Gaussian Markov Random Field Priors in Ionospheric 3-D Multi-Instrument Tomography

Norberg, Johannes; Vierinen, Juha; Roininen, Lassi; Orispää, Mikko; Kauristie, Kirsti; Rideout, W.; Coster, A. J.; Lehtinen, Markku

doi:10.1109/tgrs.2018.2847026

Cited by 32 publications

(37 citation statements)

References 31 publications

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“…Figures a and b both show excess of electrons within the locations where the dunes were observed with digital cameras. Despite the zonal variation present in Figure , the zonal difference in the electron density is not significant within the tomographic accuracy (Norberg et al, ), suggesting that the resolution is not good enough to discern any longitudinal structures in the 45 km scale. To conclude whether there is a variation within the precipitation source, one needs spacecraft measurements above the dunes, which are not available during this event.…”

Section: Dune Characteristicsmentioning

confidence: 90%

“…The oscillation within the auroral emission is either due to the variation in the precipitating electron source or by undulations of the underlying atmospheric Oxygen density. To investigate this, Figure a presents ionospheric vertical total electron content (vTEC) at 17:37–17:41 UT at pierce points, at which the Global Positioning Satellite (GPS) radio signals intersect with a thin layer ionospheric model assumed to be at 250 km altitude, while Figure b presents ionospheric vTEC integrated from a three‐dimensional GPS satellite tomography electron density reconstruction (Norberg et al, ). Essentially, Figure a is more directly based on actual measurements, but makes a more drastic assumption on the ionosphere and its height, which are more elaborately handled in Figure b.…”

Section: Dune Characteristicsmentioning

confidence: 99%

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Citizen Scientists Discover a New Auroral Form: Dunes Provide Insight Into the Upper Atmosphere

Palmroth

Grandin

Helin³

et al. 2020

AGU Advances

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Auroral forms are like fingerprints linking optical features to physical phenomena in the near-Earth space. While discovering new forms is rare, recently, scientists reported of citizens' observations of STEVE, a pinkish optical manifestation of subauroral ionospheric drifts that were not thought to be visible to the naked eye. Here, we present a new auroral form named "the dunes". On 7 October 2018, citizen observers took multiple digital photographs of the same dunes simultaneously from different locations in Finland and Sweden. We develop a triangulation method to analyze the photographs and conclude that the dunes are a monochromatic wave field with a wavelength of about 45 km within a thin layer at 100 km altitude. Supporting data suggest that the dunes manifest atmospheric waves, possibly mesospheric bores, which are rarely detected, and have not previously been observed via diffuse aurora nor at auroral latitudes and altitudes. The dunes present a new opportunity to investigate the coupling of the lower/middle atmosphere to the thermosphere and ionosphere. Our paper adds to the growing body of work that illustrates the value of citizen scientist images in carrying out quantitative analysis of optical phenomena, especially at small scales at subauroral latitudes. Further, the dune project presents means to create general interest toward physics, emphasizing that citizens can take part in scientific work by helping to uncover new phenomena. Plain Language SummaryAbove Earth's atmosphere at about 80-120 km altitude, lies a region that is often dubbed as the "ignorosphere," one of the least explored regions at our planet. We present a new auroral form spotted by citizen scientists and show how it can be used to investigate the ignorosphere. We name the new form as "the dunes" and develop a method to analyze the citizen scientist pictures using the stars on the skies as reference points. The new method and other supporting data indicate that the dunes are a monochromatic wave field with a wavelength of about 45 km within a thin layer at 100 km altitude, right in the ignorosphere, where atmosphere meets the electromagnetic forcing from space. The analysis suggests that the dunes manifest atmospheric waves, possibly a rare phenomenon called mesospheric bores, which are large wave fields propagating in the ignorosphere. They have not previously been observed via aurora, nor at auroral latitudes and altitudes. The dunes present a new opportunity to investigate the ignorosphere and its driving from above. Further, the dune project presents means to create general interest toward physics, emphasizing that citizens can take part in scientific work by helping to uncover new phenomena. Key Points: • Citizen scientists discover a new auroral form, named the dunes, presenting a large-scale monochromatic wave field • We develop a triangulation method using citizen scientist photographs as science data • We suggest that the dunes manifest mesospheric bores, which have not previously been observed in the diffuse aurora Suppo...

