Bibliography

Model of the E-Layer Critical Frequency for the Auroral Region

A new foE model for the auroral region is constructed; the model is based on an analysis of the models of auroral electron precipitations, the boundaries of the discrete and diffusive aurora, the main ionospheric trough, and measurements of the E-layer critical frequency foE. The model is an analytical model. It consists of solar (foEsol) and auroral (foEavr) components. The solar component of the model does not depend of geomagnetic activity. It depends on solar activity via the F index, which is determined by the solar radio emission flux at a wavelength of 10.7 cm over the previous day and three solar rotations. The auroral component of the model does not depend of solar activity. It depends on geomagnetic activity via the effective Kp* index, which takes into account the prehistory of changes in this activity. The model indirectly takes into account the dependence of the relative contribution of  foEsol and  foEavr to the total  foE value on the difference in the heights of the maxima of these model components via the addition of a coefficient. The model qualitatively takes into account the effect of the winter anomaly in foEavr via the addition of a function. It is found that the errors of the new foE model in the auroral region at the nighttime hours are much lower than those in the international IRI model (with the STORM-E option) for both moderate and high geomagnetic activity. For example, the comparison with data from ionospheric stations shows that the IRI model underestimates foE in these conditions by approximately a factor of 2 on average. The average shift in foE relative to the experimental data in the new model does not exceed 20\%.

Deminov, M.; Shubin, V.; Badin, V.;

Published by: Geomagnetism and Aeronomy      Published on: sep

YEAR: 2021     DOI: 10.1134/S0016793221050054

Improved model of ionosphere variability and study for long-term statistical characteristics

Ionospheric variability is influenced by many factors, such as solar radiation, neutral atmosphere composition, and geomagnetic disturbances. Mainly characterized by the total electron content (TEC) and electron density, the climatology of the ionosphere features temporal and spatial changes. Establishing a multivariant regression model helps substantially in better understanding the ionosphere characteristics and their long-term variability. In this paper, an improvement of the existing ionosphere multivariate linear fitting regression model is proposed and investigated using data from both the ionosonde and the global ionosphere map (GIM) derived from ground-based Global Navigation Satellite System (GNSS) observations. The proposed method gives more consideration to the impact of the solar activity and adds modeling of the annual periodic fluctuations and half-year periodic fluctuations for the F10.7 index. The improved model is verified to have a better correlation with the real observations and can help reduce the calculation uncertainty. Moreover, the proposed model is used to evaluate the fitting accuracy of the GIMs produced by five authorized data analysis centers from the International GNSS Service (IGS). The results show that there is a fixing hole in the North America region for the GIM model where the correlation between the GIM and the proposed model always returns lower values compared to other places.

Bin, Xueheng; Liu, Yang;

Published by: Chinese Journal of Aeronautics      Published on: feb

YEAR: 2021     DOI: 10.1016/j.cja.2020.03.018

total electron content; Analysis of anomalies; Long-term statistics; Regression model

Evaluating Auroral Forecasts Against Satellite Observations

The aurora is a readily visible phenomenon of interest to many members of the public. However, the aurora and associated phenomena can also significantly impact communications, ground-based infrastructure, and high-altitude radiation exposure. Forecasting the location of the auroral oval is therefore a key component of space weather forecast operations. A version of the OVATION-Prime 2013 auroral precipitation model (Newell et al., 2014, https://doi.org/10.1002/2014sw001056) was used by the UK Met Office Space Weather Operations Centre (MOSWOC). The operational implementation of the OVATION-Prime 2013 model at the UK Met Office delivered a 30-min forecast of the location of the auroral oval and the probability of observing the aurora. Using weather forecast evaluation techniques, we evaluate the ability of the OVATION-Prime 2013 model forecasts to predict the location and probability of the aurora occurring by comparing the forecasts with auroral boundaries determined from data from the IMAGE satellite between 2000 and 2002. Our analysis shows that the operational model performs well at predicting the location of the auroral oval, with a relative operating characteristic (ROC) score of 0.82. The model performance is reduced in the dayside local time sectors (ROC score = 0.59) and during periods of higher geomagnetic activity (ROC score of 0.55 for Kp = 8). As a probabilistic forecast, OVATION-Prime 2013 tends to underpredict the occurrence of aurora by a factor of 1.1–6, while probabilities of over 90\% are overpredicted.

