheric Oblique Backscattering Sounding System

Solar and geomagnetic activity effects on mid-latitude F-region electric fields

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