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80.0
40.0
0.0
40.0
Eperp.
80.0
40.0
0.0
40.0
80.0
Eperp.
40.0
0.0
40.0
Eparallel
80.0
0.750
0.950
1.150
1.350
1.550
1.750
seconds
Time 5:53:54.75 To 55.75 UT, Altitude 294 km
Figure 7.21
Vector electric fields over a thunderstorm. [After Kelley et al. (1990). Repro-
duced with permission of the American Geophysical Union.]
mode wave. Four rockets were launched by Cornell University over thunder-
storms fromWallops Island (Kelley et al., 1990; Siefring and Kelley, 1991; Baker
et al., 1996; Kelley et al., 1997). One of the most intriguing, and as yet not
understood, features observed in these launches is a parallel electric field accom-
panying each strike. An example of electric fields observed in the ionosphere at
294 km altitude is shown in Fig. 7.21. The field strength is as high as 50mV/m,
but it is a far cry from the 5V/m seen the same distance away along the ground in
the earth-ionosphere waveguide (Kelley and Barnum, 2009; Vlasov and Kelley,
2009). The dissipated energy heats the mesospheric electrons. On one occasion,
keV electrons were detected over a thunderstorm-rich hurricane with an associ-
ated electric field burst (Burke et al., 1992). The parallel electric field component
observed by the rockets rides on the leading edge of the wave front, which trav-
els at nearly the speed of light. These parallel fields may be associated with an
ac conductivity,
, associated with the leading edge. Large-amplitude
waves launched from the ground have produced particle acceleration and heat-
ing at midlatitudes at HF frequencies (Djuth et al., 1999; Kagan et al., 2000;
Vlasov et al., 2005), which may be a similar process.
σ
ac
=
j
ωε
7.9 Nonlinear Mesospheric Waves
7.9.1 Observations
Another new and interesting mesospheric phenomenon was first observed over
Haleakala, Hawaii, on October 10, 1993 (Taylor et al., 1995). A summary of
the event is shown in Fig. 7.22. The feature was first detected coming in from
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