GOLD Observations of Longitudinal Variations in the Nighttime Equatorial Ionization Anomaly (EIA) Crests' Latitudes

Eastes, R.; Karan, Deepak K.; Martinis, C. R.; Daniell, R. E.; Gan, Quan; Burns, A. G.; McClintock, William E.

doi:10.1029/2022ja031007

Cited by 11 publications

(14 citation statements)

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“…On the other hand, the absence of a clear southern crest during the June solstice in both flux levels of Figure 3 indicates a weaker solar flux effect on the EIA response to the thermospheric wind. Additionally, Figure 1 indicates that the December solstice EIA crest latitude separation is smaller in the region of large magnetic declination, that is, roughly from Eastern Asia to Western South America, consistent with the study of Eastes et al (2023). This is especially true during the evening.…”

Section: Ionospheric Density Climatology At the Iss Heightsupporting

confidence: 84%

Ion Density Climatology Based on FPMU Measurements on Board the International Space Station

Laranja,

Fejer,

Ridenti

et al. 2023

JGR Space Physics

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We performed, for the first time, a season‐dependent geomagnetically quiet‐time climatology of mid‐ and low‐latitude ion densities during low and moderate solar flux conditions using Floating Potential Measurement Unit (FPMU) observations aboard the International Space Station (ISS) from 2008 to 2019. Our daytime observations indicate that the main characteristics of the equatorial ionization anomaly (EIA) at ∼400 km are consistent with those from other in situ and remote sensing probes. The FPMU daytime densities are also generally in good agreement with the corresponding results from the International Reference Ionosphere (IRI). However, the IRI does not reproduce the mid‐solar flux evening low‐latitude measured densities. In this period, the EIA exhibits strong longitude‐dependent crest‐to‐trough ratios and asymmetries due to the pre‐reversal enhancement (PRE) of the zonal electric field and thermospheric neutral winds. Our data also show strong structuring of the daytime and nighttime plasma densities. This includes a bulge, discussed for the first time here, in the EIA southern crest in the South Atlantic sector during the December solstice and equinox data, which we suggest being generated by the transport of plasma from the Weddell Sea anomaly (WSA). We also highlight and show the evolution of a midlatitude summer nighttime anomaly (MSNA) during the June solstice data in the North Atlantic sector. Our results give new insights into these two anomalies, where we show that they are stronger with increasing solar flux levels and that they last until the early morning. These latter results are not consistent with those from previous studies.

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Section: Ionospheric Density Climatology At the Iss Heightsupporting

confidence: 84%

Ion Density Climatology Based on FPMU Measurements on Board the International Space Station

Laranja,

Fejer,

Ridenti

et al. 2023

JGR Space Physics

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“…The GOLD mission has been making synoptic disk observations of daytime thermospheric composition and temperature since late 2018. The studies using the GOLD data include temperature changes during various geomagnetic activities (Laskar et al., 2021); composition changes during a solar eclipse (Aryal et al., 2020), nighttime ionospheric structures (Eastes et al., 2023; Karan et al., 2020), and geomagnetic storms (Cai et al., 2020, 2021, 2023; Correira et al., 2021; Gan et al., 2020a; Karan et al., 2023). Lower and upper atmosphere coupling via atmospheric waves has also been observed by the GOLD mission (Gan et al., 2020b; Gan, Qian, et al., 2023; Gan, Oberheide, et al., 2023; Krier et al., 2021; Oberheide et al., 2020, etc.).…”

Section: Introductionmentioning

confidence: 99%

Tongan Volcanic Eruption Induced Global‐Scale Thermospheric Changes Observed by the GOLD Mission

Aryal

Gan

Evans

et al. 2023

Geophysical Research Letters

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The Hunga Tonga-Hunga Ha'apai volcano had been active with minor eruptions since 20 December 2021 (see https://www.ngdc.noaa.gov/hazard/dart/2022tonga.html). A major eruption that occurred on 15 January 2022, at 4:15 UT was visible from space. The underwater eruption triggered a tsunami that traveled throughout the Pacific Ocean and, unfortunately, caused fatalities (Needham & Menon, 2022). The eruption also released an enormous amount of energy (∼10-20 EJ estimated by Wright et al., 2022) into the atmosphere. In addition to the lower atmosphere, the eruption's signature was also detected in the mesosphere (

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“…TEC is not required as a data product for the Fengyun‐4C mission (neither for the GOLD mission), likely because FUV remote sensing is thought to be of low accuracy for the retrieval of TEC. In the literature, the GOLD observations have been used to study the equatorial ionosphere mainly through examination of the intensity maps of the OI 135.6 nm emission, and the coincided GNSS measurements were used whenever TEC maps are needed for the investigations (e.g., Aa et al., 2020; Cai et al., 2020; Eastes et al., 2023; Laskar et al., 2020; Park et al., 2022). Indeed, the GNSS network has been considered for decades as the most accurate means for TEC measurements.…”

Section: Resultsmentioning

confidence: 99%

Inferring the Ionospheric State With the Far Ultraviolet Imager on the Fengyun‐4C Geostationary Satellite: Retrieval Algorithm and Verification

Qin,

Liu,

Yin

et al. 2023

Earth and Space Science

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The Multiband Ultraviolet Spectrum Imager (MUSI) is an optical remote sensing instrument scheduled to launch on the Fengyun‐4C meteorological satellite in 2024. MUSI is designed to measure the airglow emissions between ∼120 and 160 nm above the East Asia and Pacific region from a geostationary orbit to infer ionospheric parameters. Here we develop a lookup‐table algorithm for retrieving the peak electron density (nmF2) and the Total Electron Content (TEC) from nighttime observations of the OI 135.6 nm emission. The algorithm takes into account the north‐south asymmetry of the equatorial ionization anomaly and the atmospheric variations with solar activity and local time. Analysis of synthetic observations shows that the assumptions made in the algorithm only lead to ∼2%–4% uncertainties in the retrievals under the modeled ionospheric conditions. The algorithm is verified by retrieving nmF2 and TEC from the Global‐Scale Observations of the Limb and Disk (GOLD) mission and comparing with coincided radio measurements. The comparison indicates almost negligible systematic differences (typically less than ∼3%) between the GOLD and the ionosonde nmF2, which are within the error limit of the GOLD retrievals. The accuracy of the GOLD TEC retrievals is shown to be comparable to (or in some sense even better than) that of the measurements from the Global Navigation Satellite System. Several simplified yet robust retrieval methods are also developed, which can be readily implemented for both existing and upcoming missions. Our results promote far ultraviolet (FUV) remote sensing to be a key technology for accurate determination of the ionospheric state.

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GOLD Observations of Longitudinal Variations in the Nighttime Equatorial Ionization Anomaly (EIA) Crests' Latitudes

Cited by 11 publications

References 50 publications

Ion Density Climatology Based on FPMU Measurements on Board the International Space Station

Ion Density Climatology Based on FPMU Measurements on Board the International Space Station

Tongan Volcanic Eruption Induced Global‐Scale Thermospheric Changes Observed by the GOLD Mission

Inferring the Ionospheric State With the Far Ultraviolet Imager on the Fengyun‐4C Geostationary Satellite: Retrieval Algorithm and Verification

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