Mooney, M.; Marsh, M.; Forsyth, C.; Sharpe, M.; Hughes, T.; Bingham, S.; Jackson, D.; Rae, I.; Chisham, G.;

Published by: Space Weather      Published on:

YEAR: 2021     DOI: 10.1029/2020SW002688

AURORA; auroral forecasting; forecast verification; OVATION-Prime 2013; ROC scores; space weather

Auroral Energy Flux and Joule Heating Derived From Global Maps of Field-Aligned Currents

We calculate auroral energy flux and Joule heating in the high-latitude ionosphere for 27 geomagnetically active days using two-dimensional maps of field-aligned currents determined by the Active Magnetosphere and Planetary Response Experiment. The energy input to the ionosphere due to Joule heating increases more rapidly with geomagnetic activity than that due to precipitating particles. The energy flux varies more smoothly with time than Joule heating, which is impulsive in nature on time scales from minutes to tens of minutes. These impulsive events correlate well with recoveries in the Sym-H index, with the maximum correlation when compared to Sym-H recoveries 70 min later. Because of prior studies that have associated transient recoveries of Sym-H with substorm expansions, the delay found here suggests that dissipation of energy in the ionosphere occurs during the substorm growth phase prior to the release of magnetic energy caused by diversion of tail currents.

Robinson, R.; Zanetti, L.;

Published by: Geophysical Research Letters      Published on:

YEAR: 2021     DOI: 10.1029/2020GL091527

Geomagnetic storms; Auroral energy flux; auroral energy input; auroral substorms; Joule heating; ring current

Determination of Auroral Electrodynamic Parameters From AMPERE Field-Aligned Current Measurements

We calculate high latitude electrodynamic parameters using global maps of field-aligned currents from the Active Magnetosphere and Planetary Response Experiment (AMPERE). The model is based on previous studies that relate field-aligned currents to auroral Pedersen and Hall conductances measured by incoherent scatter radar. The field-aligned currents and conductances are used to solve for the electric potential at high latitudes from which electric fields are computed. The electric fields are then used with the conductances to calculate horizontal ionospheric currents. We validate the results by simulating the SuperMAG magnetic indices for 30 geomagnetically active days. The correlation coefficients between derived and actual magnetic indices were 0.68, 0.76, and 0.84 for the SMU, SML, and SME indices, respectively. We show examples of times when the simulations differ markedly from the measured indices and attribute them to either small-scale, substorm-related current structures or the effects of neutral winds. Overall, the performance of the model demonstrates that with few exceptions, auroral electrodynamic parameters can be accurately deduced from the global field-aligned current distribution provided by AMPERE.

Robinson, R.; Zanetti, Larry; Anderson, Brian; Vines, Sarah; Gjerloev, Jesper;

Published by: Space Weather      Published on:

YEAR: 2021     DOI: 10.1029/2020SW002677

space weather; auroral currents; auroral electrodynamics; conductivities; electric fields; field-aligned currents

Explicit IMF By-Dependence in Geomagnetic Activity: Quantifying Ionospheric Electrodynamics

