The pulkovo astrolabe catalogue (PAC)

Gubanov, V. S.; Brumberg, E. V.; Godisov, N. P.; Vasiljev, V. M.; Solina, N. I.; Yagudin, L. I.

doi:10.1080/10556799208205343

Cited by 3 publications

(2 citation statements)

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“…These are the inputs to the ion chemistry and energetics part of the model, in which the time-dependent coupled continuity equations for all important positive ions and minor neutral species are solved along with the electron and ion energy equations (Lanchester et al, 2001). Initial conditions relevant to each event include estimates of neutral densities from the Mass Spectrometer Incoherent Scatter (MSIS) model (Hedin, 1991) and solar and geomagnetic indices, such as the F 10.7 solar radio flux and the A p index. The cross sections used are those described in Ashrafi et al (2009) for the ASK1 (N 2 ) emission and Julienne and Davis (1976) for the ASK3 (O) emission.…”

Section: Energy and Energy Fluxmentioning

confidence: 99%

Horizontal electric fields from flow of auroral O+(2P) ions at sub-second temporal resolution

et al. 2020

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Abstract. Electric fields are a ubiquitous feature of the ionosphere and are intimately linked with aurora through particle precipitation and field-aligned currents. They exhibit order-of-magnitude changes on temporal and spatial scales of seconds and kilometres respectively which are not easy to measure; knowing their true magnitude and temporal variability is important for a theoretical understanding of auroral processes. We present a unique method to estimate ionospheric electric fields in the region close to (kilometre scale) a dynamic auroral arc by solving the continuity equation for the metastable O+(2P) ions, which emit as they move under the influence of electric fields during their 5 s lifetime. The main advantage of this optical method is the increase in temporal resolution over other methods such as ground-based radars. Simultaneous measurements of emission at 732.0 nm (from the O+(2P) ions) and prompt emissions at 673.0 nm (N2) and 777.4 nm (O), all at high spatial (100 m) and temporal (0.05 s) resolution, are used in the solution of the continuity equation, which gives the dynamic changes of the O+ ion population at all heights in a 3D volume close to the magnetic zenith. Perspective effects are taken into account by a new geometric method, which is based on an accurate estimate of the magnetic zenith position. The emissions resulting from the metastable ions are converted to brightness images by projecting them onto the plane of the ground, and the projected images are then compared with the measured images. The flow velocity of the ions is a free parameter in the solution of the continuity equation; the value that minimises the difference between the modelled and observed images is the extracted flow velocity at each time step. We demonstrate the method with an example event during the passage of a brightening arc feature, lasting about 10 s, in which the inferred electric fields vary between 20 and 120 mV m−1. These inferred electric fields are compared with SuperDARN measurements, which have an average value of 30 mV m−1. An excellent agreement is found in the magnitude and direction of the background electric field; an increase in magnitude during the brightening of the arc feature supports theories of small-scale auroral arc formation and electrodynamics.

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Section: Energy and Energy Fluxmentioning

confidence: 99%

Horizontal electric fields from flow of auroral O+(2P) ions at sub-second temporal resolution

et al. 2020

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“…All data are dark and flat-field corrected, background subtracted and intensity calibrated using star fluxes. Measured intensities of tens of stars per image are compared with spectral irradiances in absolute units from tabulated values (Gubanov et al, 1992;Cox, 2000;Grubbs II et al).…”

Section: Introductionmentioning

confidence: 99%

Horizontal electric fields from flow of auroral O+(2P) ions at sub-second resolution

Tuttle¹,

Lanchester²,

Gustavsson³

et al. 2020

Preprint

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Abstract. Electric fields are a ubiquitous feature of the ionosphere and are intimately linked with aurora through particle precipitation and field-aligned currents. We present a unique method to estimate ionospheric electric fields beside a dynamic auroral feature by solving the continuity equation for the metastable O+(2P) ions, which emit as they move under the influence of electric fields during their 5 s lifetime. Simultaneous measurements of emission at 732.0 nm (from the O+(2P) ions), and prompt emissions at 673.0 nm (N2) and 777.4 nm (O), all at high spatial (100 m) and temporal (0.05 s) resolution, are used in the solution of the continuity equation, which gives the dynamic changes of the O+ ion population at all heights in a 3D volume close to the magnetic zenith. Perspective effects are taken into account by a new geometric method, which is based on an accurate estimate of the magnetic zenith position. The emissions resulting from the metastable ions are converted to brightness images by projecting onto the plane of the ground, which are compared with the measured images. The flow velocity of the ions is a free parameter in the solution of the continuity equation; the value that minimizes the difference between the modelled and observed images is the extracted flow velocity at each time step. We demonstrate the method with an example event during the passage of a brightening arc feature, lasting about 10 s, in which the inferred electric fields vary between 20 and 120 mV m−1. These inferred electric fields are compared with SuperDARN measurements, which have an average value of 30 mV m−1. An excellent agreement is found in magnitude and direction of the background electric field; an increase in magnitude during the brightening of the arc feature supports theories of small scale auroral arc formation and electrodynamics.

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Parametric adjustment of astrometric data

Gubanov

1993

Astronomical & Astrophysical Transactions

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The pulkovo astrolabe catalogue (PAC)

Cited by 3 publications

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Horizontal electric fields from flow of auroral O<sup>+</sup>(<sup>2</sup>P) ions at sub-second temporal resolution

Horizontal electric fields from flow of auroral O<sup>+</sup>(<sup>2</sup>P) ions at sub-second temporal resolution

Horizontal electric fields from flow of auroral O<sup>+</sup>(<sup>2</sup>P) ions at sub-second resolution

Parametric adjustment of astrometric data

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The pulkovo astrolabe catalogue (PAC)

Cited by 3 publications

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Horizontal electric fields from flow of auroral O&lt;sup&gt;+&lt;/sup&gt;(&lt;sup&gt;2&lt;/sup&gt;P) ions at sub-second temporal resolution

Horizontal electric fields from flow of auroral O&lt;sup&gt;+&lt;/sup&gt;(&lt;sup&gt;2&lt;/sup&gt;P) ions at sub-second temporal resolution

Horizontal electric fields from flow of auroral O&lt;sup&gt;+&lt;/sup&gt;(&lt;sup&gt;2&lt;/sup&gt;P) ions at sub-second resolution

Parametric adjustment of astrometric data

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Horizontal electric fields from flow of auroral O<sup>+</sup>(<sup>2</sup>P) ions at sub-second temporal resolution

Horizontal electric fields from flow of auroral O<sup>+</sup>(<sup>2</sup>P) ions at sub-second temporal resolution

Horizontal electric fields from flow of auroral O<sup>+</sup>(<sup>2</sup>P) ions at sub-second resolution