The Latitudinal Variation and Hemispheric Asymmetry of the Ionospheric Lunitidal Signatures in the American Sector During Major Sudden Stratospheric Warming Events

Abstract

The ionospheric perturbations during sudden stratospheric warming events (SSWs) have attracted broad attention recently, including depressions and enhancements (

Latitudinal and interhemispheric differences of the ionospheric semi-diurnal lunitidal perturbations during the 2009 Arctic sudden stratospheric warming event in the eastern Asia–Australia sector

“…Figure 6a, b shows that the latitudinal and interhemispheric differences of the A M2 variation are similar in the eastern Asia-Australia and American sectors as described hereinabove. Our previous paper (Liu et al, 2021) suggested that the latitudinal difference in the low latitude is largely contributed by the summer-winter meridional wind effect on the equatorial plasma fountain. We also discussed the possible contributions from the local geomagnetic configuration since the geomagnetic equator in the American sector is in the southern hemisphere.…”

“…6c, d for facilitating quantitive comparisons between the eastern Asia-Australia and American sectors. The American results were calculated with the same method described in section 2, but with CEDAR Madrigal TEC map data (Rideout and Coster, 2006;Liu et al, 2021).…”

“…It is worth noting that there is a unique ionospheric phenomenon named Weddell Sea Anomaly (WSA) (Penndorf, 1965;He et al, 2009;and references therein) in the American southern middle latitude. Liu et al (2021) discussed the possible M2 wind modulation on the nighttime TEC in the WSA region during the 2009 SSW. The WSA is primarily attributed to the combined effect of the zonal wind and the positive geomagnetic declination which contributes to the geomagnetic northward wind that sustains the F-region plasma density (Penndorf, 1965;He et al, 2009;and reference therein).…”

“…The latitudinal and interhemispheric differences of the ionospheric M2 perturbations have drawn much attention (Goncharenko et al, 2010(Goncharenko et al, , 2013Liu et al, 2011Liu et al, , 2021Fagundes et al, 2015;Mo et al, 2017;Pedatella and Maute, 2015;Yue et al, 2010). Such differences were considered to be related to different background features and coupling mechanism.…”

“…The direct upward penetration of lower-atmosphere waves and their in situ dynamics in the ionosphere are also considered, especially in the middle and high latitudes (Goncharenko and Zhang, 2008;Pedatella and Maute, 2015). With ground-based TEC data across the American continents, Liu et al (2021) analyzed the latitudinal distribution of the M2 perturbation enhancement during three major SSWs. The observed distribution is mainly attributed to the meridional wind effect on the equatorial plasma fountain while the direct penetration mechanism may be important in the southern middle latitudes.…”