Ionospheric Irregularities and Acoustic/Gravity Wave Activity Above Low‐Latitude Thunderstorms

Abstract

Ionospheric irregularities due to plasma bubbles, scintillation, and acoustic/gravity waves are studied in the low‐latitude ionosphere in relation to thunderstorm activity. Ionospheric total electron content (TEC) measurements from the Low Latitude Ionospheric Sensor Network and lightning measurements from the World‐Wide Lightning Location Network are compared during two summer months and two winter months in 2013. Large amplitude fluctuations in TEC are found to have a strongly peaked diurnal pattern in the late evening and nighttime summer ionosphere. The maximum magnitude and coverage area of these fluctuations increases as thunderstorm area increases. Summertime midamplitude fluctuations do not exhibit the same diurnal variation but do increase in magnitude and coverage area as thunderstorm area increases. Wintertime ionospheric fluctuations do not appear to be related to thunderstorm activity. These findings show that thunderstorms have an observable effect on magnitude and coverage area of ionospheric fluctuations.

Statistical Observation of Thunderstorm-Induced Ionospheric Gravity Waves above Low-Latitude Areas in the Northern Hemisphere

“…The diurnal variation of daytime ionospheric GW activity on LS days in this study area is different to that of South America in the southern hemisphere, as reported by Lay [24]. According to Lay [24], the diurnal variation pattern on LS days is similar to that on HS days, and the magnitude of the former is always smaller than that of the latter. These distinct results may be attributed to the different study areas and employed data.…”

“…Ionospheric GW activity may show differences based on longitudinal differences between the southern region of China and South America, even though both are in low latitudes. In addition, only 11 days were used by Lay to calculate the diurnal averages of thunderstorm activity on LS days [24], while over 50 days in each year were used in this study (Table 1). Non-thunderstorm events during the 11 LS days in Lay's study [24] could have been unnoticeable, so the original variation pattern was preserved.…”

“…We used the effective grid counts to represent the coverage. If a grid cell surpassed 3 lightning stroke counts, then that cell was effective [24]; if a grid cell surpassed the amplitude threshold of ionospheric GWs, then that cell was effective. Furthermore, the maximum amplitude of each effective grid cell for ionospheric GWs during each 30 min time period was also recorded, and the average maximum amplitudes of the effective grid cells during each 30 min time period were computed ( Figure 2).…”

“…They indicated that the disturbed coverage and amplitude of ionospheric GWs scaled with thunderstorm activity, both high and low activities. In addition, Lay [24] employed a similar method to a low-latitude area in South America and concluded that thunderstorms can exert a noticeable effect on the coverage and magnitude of ionospheric GWs. Statistical studies with several months of data by Lay et al [23] and Lay [24] showed a correlation between ionospheric GWs and thunderstorm events.…”

“…In addition, Lay [24] employed a similar method to a low-latitude area in South America and concluded that thunderstorms can exert a noticeable effect on the coverage and magnitude of ionospheric GWs. Statistical studies with several months of data by Lay et al [23] and Lay [24] showed a correlation between ionospheric GWs and thunderstorm events. However, more long-term data, not only on thunderstorm days (high thunderstorms and low thunderstorms) but also on non-thunderstorm days, should be analyzed to strengthen this correlation, especially in low-latitude areas, due to complex plasma dynamics.…”