Meanwhile, scientists 19, 20 find that the lunar phase, which is defined as the relative position among the Sun, the Moon, and the Earth, can significantly modify the EIA appearance. 14 studied the ionosphere response to SSWs and observed the pattern of total electron content (TEC) enhancements in the morning sector and suppressions in the afternoon sector at EIA latitudes during SSW occurred on 19–31 January 2009. Recent 10-year studies have shown that lunar tides get enhanced as a result of SSWs related changes in the background lower and middle atmosphere, which then goes on to impact the ionosphere through the dynamo mechanism 7– 18. During SSWs, the stratospheric polar temperature rapidly increases, the normally eastward winds in the high-latitude stratosphere (60° N and 10 hPa) decelerate, potentially reversing direction, and the structure of the polar vortex changes significantly 4– 7. Stratospheric sudden warmings (SSWs) are remarkable dynamical disturbances in the high-latitude stratosphere during winter 4– 6. Thus, both lunar phase and SSWs can significantly modulate the appearance time of EIA crest and ionospheric plasma dynamics and structures.Įquatorial ionization anomaly (EIA) is the most pronounced low-latitude ionospheric structure, featured by two dense bands of electron density around ± 12°N magnetic latitude straddling the magnetic equator 1– 3. A statistical analysis shows that SSWs can also significantly cause the early appearance of EIA crests, regardless of the lunar phase. Results show that the EIA crest appearance time on new/full moons (first/third quarters) leads (lags) that of the overall 14-year average, which causes a pattern of TEC morning enhancements (suppressions) and afternoon suppressions (enhancements). The most prominent feature in the ionosphere is the EIA, characterized by two enhanced TEC crests at low latitudes straddling the magnetic equator, which can be used to observe ionospheric plasma dynamics and structures. The total electron content (TEC) of global ionosphere maps is employed to examine responses of the equatorial ionization anomaly (EIA) crests to lunar phases and twelve SSW events during 2000–2013. This study examines the ionosphere response to gravitational forces of the lunar phase and dynamical disturbances of the stratospheric sudden warmings (SSWs).
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