Validation of various ionospheric models in the high-latitudinal zone

Maltseva, O. A.; Nikitenko, Tatyana

doi:10.1016/j.asr.2020.09.016

Cited by 6 publications

(3 citation statements)

References 15 publications

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“…These limitations inspired the development of the Empirical Canadian High Arctic Ionospheric Model (E‐CHAIM), which was designed explicitly to better represent the climatological ionosphere at high latitudes (Themens et al., 2017; Themens, Jayachandran, & McCaffrey, 2019; Themens, Jayachandran, & Varney, 2018). The model generally exhibits strong performance in the polar cap, auroral zone, and Russian sector (Maltseva & Nikitenko, 2021; Themens, Jayachandran, McCaffrey, Reid, & Varney, 2019; Themens et al., 2021); however, it struggles at sub‐auroral latitudes in the North American sector (Themens et al., 2021) and, despite doing better than the IRI at high latitudes, it is still only capable of representing up to 50% of the amplitude and 4%–25% of the variance of ionospheric variability on intermediate timescales (Themens et al., 2020). This ultimately necessitates the use of data assimilation to improve further upon E‐CHAIM's representation over North America and to capture smaller spatial and temporal scales.…”

Section: Introductionmentioning

confidence: 99%

A‐CHAIM: Near‐Real‐Time Data Assimilation of the High Latitude Ionosphere With a Particle Filter

et al. 2023

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The high latitude ionosphere has historically been a challenging system to model (Buchert, 2020;Lockwood et al., 1990;Rasmussen et al., 1986). A rich collection of external drivers and interactions drive ionospheric behavior, including strong electric fields, magnetospheric coupling via particle precipitation and current systems, and rapid changes in the thermospheric state. These dynamic conditions, paired with a lack of high latitude observations when compared to mid and low latitudes, present a substantial problem for operational ionospheric modeling. With increased interest in polar ionospheric monitoring (Thayaparan et al., 2018) and High Frequency (HF) communications, it is now imperative that a near-real-time, operational model of high latitude electron density be developed and deployed for use in this region.

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Section: Introductionmentioning

confidence: 99%

A‐CHAIM: Near‐Real‐Time Data Assimilation of the High Latitude Ionosphere With a Particle Filter

et al. 2023

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“…These limitations inspired the development of the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM), which was designed explicitly to better represent the climatological ionosphere at high latitudes (Themens et al, 2017;Themens, Jayachandran, & Varney, 2018;Themens, Jayachandran, & McCaffrey, 2019) . The model generally exhibits strong performance in the polar cap, auroral zone, and Russian sector (Themens, Jayachandran, McCaffrey, Reid, & Varney, 2019;Themens et al, 2021;Maltseva & Nikitenko, 2021); however, it struggles at sub-auroral latitudes in the North American sector (Themens et al, 2021) and, despite doing better than the IRI at high latitudes, it is still only capable of representing up to 50% of the amplitude and 4% to 25% of the variance of ionospheric variability on intermediate timescales (Themens et al, 2020). This ultimately necessitates the use of data assimilation to improve further upon E-CHAIM's representation over North America and to capture smaller spatial and temporal scales.…”

Section: Introductionmentioning

confidence: 99%

A-CHAIM: Near-Real-Time Data Assimilation of the High Latitude Ionosphere with a Particle Filter

Reid

Themens

McCaffrey

et al. 2022

Preprint

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The Assimilative Canadian High Arctic Ionospheric Model (A-CHAIM) is an operational ionospheric data assimilation model that provides a 3D representation of the high latitude ionosphere in Near-Real-Time (NRT). A-CHAIM uses low-latency observations slant Total Electron Content (sTEC) from ground-based Global Navigation Satellite System (GNSS) receivers, ionosondes, and vertical TEC from the JASON-3 altimeter satellite to produce an updated electron density model above $45ˆo$ geomagnetic latitude. A-CHAIM is the first operational use of a particle filter data assimilation for space environment modeling, to account for the nonlinear nature of sTEC observations. The large number (>10ˆ4) of simultaneous observations creates significant problems with particle weight degeneracy, which is addressed by combining measurements to form new composite observables. The performance of A-CHAIM is assessed by comparing the model outputs to unassimilated ionosonde observations, as well as to in-situ electron density observations from the SWARM and DMSP satellites. During moderately disturbed conditions from September 21st, 2021 through September 29th, 2021, A-CHAIM demonstrates a 40% to 50% reduction in error relative to the background model in the F2-layer critical frequency (foF2) at midlatitude and auroral reference stations, and little change at higher latitudes. The height of the F2-layer (hmF2) shows a small 5% to 15% improvement at all latitudes. In the topside, A-CHAIM demonstrates a 15% to 20% reduction in error for the Swarm satellites, and a 23% to 28% reduction in error for the DMSP satellites. The reduction in error is distributed evenly over the assimilation region, including in data-sparse regions.

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“…In recent years, the Empirical Canadian High Artic Ionospheric Model (E‐CHAIM) (Themens et al., 2017, 2018; Themens, Jayachandran, & McCaffrey, 2019) has emerged as the most reliable representation of electron densities at northern high latitudes (>50° geomagnetic latitude; Maltseva & Nikitenko, 2020; Themens et al., 2020; Themens, Jayachandran, McCaffrey, Reid, & Varney, 2019). E‐CHAIM is a significant improvement over other models such as the International Reference Ionosphere (IRI) at high latitudes, providing, for example, improvements of up to 60% in N m F 2 in the polar cap (Themens et al., 2017).…”

Section: Introductionmentioning

confidence: 99%

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

2021

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The precipitation of energetic electrons and ions of magnetospheric and solar origin play a significant role in governing the structure and dynamic behavior of the high latitude ionosphere. Persistent particle precipitation in the auroral region, and to a lesser extent in the polar cap, is a significant source of neutral atmospheric ionization, which results in multi-scale ionosphere density structures that are complex in terms of Abstract The Empirical Canadian High Artic Ionospheric Model (E-CHAIM) provides the fourdimensional ionosphere electron density at northern high latitudes (>50° 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 precipitationenhanced 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-meansquare difference between E-CHAIM and ISR measurements decreased by up to 2.9 × 10 10 ele/m 3 (altitude dependent) after inclusion of the precipitation component at auroral sites, and by 2.6 × 10 9 ele/m 3 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. Plain Language SummaryThe Empirical Canadian High Artic Ionospheric Model (E-CHAIM) is a measurement-based model which provides the electron density of the upper atmosphere (the ionosphere) for a user-specified date, time, and location at northern high latitudes (>50° geomagnetic latitude). The Earth's ionosphere can aid or disrupt the operation of technologies such as global navigation and radio communication systems, and thus ionosphere models are a critical component for reliable operation of these systems. E-CHAIM is currently the most reliable model for high-latitude ionosphere densities, which are particularly dynamic and complex due to the vertical orientation of Earth's high latitude magnetic field. A lack of reliable, widespre...

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Validation of various ionospheric models in the high-latitudinal zone

Cited by 6 publications

References 15 publications

A‐CHAIM: Near‐Real‐Time Data Assimilation of the High Latitude Ionosphere With a Particle Filter

A‐CHAIM: Near‐Real‐Time Data Assimilation of the High Latitude Ionosphere With a Particle Filter

A-CHAIM: Near-Real-Time Data Assimilation of the High Latitude Ionosphere with a Particle Filter

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

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