Comparison between manual scaling and Autoscala automatic scaling applied to Sodankylä Geophysical Observatory ionograms

Enell, Carl‐Fredrik; Kozlovsky, Alexander; Turunen, T.; Ulich, Thomas; Välitalo, S.; Scotto, Carlo; Pezzopane, Michael

doi:10.5194/gi-5-53-2016

Cited by 23 publications

(16 citation statements)

References 16 publications

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“…The present ionosonde, called Alpha Wolf, is a frequency-modulated continuous wave chirp sounder developed at SGO. Details of the instrument have been described in Enell et al (2016). Sounding is made once a minute, and each sweep lasts for 30 s, during which the transmitted signal frequency is linearly increased from 0.5 to 16 MHz.…”

Section: Meteor-induced Traces In the Ionosonde Datamentioning

confidence: 99%

Multi‐Instrumental Observations of Nonunderdense Meteor Trails

Kozlovsky¹,

Шалимов

Kero

et al. 2018

JGR Space Physics

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Using data from the Sodankylä Geophysical Observatory (67°22′N, 26°38′E, Finland) meteor camera from the whole year 2015, we identified and investigated 28 optical meteors with accompanying ionization trails unambiguously detected by the Sodankylä Geophysical Observatory ionosonde, which sounded the ionosphere once per minute with frequency rising from 0.5 to 16 MHz. These ionosonde reflections were obtained from heights around 90 km. The electron line densities of the trails were found to be between 1014 and 1016 m−1, which characterize the trails as nonunderdense (i.e., transitional and overdense). The ionosonde reflections were observed for a few minutes, with decreasing maximal frequency of the return. During the first 250 s, for the trails with initial line density about (2–3) · 1015 m−1 the return frequency decreased with time corresponding to the diffusional expansion of cylindrical meteor trails, that is, f ∝ t−γ, where the exponent γ = 0.5, whereas less dense trails decayed slower (γ ≈ 0.2) and more dense trails decayed faster (γ ≈ 1). In many cases the meteor events were accompanied by nonspecular long‐lived detections using a colocated all‐sky interferometric meteor radar with operating frequency 36.9 MHz. As a rule the meteor radar echo durations were longer than expected from diffusional expansion of cylindrical meteor trails and their amplitudes were highly variable. We suggest that the slower frequency decrease of the ionosonde echoes and the nonspecular long‐lived meteor radar echoes might be associated with the presence of meteoric dust.

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Section: Meteor-induced Traces In the Ionosonde Datamentioning

confidence: 99%

Multi‐Instrumental Observations of Nonunderdense Meteor Trails

Kozlovsky¹,

Шалимов

Kero

et al. 2018

JGR Space Physics

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“…Several attempts had been made to verify ionogram autoscaling system quality (Reinisch et al, 2005;Enell et al, 2016;Pezzopane et al, 2017). Early comparisons between manual and automatic scaled ionospheric parameters revealed limitations in ARTIST system performance due to the absence of quality metrics (Gilbert and Smith, 1988).…”

Section: Ionogram Qualitymentioning

confidence: 99%

“…Ionosonde data scaled by ARTIST 5 have a quality metric called the confidence score (CS). Such a metric is based on quality criteria supported by concepts of ionogram interpretation and algorithms that specify the uncertainty and confidence of scaled results (Galkin et al, 2013). The CS metric includes quality checking solutions introduced by confidence calculation schemes developed since the late 1980s: the auto-scaling confidence level (ACL) quality flag, the twodigit confidence level (C-Level), and the QualScan quality control (McNamara, 2006;Galkin et al, 2013).…”