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Section: Dune Characteristicsmentioning

confidence: 90%

Section: Dune Characteristicsmentioning

confidence: 99%

Citizen Scientists Discover a New Auroral Form: Dunes Provide Insight Into the Upper Atmosphere

Palmroth

Grandin

Helin³

et al. 2020

AGU Advances

View full text Add to dashboard Cite

show abstract

“…The oscillation within the auroral emission is either due to the variation in the precipitating electron source or by undulations of the underlying atmospheric Oxygen density. To investigate this, Figure 5a presents ionospheric vertical total electron content (vTEC) at 17:37-17:41 UT at pierce points, at which the Global Positioning Satellite (GPS) radio signals intersect with a thin layer ionospheric model assumed to be at 250 km altitude, while Figure 5b presents ionospheric vTEC integrated from a three-dimensional GPS satellite tomography electron density reconstruction (Norberg et al, 2018). Essentially, Figure 5a is more directly based on actual measurements, but makes a more drastic assumption on the ionosphere and its height, which are more elaborately handled in Figure 5b.…”

Section: Dune Characteristicsmentioning

confidence: 99%

Citizen scientists discover a new auroral form: Dunes provide insight into the upper atmosphere

Palmroth

Grandin

Helin³

et al. 2020

Preprint

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<p>Auroral forms are like fingerprints linking optical features to physical phenomena in the near-Earth space. While discovering new forms is rare, recently scientists reported of citizens' observations of STEVE, a pinkish optical manifestation of subauroral ionospheric drifts that were not thought to be visible to the naked eye. Here, we present a new auroral form named "the dunes". On Oct 7, 2018, citizen observers took multiple digital photographs of the same dunes simultaneously from different locations in Finland and Sweden. We develop a triangulation method to analyse the photographs, and conclude that the dunes are a monochromatic wave field with a wavelength of about 45 km within a thin layer at 100 km altitude. Supporting data suggest that the dunes manifest atmospheric waves, possibly mesospheric bores, which are rarely detected, and have not previously been observed via diffuse aurora, nor at auroral latitudes and altitudes. The dunes present a new opportunity to investigate the coupling of the lower/middle atmosphere to the thermosphere and ionosphere. We conclude that the the dunes may provide new insights into the structure of the mesopause as a response to driving by ionospheric energy deposition via Joule heating and electron precipitation.&#160;Further, our paper adds to the growing body of work that illustrates the value of citizen scientist images in carrying out quantitative analysis of optical phenomena, especially at small scales at subauroral latitudes. The dune project presents means to create general interest towards physics, emphasising that citizens can take part in scientific work by helping to uncover new phenomena.</p>

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“…The construction of more ground-based GNSS networks and the application of more space-based GNSS observations make it possible to reconstruct the three-dimensional IED distributions. Therefore, the GNSS-based ionospheric tomography technique has attracted the interest of many scholars [7][8][9][10][11][12][13][14][15][16]. Theoretical and experimental research has been conducted, and some meaningful results have been achieved.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Smoothness Constraint Ionospheric Tomography Algorithm

Wen

Mei

2020

Sensors

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Ionospheric tomography reconstruction based on global navigation satellite system observations is usually an ill-posed problem. To resolve it, an adaptive smoothness constraint ionospheric tomography algorithm is proposed in this work. The new algorithm performs an adaptive adjustment for the constrained weight coefficients of the tomography system. The computational efficiency and the reconstructed quality of ionospheric imaging are improved by using the new algorithm. A numerical simulation experiment was conducted in order to validate the feasibility and superiority of the algorithm. The statistical results of the reconstructed errors and the comparisons of ionospheric profiles confirmed the superiority of the new algorithm. Finally, the new algorithm was successfully applied to reconstruct three-dimensional ionospheric images under geomagnetic quiet and geomagnetic disturbance conditions over Hunan province. The tomographic results are reasonable and consistent with the general behavior of the ionosphere. The positive and negative phase storm effects are found during geomagnetic storm occurrence.

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Gaussian Markov Random Field Priors in Ionospheric 3-D Multi-Instrument Tomography

Cited by 32 publications

References 31 publications

Citizen Scientists Discover a New Auroral Form: Dunes Provide Insight Into the Upper Atmosphere

Citizen Scientists Discover a New Auroral Form: Dunes Provide Insight Into the Upper Atmosphere

Citizen scientists discover a new auroral form: Dunes provide insight into the upper atmosphere

Adaptive Smoothness Constraint Ionospheric Tomography Algorithm

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