Wave-3 and wave-4 patterns in the low- and mid-latitude ionospheric TEC

Sicheng, Wang; Huang, Shucai; Fang, Hanxian

doi:10.1016/j.jastp.2015.07.002

Cited by 11 publications

(19 citation statements)

References 40 publications

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“…The leading nonmigrating tidal components with zonal wavenumber (ZWN) responsible for such wavenumber‐4, wavenumber‐3, and wavenumber‐2 longitudinal wave pattern is believed to be the dominating diurnal eastward (DE3; ZWN = 3), diurnal eastward (DE2; ZWN = 2), and semidiurnal westward (SW4; ZWN = 4), respectively, though the other trivial components do exist (Forbes et al, ; Pedatella et al, ). Hence, the present observations reinforce earlier observational and modeling studies on the appearance of longitudinal wave‐like pattern in the equatorial and low‐latitude ionospheric electron density profiles, peak height parameters (Brahmanandam et al, ; Kil et al, ; G. Liu, Immel, et al, ; L. Liu, Wan, et al, ; Lühr et al, ; Pancheva & Mukhtarov, ), drift velocity (Hartman & Heelis, ; Huang et al, ; Kil et al, ; Ren et al, ), thermospheric wind and temperature (Husler et al, ; Ren et al, ), TEC (Lin, Hsiao, et al, ; Scherliess et al, ; Wan et al, ; Wang et al, ; Zhong et al, ), and in the topside ionosphere (Bankov et al, ; Hawkins & Anderson, ; Kakinami et al, ). The daytime wavenumber‐4 (equinox) and wavenumber‐3 (winter solstice) longitudinal structure is also reported by Scherliess et al () from 13 years of TEC data retrieved from the TOPEX/Poseidon altimeter.…”

Section: Equatorial and Low‐latitude Features Of Bottomside Profile Psupporting

confidence: 89%

Global Longitudinal Behavior of IRI Bottomside Profile Parameters From FORMOSAT‐3/COSMIC Ionospheric Occultations

2018

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The bottomside thickness and shape (B0 and B1) are the critical key elements for depicting a realistic electron density profile in the International Reference Ionosphere (IRI) model. We investigated their longitudinal variability using a large database of FORMOSAT‐3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) electron density profiles covering the period 2006–2015 from which these parameters are derived using a simple analytic Chapman least squares fitting. The parameters are then compared with the IRI‐2012 submodels, that is, Bil‐2000, Gul‐1987, and ABT‐2009 during different seasons and solar activity. Besides apparent adherence of B0 to the equatorial region, the opposite occurrence pattern of maximum B0 to that of NmF2 is realized, manifesting semiannual distribution and hemispheric asymmetry. Unlike NmF2, the presence of single anomaly crest in B0 in all seasons except March equinox and their leading local time stamps are among the key observations. In spite of regular representation of IRI submodels during equinox, the performance of Gul‐1987 seems to be inferior during solstice with respect to geomagnetic field and equatorial electrodynamics, thereby depicting an erroneous distribution of B0. The striking wave‐like feature in B0 longitudinal variability is also revealed indicating its possible connection with the nonmigrating diurnal/semidiurnal tides. Moreover, the solar activity effect on B0 appears to be relatively higher over the Asian and Pacific longitudes (60–150°E). Although speculations are made over B1 variability, its complete longitudinal characteristics are indistinguishable in our results, except the subordinate magnitude as compared to IRI estimations. The important findings from this study may reinforce the understanding of bottomside variability and future improvements in IRI.

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Section: Equatorial and Low‐latitude Features Of Bottomside Profile Psupporting

confidence: 89%

Global Longitudinal Behavior of IRI Bottomside Profile Parameters From FORMOSAT‐3/COSMIC Ionospheric Occultations

2018

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“…TW3 shows a strong positive relation around the magnetic equator and a weak to moderate positive relation along other latitude. Immel et al, 2006;Lin, Wang et al, 2007;Pedatella et al, 2012;Sagawa et al, 2005;Wang et al, 2015;Zhou et al, 2016) reported that these nonmigrating tidal waves in the ionosphere are likely associated with the longitudinal wave-3 or wave-4 structure in the neutral atmosphere.…”

Section: Solar Activity Dependence Of Wave Powermentioning

confidence: 99%

“…Use least squares data fitting to obtain wave modes Wang et al (2015; W3/W4 structures) Global ionosphere maps (JPL) DE2 (n = 1, s = 2), SPW3 (n = 0, s = ±3), SPW4 (n = 0, s = ±4)…”

Section: Introductionmentioning

confidence: 99%

Ionospheric Tidal Waves Observed From Global Ionosphere Maps: Analysis of Total Electron Content

et al. 2018

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The monthly, seasonal, yearly, and latitudinal variations of ionosphere tidal waves are studied based on the total electron content (TEC) data from global ionosphere maps. We use two‐dimensional (longitudinal, −180°E to 180°E; and time, 10 days) Fourier transform of TEC variations along different latitude to obtain all wave modes for the period from 18 November 2002 to 15 October 2014. The wave modes can be classified as westward propagating (eastward propagating and standing) waves with 85.8–97.3% (2.3–10.0% and 0.4–4.2%) of total power. The wave modes are found to consist of migrating waves with power 75–94% and nonmigrating waves with 5.8–25%. The migrating waves are dominated by diurnal migrating tide (DW1, 69.9–89.4%), semidiurnal migrating tide (SW2, 0.5–4.3%), and terdiurnal migrating tide (TW3, 0.2–1.9%). Also, the total wave power and powers of DW1 and SW2 peak along magnetic latitude 10°N and decrease with increasing magnetic latitude. The power of TW3 peaks along the magnetic equator and decreases with increasing magnetic latitude. We also found that the wave powers of DW1 and SW2 obtained from TEC data are very similar to the wave powers obtained from the ionospheric density with a profile of sech2 solitary wave. The observed migrating amplitudes are stronger in equinoxes and weaker in solstices. For the nonmigrating tides, we simultaneously identify the wave modes and wave powers, which contribute to wave‐1, wave‐2, wave‐3, wave‐4, and wave‐5 peak structures in the local time frame. The total wave power associated with TEC variations increases with solar activity (sun spot number).

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“…The ion-neutral coupling is only a minor contributor. Wang et al [50] used the JPL global ionospheric maps from 1999 to 2013 to analyze the tidal patterns in the ionospheric TEC. The space-time spectral analysis results showed significant seasonal variations in the amplitudes of DE2, DE3, SPW3, and SPW4.…”

Section: Ionospheric Climatology and Structuresmentioning

confidence: 99%