Section: Ionogram Qualitymentioning

confidence: 99%

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Ionosonde total electron content evaluation using International Global Navigation Satellite System Service data

et al. 2020

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Abstract. In this work, a period of 2 years (2016–2017) of ionospheric total electron content (ITEC) from ionosondes operating in Brazil is compared to the International GNSS (Global Navigation Satellite System) Service (IGS) vertical total electron content (vTEC) data. Sounding instruments from the National Institute for Space Research (INPE) provided the ionograms used, which were filtered based on confidence score (CS) and C-Level flag evaluation. Differences between vTEC from IGS maps and ionosonde TEC were accumulated in terms of root mean squared error (RMSE). As expected, we noticed that the ITEC values provided by ionosondes are systematically underestimated, which is attributed to a limitation in the electron density modeling for the ionogram topside that considers a fixed scale height, which makes density values decay too rapidly above ∼800 km, while IGS takes in account electron density from GNSS stations up to the satellite network orbits. The topside density profiles covering the plasmasphere were re-modeled using two different approaches: an optimization of the adapted α-Chapman exponential decay that includes a transition function between the F2 layer and plasmasphere and a corrected version of the NeQuick topside formulation. The electron density integration height was extended to 20 000 km to compute TEC. Chapman parameters for the F2 layer were extracted from each ionogram, and the plasmaspheric scale height was set to 10 000 km. A criterion to optimize the proportionality coefficient used to calculate the plasmaspheric basis density was introduced in this work. The NeQuick variable scale height was calculated using empirical parameters determined with data from Swarm satellites. The mean RMSE for the whole period using adapted α-Chapman optimization reached a minimum of 5.32 TECU, that is, 23 % lower than initial ITEC errors, while for the NeQuick topside formulation the error was reduced by 27 %.

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“…This is a standard Lowell Digisonde (http://www.digisonde.com) making vertical ionospheric sounding once in 15 min (Hall & Hansen, ). Additionally, data from the SGO ionosonde, a frequency‐modulated continuous wave chirp sounder developed at SGO (Enell et al, ), were used. Sounding is made once a minute, and each sweep lasts for 30 s, during which the transmitted signal frequency is linearly increased from 0.5 to 16 MHz.…”

Section: Instruments and Datamentioning

confidence: 99%

Ground Echoes Observed by the Meteor Radar and High‐Speed Auroral Observations in the Substorm Growth Phase

et al. 2019

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Multi‐instrument observations by a meteor radar (MR), auroral cameras, ionosondes, and ground magnetometers were made in Northern Europe at auroral latitudes (between 64° and 72° corrected geomagnetic latitude) at 22–24 magnetic local time in the substorm growth phase. The southward drifting growth phase auroral arc was associated with enhanced electron density up to 2⋅1012 m‐3 (corresponding to a plasma frequency, foEs of about 13 MHz) at about 110‐km altitude. Such an enhanced E layer electron density caused bending toward the ground of the MR radio waves transmitted at a frequency, fr, of 36.9 MHz and at low elevation (el. < 25°), such that the radar received ground echoes characterized by a near‐zero Doppler shift. The amplitude of the echoes was modulated at a frequency of a few hertz, and a similar modulation was found in the auroral luminosity at 427.8 nm near the location of the bending of MR radio waves. The modulation was due to irregular (random) fluctuations of auroral precipitation. Although such a few‐hertz variation of the auroral precipitation cannot produce more than 1% modulation of the ionospheric electron density, even such a small modulation can lead to 50% modulation of the MR ground scatter provided foEs ≈ fr sin (el.). The ionosonde and MR data provide evidence that this condition was satisfied in the present case. Due to a high‐frequency (>2 Hz) amplitude modulation of the ground scatter, the MR erroneously accepts such signals as echoes from meteor trails.

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Comparison between manual scaling and Autoscala automatic scaling applied to Sodankylä Geophysical Observatory ionograms

Cited by 23 publications

References 16 publications

Multi‐Instrumental Observations of Nonunderdense Meteor Trails

Multi‐Instrumental Observations of Nonunderdense Meteor Trails

Ionosonde total electron content evaluation using International Global Navigation Satellite System Service data

Ground Echoes Observed by the Meteor Radar and High‐Speed Auroral Observations in the Substorm Growth Phase

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