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

Abstract

The ionosphere exhibits some characteristic perturbations during sudden stratospheric warming (SSW) events, of which the mechanism is not thoroughly understood. This study focuses on the latitudinal and interhemispheric differences of the enhanced semi-diurnal lunitidal (M2) perturbations related to SSW using total electron content calculated from the network of Global Navigation Satellite System and ionosonde data in the eastern Asia–Australia sector during the January 2009 SSW. Our results show that the most distinct M2 perturbations in the northern and southern hemispheres occur near the Equatorial Ionization Anomaly crest regions around ± 15° geomagnetic latitudes, but corresponds to different moon phases, respectively. Clear M2 perturbations extend to middle latitudes only in the southern hemisphere and have another local maximum in the southern middle latitude. Such latitudinal and interhemispheric features of ionospheric M2 perturbations in the low latitude in the eastern Asia–Australia sector are similar as those in the American sector during the same SSW event. This supports previous suggestion that such latitudinal and interhemispheric differences in the low latitude can be primarily explained by the summer–winter thermospheric wind modulation on equatorial plasma fountain and thus emphasize its role in the vertical coupling process of M2 perturbation. The clear differences of M2 perturbations in the southern middle latitude between the eastern Asia–Australia and American sectors indicate that the thermospheric circulation related to the Weddell Sea Anomaly may have influence on the lower atmosphere–ionosphere coupling. Graphical Abstract

Ionospheric Semidiurnal Lunitidal Perturbations During the 2021 Sudden Stratospheric Warming Event: Latitudinal and Inter‐Hemispheric Variations in the American, Asian‐Australian, and African‐European Sectors

“…The largest A M2 in the Northern and Southern Hemispheres appear at about 10°∼15°N and 25°∼30°S geomagnetic latitudes, respectively, and clear PSSD signatures and A M2 (and A M2 ′) enhancements extend to middle latitudes only in the Southern Hemisphere. Such latitudinal and inter-hemispheric differences resemble those during the 2009 SSW in the American and Asian-Australian sectors (Liu et al, 2021(Liu et al, , 2022. During Arctic SSW (boreal winter), the F-region trans-equatorial wind blows northward from the sub-solar point.…”

“…Goncharenko et al (2013) reported stronger TEC PSSD disturbances in the Northern Hemisphere (15°N geomagnetic latitude) than in the Southern Hemisphere (15°S geomagnetic latitude) in the American, eastern African, and Asian sectors during the 2013 SSW. With TEC observations in continuous latitudinal bands during the 2009 SSW, Liu et al (2021Liu et al ( , 2022 showed that the A M2 crest in the Northern Hemisphere (15°N geomagnetic latitude) is stronger than that in the Southern Hemisphere (20°S geomagnetic latitude) in both the American and Asian-Australian sectors. In contrast, the current study shows that the A M2 crest during the 2021 SSW is larger in the Southern Hemisphere than in the Northern Hemisphere in the American and Asian-Australian sectors.…”

“…With TEC observations in continuous latitudinal bands during the 2009 SSW, Liu et al. (2021, 2022) showed that the A M2 crest in the Northern Hemisphere (15°N geomagnetic latitude) is stronger than that in the Southern Hemisphere (20°S geomagnetic latitude) in both the American and Asian‐Australian sectors. In contrast, the current study shows that the A M2 crest during the 2021 SSW is larger in the Southern Hemisphere than in the Northern Hemisphere in the American and Asian‐Australian sectors.…”

“…The vertical transportation of the M2 perturbations in the middle and high latitudes were mainly attributed to the direct penetration and in‐situ modulation of the tidal wave (Goncharenko & Zhang, 2008; Park & Lühr, 2012; Pedatella & Maute, 2015). Our previous studies (Liu et al., 2021, 2022) found that the inter‐hemispheric differences of the F‐region M2 perturbations during the 2009 SSW are similar in the low‐latitude American and Asian‐Australian sectors and attributed this result to the inter‐hemispheric asymmetry of the equatorial plasma fountain driven by the meridional wind. Nevertheless, we noted that the M2 perturbations in the Southern‐Hemisphere middle latitude were different between the American and Asian‐Australian sectors during the 2009 SSW while the causes are not thoroughly understood.…”

The Latitudinal and Longitudinal Variation of the Semidiurnal Lunar Tide in the Ionosphere During 2013

“…Most of studies about latitudinal and longitudinal variation of ionospheric M2 perturbations are focused on the SSW period (Fagundes et al, 2015;Fejer et al, 2010;Goncharenko et al, 2013;Jonah et al, 2014;Liu et al, 2021Liu et al, , 2022aMo and Zhang, 2018). In latitudinal variation, Goncharenko et al (2013) and Liu et al (2022a) reported that the TEC perturbations in the NH are stronger than these in the American longitudinal sector during 2009 and 2013 SSW exhibiting hemispheric asymmetry. However, the M2 amplitudes crest during the 2021 SSW are larger in the southern hemisphere (SH) than in the NH in the American and Asian-Australian sectors, which are contrast to these during 2009 and 2013 SSW, indicating that the hemispheric asymmetry is different between different SSW events (Liu et al, 2022b).…”