The Limits of Empirical Electron Density Modeling: Examining the Capacity of E‐CHAIM and the IRI for Modeling Intermediate (1‐ to 30‐Day) Timescales at High Latitudes

Radio Science ◽  
2020 ◽  
Vol 55 (4) ◽  
Author(s):  
David R. Themens ◽  
P. T. Jayachandran ◽  
Benjamin Reid ◽  
Anthony M. McCaffrey
Keyword(s):  
Electron Density ◽  
High Latitudes ◽  
Density Modeling

scholarly journals EISCAT verification in the development of ionospheric tomography

1996 ◽  
Vol 14 (12) ◽  
pp. 1413-1421 ◽  
Author(s):  
I. K. Walker ◽  
J. A. T. Heaton ◽  
L. Kersley ◽  
C. N. Mitchell ◽  
S. E. Pryse ◽  
...  
Keyword(s):  
Electron Density ◽  
Tomographic Reconstruction ◽  
Tomographic Image ◽  
High Latitudes ◽  
Ionospheric Electron Density ◽  
Ionospheric Tomography ◽  
Eiscat Radar

Abstract. This paper highlights the important role played by the EISCAT radar for verification in the development of tomographic techniques to produce images of ionospheric electron density. A brief review is given of some of the stages in the application of tomographic reconstruction techniques to the ionosphere. Results are presented to illustrate the effectiveness of the method in imaging ionospheric structures at high latitudes. In addition, the results include the first tomographic image of the ionosphere for a region extending from mid-latitudes over mainland Scandinavia to high latitudes above Svalbard.

Studying the Ionospheric Responses Induced by a Geomagnetic Storm in September 2017 with Multiple Observations in America

2020 ◽  
Author(s):  
Yang Liu ◽  
Zheng Li ◽  
Jinling Wang
Keyword(s):  
Electron Density ◽  
Geomagnetic Storm ◽  
Geomagnetic Storms ◽  
Ionospheric Irregularities ◽  
Electron Content ◽  
High Latitudes ◽  
Total Electron ◽  
Multiple Observations ◽  
The Usa ◽  
Plasma Depletions

<p>A series of studies have suggested that a geomagnetic storm can accelerate the formation of plasma depletions and the generation of ionospheric irregularities. Using observation data from the Continuously Operating Reference Stations (CORS) network in the USA, the responses of the ionospheric total electron content (TEC) to the geomagnetic storm on September 8, 2017 are studied in detail. A mid-latitude trough was discovered from 01:00 UT to 06:00 UT in the USA with a length exceeding 5000 km. The probable causes are the combination of a classic negative storm response with increments in the neutral composition and the expansion of the auroral oval, pushing the mid-latitude trough equatorward.  Super-scale plasma depletion was observed by SWARM data accompanied by the expansion of mid-latitude trough. Both PPEF from high latitudes and pole-ward neutral wind are responsible for the large-scale ionospheric irregularities. Medium-scale travelling ionospheric disturbances (MSTID) with wavelengths of 600–700 km were generated accompanied by a drop and perturbation in the electron density. The intensity of the MSTID fluctuations reached over 2.5 TECU, which were discovered by filtering the differential TEC. The evolution of plasma depletions were associated with the MSTID propagating from high latitudes to low latitudes. SWARM spaceborne observations also showed a drop in the electron density from 10<sup>5</sup> to 10<sup>3</sup> compared to the background values at 28° N, 96° W, and 25° N, 95° W. This research investigates super-scale plasma depletions generated by geomagnetic storms using both CORS GNSS and spaceborne observations. The proposed work is valuable for better understanding the evolution of ionospheric depletions during geomagnetic storms.</p>

Evaluation of E-Layer Dominated Ionosphere Events Using CHAMP, COSMIC/FORMOSAT-3 and FY3C Data

2020 ◽  
Author(s):  
Sumon Kamal ◽  
Norbert Jakowski ◽  
Mohammed M. Hoque ◽  
Jens Wickert
Keyword(s):  
Electron Density ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Weather Conditions ◽  
Polar Regions ◽  
High Latitudes ◽  
Density Profiles ◽  
Temporal Occurrence ◽  
Electron Density Profiles ◽  
Activity Dependent

<p>Under certain space weather conditions the ionization level of the ionospheric E layer can dominate over that of the F2 layer. This phenomenon is known as “E layer dominated ionosphere” (ELDI) and occurs primarily at high latitudes in the polar regions. The corresponding electron density profiles show their peak ionization at the E layer height between 80 km and 150 km above the Earth’s surface. In this work we have evaluated the influence of space weather and geophysical conditions on the occurrence of ELDI events at high latitudes in the northern and southern hemispheres. For this, we used electron density profiles derived from ionospheric radio occultation measurements aboard CHAMP, COSMIC and FY3C satellites. The used CHAMP data covers the years from 2001 to 2008, the COSMIC data the years from 2006 to 2018 and the FY3C data the years from 2014 to 2018. This provides us continuous data coverage for a long period from 2001 to 2018, containing about 4 million electron density profiles. In addition to the geospatial distribution, we have also investigated the temporal occurrence of ELDI events in the form of the diurnal, the seasonal and the solar activity dependent variation. We have further investigated the influence of geomagnetic storms on the spatial and temporal occurrence of ELDI events.</p>

NeQuick2 and IRI2012 models applied to mid and high latitudes, and the Antarctic ionosphere

