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

Abstract

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.

GNSS Differential Code Bias Determination Using Rao‐Blackwellized Particle Filtering

“…This region is not readily observed by GNSS sTEC due to orbital geometry, and has enhanced densities which are not well captured by E-CHAIM. As such, A-CHAIM tends to strongly underestimate this region, as seen in Reid et al (2023). Any regional overestimation of topside thickness will coincidentally act to correct this error.…”

“…This vTEC can then be converted to an expected sTEC value using the mapping function in Equation 3. The resulting DCB can then be estimated by comparing the observed sTEC to the GIM vTEC as in Equation 5, where w i is a weight for each observation based on the error from the phase-leveling process (Reid et al, 2023). In all comparisons below, this leveling process is performed by considering a full 24 hr of observations, spanning a single daily GIM file.…”

“…10.1029/2023SW003611 data used in the tests were those collected in near-real-time by the online assimilation system (Reid et al, 2023). In total, 662 unique GNSS stations provided data during the test period.…”

3‐D Ionospheric Imaging Over the South American Region With a New TEC‐Based Ionospheric Data Assimilation System (TIDAS‐SA)

“…Furthermore, empirical ionospheric models, such as the International Reference Ionosphere (IRI, Bilitza, 2001; Bilitza et al., 2017) and the NeQuick model (Nava et al., 2008; Radicella, 2009), have also been extensively employed in the development of ionospheric data assimilation systems. Examples include the Ionospheric Data Assimilation Three/Four‐Dimensional (IDA3D/4D) (Bust et al., 2004, 2007), the Global Ionospheric Specification (GIS) (Lin et al., 2015, 2017), the United States/North American TEC (Fuller‐Rowell et al., 2006; Spencer et al., 2004), the Multi‐Instrument Data Analysis System (MIDAS) (Mitchell & Spencer, 2003; Spencer & Mitchell, 2007), as well as various global/regional ionospheric data assimilation systems driven by multiple data sources (e.g., Aa et al., 2018, 2022; Forsythe et al., 2020, 2021; Galkin et al., 2012; Mengist et al., 2019; Reid et al., 2023; Ssessanga et al., 2019; H. Wu et al., 2022; Yue et al., 2012, 2014). The empirical model‐based data assimilation system has the merits of low computational cost and can be used for ionospheric imaging with potential near‐real‐time capabilities, although it could be somewhat limited by the issue of under‐performance in regions with scarce data.…”

Quantification of Representation Error in the Neutral Winds and Ion Drifts Using Data Assimilation

“…Different studies (Bust et al, 2007;Elvidge & Angling, 2019;Mandrake et al, 2005;Matsuo & Araujo-Pradere, 2011;Qiao et al, 2021;Scherliess et al, 2006;Ssessanga et al, 2021;Wu et al, 2015) have estimated the ionospheric density by ingesting GNSS (Global Navigation Satellite Systems) global measurements of TEC (Total Electron Content). Reid et al (2023) introduced the application of particle filter in Assimilative Canadian High Arctic Ionospheric Model (A-CHAIM), which provides high-latitude ionosphere from ingesting slant TEC data from ionosondes and GNSS receivers, and vertical TEC from JASON-3 altimeter. Pignalberi et al (2019) also ingest global TEC measurements to update the background model International Reference Ionosphere (IRI).…”