Geomagnetic activity is mainly driven by the southward (Bz) component of the interplanetary magnetic field (IMF), which dominates all solar wind coupling functions. Coupling functions also depend on the absolute value of the dawn-dusk (By) component of the IMF, but not on its sign. However, recent studies have shown that for a fixed level of solar wind driving, auroral electrojets in the Northern Hemisphere (NH) are stronger for By \textgreater 0 than for By \textless 0 during NH winter. In NH summer, the dependence on the By sign is reversed. While this By sign dependence, also called the explicit By-dependence, is very strong in the winter hemisphere, it is weak in the summer hemisphere. Moreover, the explicit By-dependence is much stronger in the westward electrojet than in the eastward electrojet. In this study, we study how the explicit IMF By-dependence is coupled with large-scale field-aligned currents (FACs) by using FAC measurements from the Active Magnetosphere and Planetary Electrodynamics Response Experiment and an empirical ionospheric conductance model. We model the complete ionospheric electrodynamics by solving the current continuity equation, and show that during periods of elevated solar wind driving (Bz \textless 0), the IMF By component modulates Regions 1 and 2 FACs in the dawn sector of the winter hemisphere. This leads to an explicit By-dependence in ionospheric conductance and the westward electrojet. We also show that the By-dependence of FACs and conductance is weak in the dusk sector, which explains the earlier observation of the weak By-dependence of the eastward electrojet.

Holappa, L.; Robinson, R.; Pulkkinen, A.; Asikainen, T.; Mursula, K.;

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

YEAR: 2021     DOI: 10.1029/2021JA029202

space weather; magnetosphere-ionosphere coupling; field-aligned currents; geomagnetic activity

Statistical relations between auroral electrical conductances and field-aligned currents at high latitudes

Robinson, RM; Kaeppler, Stephen; Zanetti, Larry; Anderson, Brian; Vines, Sarah; Korth, Haje; Fitzmaurice, Anna;

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

YEAR: 2020     DOI:

Space Weather Modeling Capabilities Assessment: Auroral Precipitation and High-Latitude Ionospheric Electrodynamics

As part of its International Capabilities Assessment effort, the Community Coordinated Modeling Center initiated several working teams, one of which is focused on the validation of models and methods for determining auroral electrodynamic parameters, including particle precipitation, conductivities, electric fields, neutral density and winds, currents, Joule heating, auroral boundaries, and ion outflow. Auroral electrodynamic properties are needed as input to space weather models, to test and validate the accuracy of physical models, and to provide needed information for space weather customers and researchers. The working team developed a process for validating auroral electrodynamic quantities that begins with the selection of a set of events, followed by construction of ground truth databases using all available data and assimilative data analysis techniques. Using optimized, predefined metrics, the ground truth data for selected events can be used to assess model performance and improvement over time. The availability of global observations and sophisticated data assimilation techniques provides the means to create accurate ground truth databases routinely and accurately.

Robinson, Robert; Zhang, Yongliang; Garcia-Sage, Katherine; Fang, Xiaohua; Verkhoglyadova, Olga; Ngwira, Chigomezyo; Bingham, Suzy; Kosar, Burcu; Zheng, Yihua; Kaeppler, Stephen; Liemohn, Michael; Weygand, James; Crowley, Geoffrey; Merkin, Viacheslav; McGranaghan, Ryan; Mannucci, Anthony;

Published by: Space Weather      Published on: 01/2019

YEAR: 2019     DOI: 10.1029/2018SW002127

Space Weather Modeling Capabilities Assessment: Auroral Precipitation and High-Latitude Ionospheric Electrodynamics

As part of its International Capabilities Assessment effort, the Community Coordinated Modeling Center initiated several working teams, one of which is focused on the validation of models and methods for determining auroral electrodynamic parameters, including particle precipitation, conductivities, electric fields, neutral density and winds, currents, Joule heating, auroral boundaries, and ion outflow. Auroral electrodynamic properties are needed as input to space weather models, to test and validate the accuracy of physical models, and to provide needed information for space weather customers and researchers. The working team developed a process for validating auroral electrodynamic quantities that begins with the selection of a set of events, followed by construction of ground truth databases using all available data and assimilative data analysis techniques. Using optimized, predefined metrics, the ground truth data for selected events can be used to assess model performance and improvement over time. The availability of global observations and sophisticated data assimilation techniques provides the means to create accurate ground truth databases routinely and accurately.

