Bibliography

Development and Validation of Precipitation Enhanced Densities for the Empirical Canadian High Arctic Ionospheric Model

The Empirical Canadian High Artic Ionospheric Model (E-CHAIM) provides the four-dimensional ionosphere electron density at northern high latitudes (\textgreater50° geomagnetic latitude). Despite its emergence as the most reliable model for high-latitude ionosphere density, there remain significant deficiencies in E-CHAIM s representation of the lower ionosphere (below ∼200 km) due to a sparsity of reliable measurements at these altitudes, particularly during energetic particle precipitation events. To address this deficiency, we have developed a precipitation component for E-CHAIM to be driven by satellite-based far-ultraviolet (FUV) imager data. Satellite observations of FUV emissions may be used to infer the characteristics of energetic particle precipitation and subsequently calculate the precipitation-enhanced ionization rates and ionosphere densities. In order to demonstrate the improvement of E-CHAIM s ionosphere density representation with the addition of a precipitation component, this paper presents comparisons of E-CHAIM precipitation-enhanced densities with ionosphere density measurements of three auroral region incoherent scatter radars (ISRs) and one polar cap ISR. Calculations for 29,038 satellite imager and ISR conjunctions during the years 2005–2019 revealed that the root-mean-square difference between E-CHAIM and ISR measurements decreased by up to 2.9 × 1010 ele/m3 (altitude dependent) after inclusion of the precipitation component at auroral sites, and by 2.6 × 109 ele/m3 in the polar cap. Improvements were most substantial in the winter season and during active auroral conditions. The sensitivity of precipitation-enhanced densities to uncertainties inherent to the calculation method was also examined, with the bulk of the errors due to uncertainties in FUV imager data and choice of distribution function for precipitation energy spectra.

Watson, C.; Themens, D.; Jayachandran, P.;

Published by: Space Weather      Published on:

YEAR: 2021     DOI: 10.1029/2021SW002779

auroral region; Ionosphere; ionosphere density; magnetosphere-ionosphere-thermosphere coupling; particle precipitation; polar cap

A precipitation parameterization for the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) and other empirical models

Precipitation flux and mean energy are then modeled based on TIMED GUVI-and DMSP SSUSI-inferred precipitation characteristics. Beginning with an overview of how the

Themens, David; Jayachandran, Thayyil; McCaffrey, Anthony; Reid, Benjamin; Watson, Chris;

Published by: 43rd COSPAR Scientific Assembly. Held 28 January-4 February      Published on:

YEAR: 2021     DOI:

Development of a GUVI/SSUSI-based model for E-region electron density enhancements at northern auroral latitudes

Watson, Christopher; Themens, David; Jayachandran, PT;

Published by:       Published on:

YEAR: 2019     DOI:

An interhemispheric comparison of GPS phase scintillation with auroral emission observed at the South Pole and from the DMSP satellite

The global positioning system (GPS) phase scintillation caused by highlatitude ionospheric irregularities during an intense high-speed stream (HSS) of the solar wind from April 29 to May 5, 2011, was observed using arrays of GPS ionospheric scintillation and total electron content monitors in the Arctic and Antarctica. The one-minute phase-scintillation index derived from the data sampled at 50 Hz was complemented by a proxy index (delta phase rate) obtained from 1-Hz GPS data. The scintillation occurrence coincided with the aurora borealis and aurora australis observed by an all-sky imager at the South Pole, and by special sensor ultraviolet scanning imagers on board satellites of the Defense Meteorological Satellites Program. The South Pole (SP) station is approximately conjugate with two Canadian High Arctic Ionospheric Network stations on Baffin Island, Canada, which provided the opportunity to study magnetic conjugacy of scintillation with support of riometers and magnetometers. The GPS ionospheric pierce points were mapped at their actual or conjugate locations, along with the auroral emission over the South Pole, assuming an altitude of 120 km. As the aurora brightened and/or drifted across the field of view of the all-sky imager, sequences of scintillation events were observed that indicated conjugate auroras as a locator of simultaneous or delayed bipolar scintillation events. In spite of the greater scintillation intensity in the auroral oval, where phase scintillation sometimes exceeded 1 radian during the auroral break-up and substorms, the percentage occurrence of moderate scintillation was highest in the cusp. Interhemispheric comparisons of bipolar scintillation maps show that the scintillation occurrence is significantly higher in the southern cusp and polar cap.

Prikryl, Paul; Zhang, Yongliang; Ebihara, Yusuke; Ghoddousi-Fard, Reza; Jayachandran, Periyadan; Kinrade, Joe; Mitchell, Cathryn; Weatherwax, Allan; Bust, Gary; Cilliers, Pierre; , others;

Published by: Annals of Geophysics      Published on:

YEAR: 2013     DOI:

An interhemispheric comparison of GPS phase scintillation with auroral emission observed at South Pole and from DMSP satellite

Prikryl, Paul; Zhang, Yongliang; Ebihara, Yusuke; Ghoddousi-Fard, Reza; Jayachandran, Periyadan; Kinrade, Joe; Mitchell, Cathryn; Weatherwax, Allan; Bust, Gary; Cilliers, Pierre; , others;

Published by: Annals of Geophysics      Published on:

YEAR: 2013     DOI:

Day-to-day variability of equatorial anomaly in GPS-TEC during low solar activity period

Aggarwal, Malini; Joshi, H.P.; Iyer, K.N.; Kwak, Y.-S.; Lee, J.J.; Chandra, H.; Cho, K.S.;

Published by: Advances in Space Research      Published on: Jan-06-2012

YEAR: 2012     DOI: 10.1016/j.asr.2012.03.005

Oscillations of the equatorward boundary of the ion auroral oval – radar observations

Three SuperDARN radars in the afternoon-midnight sector of the auroral oval detected a boundary oscillation, originating near ∼1800 MLT sector. Analysis of the phase of the oscillations measured in three meridians indicates that the disturbance has a longitudinally (azimuthally) isolated source and away from which it propagates. The eastward and westward phase speeds are 2.6 and 3.6 km/s respectively and the period is roughly 28 minutes. An examination of the geo-synchronous magnetic field inclination also revealed oscillations similar to the oscillations of the boundary. Solar wind and IMF conditions were steady during the period except for variations of the IMF By component. The IMF By component showed variations similar to the oscillations in the boundary and the geo-synchronous magnetic field inclination. During reduced and negative IMF By, the boundary was moving equatorward, while during increased or positive IMF By it was moving poleward. The variations in the magnetic field inclination measured at geosynchronous orbit by the GOES satellites were consistent with these boundary motions: decreases (more stretched) and increases (more dipolar) in the inclination corresponded to equatorward and poleward moving boundaries, respectively. Polar cap convection also showed changes in the direction of the convection in response to the change in the IMF By component. Observed oscillation of the boundary can be explained by stretching of the tail field lines due to asymmetric merging associated with changes in the By component of the interplanetary magnetic field.

Jayachandran, P.; Sato, N.; Ebihara, Y.; Yukimatu, A.; Kadokura, A.; MacDougall, J.; Donovan, E.; Liou, K.;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2008     DOI: https://doi.org/10.1029/2007JA012870

Boundary oscillation; SuperDARN radars; Convection