Searching for effects caused by thunderstorms in midlatitude sporadic E layers

Abstract

Possible thunderstormsporadic E (Es) layer coupling effects are investigated during two measurement periods, one in 2013 and one in 2014. The analysis was based on ionospheric observations obtained from a Digisonde at Pruhonice, the Czech Republic, an ionosonde at Nagycenk, Hungary, and a 3.59 MHz five-point continuous HF Doppler system located in the western part of the Czech Republic. The latter is capable of detecting ionospheric wave-like variations caused by neutral atmospheric waves generated by thunderstorms. The present study searches for possible impacts on Es layers caused by the presence of two active thunderstorms: one passing across the Czech Republic (11:00-01:00 LT). During these two time periods, presence and parameters of Es layer were inferred from ionograms, recorded every minute at Pruhonice and every two minutes at Nagycenk, whereas concurrent lightning activity was monitored by the LINET detection network. In addition, transient luminous events (TLEs) were also observed during both nights from Sopron, Hungary and from Nýdek, the Czech Republic. A noticeable fact was the reduction and disappearance of the ongoing Es layer activity during part of the time in both of the traversing thunderstorms. The analysis indicated that the critical frequency foEs dropped below ionosonde detection levels in both cases, possibly because of thunderstorm activity effects. This option, however, needs more case studies in order to be further substantiated. Fig. 2. The geographic locations of the lightning strokes, which occurred nearPruhonice during the observation period from . 06. 20. 19:00 to 2013 are represented by dots. The occurrence time of lightning strokes is color coded, indicating that the storm moves towards northwest, over the western Czech Republic. The blue stars show the locations of the sprite-causative +CG discharges. The blue and violet triangles show the locations of the digisonde at Pruhonice, and the sprite camera at Sopron, respectively.

Response to Reviewers

“…It shows the similar tendency of tide-period height. With the decrease in the Es height below 100 km and the occurrence of the maximum neutral Na layer during thunderstorms, a remarkable reduction of relative foEs and then disappearance of the Es with a decrease in occurrence rate are observed, as reported in Barta et al (2017). Furthermore, Figure 2b shows the Es height is controlled not only by the diurnal tide but also by the semidiurnal tide.…”

“…The atmospheric tide is a dominant dynamical process in the MLT and plays dominant roles in the formation and dynamical processes of the intensification of metallic layered phenomena above thunderstorms." 2/ Page 2. line 15.: Barta et al 2015 performed Superposed Epoch Analysis (SEA) Barta, V., Pietrella, M., Scotto, C., Bencze, P., Sátori, G., (2015) Thunderstorm-related variations in the sporadic E layer around Rome, Acta Geodaetica et Geophysica, 50:261-270 However, Barta et al 2017 reported two case studies which was based on highly sampled ionosonde data, Doppler measurement, and ligthning and TLE records. Thus it was a different type of analysis than the previously reported studies, which based on Superposed Epoch Analysis.…”

“…Printer-friendly version Discussion paper (2015) and Barta et al (2017) in the introduction more carefully.…”

“…Please see page 2 lines 24-26. "Recently, Barta et al (2017) reported two case studies of mesoscale convective storms that moved through two ionosonde stations, in which a reduction and then disappearance of the ongoing Es layer were observed. It is a non-statistical study, based on highly sampled ionosonde data, Doppler measurement, and lightning and TLE records.…”

The intensification of metallic layered phenomena above thunderstorms through the modulation of atmospheric tides

“…It was the first paper to reveal an enhancement of E s layer which occurs ∼6 h and ∼30 h after lightning. After that, more studies applied the same methodology of SEA on lightning and E s layer measurements using the hourly lightning events as trigger times (Johnson and Davis, 2006;Davis and Lo, 2008;Barta et al, 2013;Yu et al, 2015;Barta et al, 2017). Nowadays, the mechanism responsible for the ionospheric E s perturbations above thunderstorms is not well understood.…”