2017 ◽  
Vol 29 (3) ◽  
pp. 265-276 ◽  
Author(s):  
M. Pietrella ◽  
B. Nava ◽  
M. Pezzopane ◽  
Y. Migoya Orue ◽  
A. Ippolito ◽  
...  
Keyword(s):  
Electron Density ◽  
Activity Index ◽  
High Latitudes ◽  
Limited Sample ◽  
Density Profiles ◽  
Solar Activity Index ◽  
Macquarie Island ◽  
Electron Density Profiles ◽  
The Antarctic ◽  
Better Than

AbstractWithin the framework of the AUSPICIO (AUtomatic Scaling of Polar Ionograms and Co-operative Ionospheric Observations) project, a limited sample of ionograms recorded mostly in 2001 and 2009, and to a lesser extent in 2006–07 and 2012–15, at the ionospheric observatories of Hobart and Macquarie Island (mid-latitude), Comandante Ferraz and Livingstone Island (high latitude), and Casey, Mawson, Davis and Scott Base (inside the Antarctic Polar Circle (APC)) were considered to study the capability of the NeQuick2 and IRI2012 models for predicting the behaviour of the ionosphere at mid- and high latitudes and over the Antarctic area. The applicability of NeQuick2 and IRI2012 was evaluated as i) climatological models taking as input the F10.7 solar activity index and ii) assimilative models ingesting the foF2 and hmF2 measurements obtained from the electron density profiles provided by the Adaptive Ionospheric Profiler (AIP). The statistical analysis results reveal that the best description of the ionosphere’s electron density is achieved when the AIP measurements are ingested into the NeQuick2 and IRI2012 models. Moreover, NeQuick2 performance is far better than IRI2012 performance outside the APC. Conversely, the IRI2012 model performs better than the NeQuick2 model inside the APC.

Electron Density Modeling of a Streamer Using LASCO Data of 2004 January and February

2006 ◽  
Vol 642 (1) ◽  
pp. 523-532 ◽  
Author(s):  
A. F. Thernisien ◽  
R. A. Howard
Keyword(s):  
Electron Density ◽  
Density Modeling

A new algorithm for improved ionospheric electron density modeling

1995 ◽  
Vol 22 (11) ◽  
pp. 1385-1388 ◽  
Author(s):  
P. G. Richards ◽  
D. G. Torr ◽  
M. E. Hagan ◽  
M. J. Buonsanto
Keyword(s):  
Electron Density ◽  
Ionospheric Electron Density ◽  
Density Modeling

Global Multi-layer Electron Density Modeling Based on Constraint optimization

2020 ◽  
Author(s):  
Ganesh Lalgudi Gopalakrishnan ◽  
Michael Schmidt ◽  
Eren Erdogan
Keyword(s):  
Electron Density ◽  
Space Weather ◽  
Peak Height ◽  
Optimization Approach ◽  
Iri Model ◽  
B Splines ◽  
Weather Events ◽  
The Impact ◽  
Layer Peak ◽  
Density Modeling

<p><span>Electron density is the most important key parameter to describe the </span><span>state of the ionospheric plasma </span><span>varying with latitude, longitude, altitude and time. The upper atmosphere is decomposed into the four layers D, E, F1 and F2 of the ionosphere as well as the plasmasphere. Space weather events manifest themselves with specific "signatures" in distinct ionospheric layers. Therefore, the role of each layer in characterizing the ionosphere during nominal and extreme space weather events is highly important for scientific and operational purposes. </span></p><p><span>Accordingly, we model the total electron density as the sum of the electron densities of the individual layers. The key parameters of each layer, namely peak electron density, the corresponding peak height and scale height, are modeled by series expansions in terms of polynomial B-splines for latitude and trigonometric B-splines for longitude. The Chapman profile function is chosen to define the electron density along the altitude. This way, the electron density modeling is setup as a parameter estimation problem. In the case of modelling multiple layers simultaneously, the estimation of coefficients of the key parameters becomes challenging due to the correlations between the different key parameters. </span></p><p><span>One possibility to address the above issue is by imposing constraints on the ionospheric key parameters (and by extension on the B-spline coefficients). As an example, we constrain the F2 layer peak height to be always above the F1 layer peak height. We also constrain the key parameters to be non-negative and possibly to to certain well defined bounds. This way the physical properties of the ionosphere layers are included in the modelling. We estimate the coefficients with regard to the imposition of the bounds in form of inequality constraints using a convex optimization approach. We describe the underlying mathematical procedure and validate it using </span><span>the IRI model as well as GNSS observations and electron density measurements from occultation missions. For the specific case of using IRI model data as the reference “truth”, we show the performance of the optimization algorithm using a “closed loop” validation. Such a validation allows an in-depth analysis of the impact of choosing a desired number of unknown coefficients to be estimated and the total number of constraints applied. We describe the parameterization of the different ionosphere key parameters considering the specific requirements from operational aspects (such as the need for modelling F2 layer), scientific aspects with regard to ionosphere-thermosphere studies (need for modelling the D, E or F1 layers) and also considering the aspects related to computation load. </span></p><p><span>We describe the advantages of using the optimization approach compared to the unconstrained least squares solution. While such constraints on key parameters can be fixed under nominal ionospheric conditions, but under adverse space weather effects these constraints need to be modified (constraints become stricter or more relaxed). For this purpose, we show the dynamic effect of modifying the constraints on global modelling performance and accuracy. We also provide the uncertainty of the estimated coefficients using a Monte-Carlo approach.</span></p>

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