  Possible thunderstorm - sporadic 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 on June 20,
2013 (19:00 - 01:00 LT), and one through Hungary on July 30, 2014 (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 Nydek, 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.