Robinson, Robert; Zhang, Yongliang; Garcia-Sage, Katherine; Fang, Xiaohua; Verkhoglyadova, Olga; Ngwira, Chigomezyo; Bingham, Suzy; Kosar, Burcu; Zheng, Yihua; Kaeppler, Stephen; Liemohn, Michael; Weygand, James; Crowley, Geoffrey; Merkin, Viacheslav; McGranaghan, Ryan; Mannucci, Anthony;

Published by: Space Weather      Published on: 01/2019

YEAR: 2019     DOI: 10.1029/2018SW002127

Space weather modeling capabilities assessment: Auroral precipitation and high-latitude ionospheric electrodynamics

Robinson, Robert; Zhang, Yongliang; Garcia-Sage, Katherine; Fang, Xiaohua; Verkhoglyadova, Olga; Ngwira, Chigomezyo; Bingham, Suzy; Kosar, Burcu; Zheng, Yihua; Kaeppler, Stephen; , others;

Published by: Space Weather      Published on:

YEAR: 2019     DOI:

Space weather modeling capabilities assessment: Auroral precipitation and high-latitude ionospheric electrodynamics

Robinson, Robert; Zhang, Yongliang; Garcia-Sage, Katherine; Fang, Xiaohua; Verkhoglyadova, Olga; Ngwira, Chigomezyo; Bingham, Suzy; Kosar, Burcu; Zheng, Yihua; Kaeppler, Stephen; , others;

Published by: Space Weather      Published on:

YEAR: 2019     DOI:

Advances in Auroral Studies I

Zhang, Yongliang; Paxton, Larry; Robinson, Robert; MacDonald, Elizabeth; Mitchell, Elizabeth;

Published by:       Published on:

YEAR: 2019     DOI:

Small structural differences between two ferrocenyl diphenols determine large discrepancies of reactivity and biological effects

Tonolo, Federica; Salmain, Michèle; Scalcon, Valeria; Top, Siden; Pigeon, Pascal; Folda, Alessandra; Caron, Benoit; Mcglinchey, Michael; Toillon, Robert-Alain; Bindoli, Alberto; , others;

Published by: ChemMedChem      Published on:

YEAR: 2019     DOI:

Statistical Relations Between Field-Aligned Currents and Precipitating Electron Energy Flux

Measurements of field-aligned currents from the Active Magnetosphere and Planetary Electrodynamics Response Experiment are combined with measurements of far ultraviolet emissions from the Global Ultraviolet Imager on the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics satellite to examine the correlation between parallel currents and auroral electron energy flux. The energy flux is derived from the far ultraviolet emissions in the N₂ Lyman-Birge-Hopfield bands. We find that energy flux correlates with field-aligned currents in both upward and downward current regions. The correlations vary with magnetic local time with the strongest dependences near magnetic midnight. The data are binned and averaged to construct a model of precipitating particle energy flux as a function of field-aligned current and magnetic local time. With Active Magnetosphere and Planetary Electrodynamics Response Experiment data as input, the model yields accurate estimates of the hemispheric power input from precipitating particles.

Robinson, R.; Zhang, Y.; Anderson, B.; Zanetti, L.; Korth, H.; Fitzmaurice, A.;

Published by: Geophysical Research Letters      Published on: 08/2018

YEAR: 2018     DOI: 10.1029/2018GL078718

Auroral precipitation and descent of thermospheric NO

Kühl, Sven; Espy, Patrick; Hibbins, Robert; Paxton, Larry; Funke, Bernd;

Published by: 41st COSPAR Scientific Assembly      Published on:

YEAR: 2016     DOI:

Community-wide model validation study for systematic assessment of ionosphere models

Shim, Ja; Kuznetsova, Maria; Rastaetter, Lutz; Bilitza, Dieter; Bingham, Suzy; Bust, Gary; Calfas, Roy; Codrescu, Mihail; Coster, Anthea; Crowley, Geoff; , others;

Published by:       Published on:

YEAR: 2015     DOI: