Quasi-16-day periodic meridional movement of the equatorial ionization anomaly

Abstract

Abstract. Based on the daytime location of the equatorial ionization anomaly (EIA) crest derived from GPS observations at low latitude over China during the 2005-2006 stratospheric sudden warming (SSW), a quasi-16-day periodic meridional movement of EIA crest with the maximum amplitude of about 2 degrees relative to the average location of EIA crest has been revealed. In addition, periodic variations that are in phase with the meridional EIA movement are also revealed in the equatorial electrojet (EEJ) and F2 layer peak height (hmF2) over Chinese ionosonde stations Haikou and Chongqing. The quasi-16-day periodic component in Dst index is weak, and the 16-day periodic component does not exist in F10.7 index. Such large-scale periodic meridional movement of EIA crest is likely related to the globally enhanced stratospheric planetary waves coupled with anomalous stratospheric zonal wind connected with SSW. In addition, such large-scale periodic movement of EIA should be global, and can affect the ionospheric morphology around the low-latitude belt near the EIA region. Further case analysis, simulation and theoretical studies must proceed in order to understand the periodic movements of EIA connected with the different periodic atmospheric variations.

Lunar Tidal Modulation of Periodic Meridional Movement of Equatorial Ionization Anomaly Crest During Sudden Stratospheric Warming

“…This 14‐ to 15‐day oscillation in China EIA region had been found in our prior studies, which were termed the quasi 16‐day period according to the naming rules of quasi 16‐day period in atmosphere. As confirmed by our previous research, this 14‐ to 15‐day periodic movement in EIA crest during this SSW event should not be of solar/magnetic activity origin (Mo et al, , ). Moreover, the amplitudes of 14‐ to 15‐day oscillations in China sector, in order of highest to lowest, are during 2009, 2006, and 2003 SSW period.…”

“…Second, the peaks of 14‐ to 15‐day waves in the location of EIA crest are always 4–6 days later than the dates of new moon or full moon. Further, 14‐ to 15‐day waves in the location of EIA crest are in‐phase with that in EEJ and h m F 2 (Figure ) (Mo et al, ), indicating that in the peaks of EEJ and h m F 2 , EIA crest locations happen 4–6 days after new moon or full moon. That consistent phase lag was relative to new moon or full moon had also been revealed in EEJ, plasma drifts, and TEC due to semidiurnal lunar wave effect (Fejer et al, ; Goncharenko et al, ).…”

“…The ionospheric vertical TEC will reach the maximum at EIA peak point when observation arcs pass through the EIA crest region, so that the location and local time of the EIA crest can be determined by the ionospheric vertical TEC curve derived from every continuous observation arc. The details of this process can be found in our previous work (Mo et al, ). Figures a and b, a and b, and a and b show the MLAT of EIA crests collected from GPS observations (EIA peak point marked with the black dot, daily average marked with the solid line, and total average marked with the blue dashed line) during SSW events in 2003, 2006, and 2009.…”

Ionospheric response to the 2009 sudden stratospheric warming over the equatorial, low, and middle latitudes in the South American sector

“…Earlier studies have demonstrated that the largest variations in VTEC during SSW are observed at the crests of the EIA [Goncharenko et al, 2010a;Liu et al, 2011], and the location of the crests can vary periodically by several degrees in latitude [Mo et al, 2014]. In addition, the difference from one station to another is related with superimposed perturbation caused by MSTID and/or PW disturbances.…”

Impact of Stratospheric Sudden Warming on the Occurrence of the Equatorial Spread‐F

“…The most commonly observed planetary waves to which atmosphere readily responds are those having periodicities 2, 5, 10, and 16 days (Salby, 1981;Williams & Avery, 1992). It has been shown that PWs significantly influence many of the processes over the equator (Anderson & Araujo-Pradere, 2010;Goncharenko et al, 2010;Mo et al, 2014) including the PSSR and the occurrence of ESF (Abdu et al, 2006;Bertoni et al, 2010). In fact, Abdu et al (2006) have reported episodes of PW oscillations in the evening time vertical drift/zonal electric field (prereversal enhancement, PRE) over the equatorial F region, with periods ranging from~2 to~7 days concurrently with its presence in the mesospheric winds.…”