Regional ionosphere specification by assimilating ionosonde data into the SAMI2 model

• Published in: Advances in space research Vol. 64; no. 7; pp. 1343 - 1357
• Main Authors: Kim, Jeong Heon, Kim, Yong Ha, Ssessanga, Nicholas, Jeong, Se Heon, Moon, Su In, Kwak, Young-Sil, Yun, Jong Yeon
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2019
• Subjects: hmF2; Ionosonde; Ionosphere; NmF2; Nowcast model; SAMI2 model; hmF2; Nowcast model; Ionosonde; SAMI2 model; Ionosphere; NmF2
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/j.asr.2019.06.036

•The SAMI2 code has been edited to assimilate measured hmF2 and NmF2 every 15 min.•Effective winds and electron density scale factors are derived from hmF2 and NmF2.•The assimilated model predicts hmF2s and NmF2s reasonably close to measured values. This paper explains an algorithm of estimating the regional ionosphere at mid-latitude by assimilating ionosonde measured data into a first principle physics-based model (SAMI2-CNU). It has been known that many first principle models underperform due to inadequate input drivers, such as neutral winds and compositions in the background thermosphere. As a pilot study, equivalent meridional winds and electron density scale factors were derived every 15 min using F2 peak heights (hmF2) and densities (NmF2) obtained from Jeju ionosonde (33.43 N°, 126.30 E°), and then were used as inputs to SAMI2-CNU. SAMI2-CNU is an in-house revised version of the 2- dimensional ionosphere model (SAMI2), developed at Naval Research Laboratory (Huba et al., 2000; Kim and Kim, 2016). Results are obtained at a meridional plane of 127° geographic longitude on a geomagnetically quiet day of each season in the year 2014. SAMI2-CNU was found to predict the next 15-min hmF2s and NmF2s reasonably close to measured values at Jeju, Icheon (37.14 N°, 127.54 E°) and Okinawa (26.68 N°, 128.15 E°) (sites near the same meridional plane), showing a superior performance, compared to the original SAMI2 and the International Reference Ionosphere (IRI) 2016 model. Thus, this study demonstrates that a physic model, SAMI2-CNU, can be used as a nowcast model of the regional mid-latitude ionosphere by assimilating ionosonde data in near-real time.