PROBLEMS OF GEOCOSMOS

Proceedings of the 7th International Conference "Problems of Geocosmos" (St. Petersburg, Russia, 26-30 May 2008)
Results of calculation of orbit projections were used to determine the time when satellites could cross the
disturbed zone. And this times approximately are: Cluster 1 among 23:10 and 23:30 UT, Cluster 2 23:20 –
23:40, Cluster 3 22:00 – 22:20 UT and Cluster 4 23:30 – 23:40.
It is supposed that effect from heating can be seen in particle data and first of all in electron data from
PEACE: Plasma Electron And Current Experiment instrument. And it is supposed that the frequency of
modulation of heating facility 0.0017 Hz ( period 10 minutes) can be detected in the data.
Fig. 2 Results of window fourier analysis for variations of electron density for “expected” frequency 0.0017
Hz. Horizontal line shows approximate time of satellite crossing the heated spot.
The window fourier analysis (Fig.2) of electron density variation data shows the time evolution of
“expected” frequency (0.0017 Hz). The analysis is made for Cluster 1, Cluser 2, Cluser 4. For Cluser 3 the
PEACE instrument didn’t work during considered period. It is shown that there is some amplification of
amplitude during satellites crossing the heated tube for all satellites. There is a significant effect in Cluster 4
in comparison with others that possibly can be explained by closer crossing by Cluster 4 to the center of spot.
All pictures show rather complicated behavior of amplitude at 0.0017 Hz and it’s not obvious to make a
decision. But every line has a tendency to decrease to the end of crossing the disturbed region and have a
local maximum: Cluster 1 about 23:10, Cluster 2 – 23:35, Cluster 4 – 23:40. These local maximums perhaps
can correspond to real satellite crossings, but it’s not so obvious however. But if so, the real disturbed zone is
rather smaller than predicted by Fig.1, but lies within calculated boundaries that shows good coincidence
with orbit modeling.
Electric field data analysis
According to supposition that heating can provide enhanced conductivity region in ionosphere which can
produce field aligned currents analysis of duskward electric field obtained from EFW (Electric Field and
Wave experiment) instrument was made Maulini et al (2004).
It is clearly seen in Fig. 3 that some disturbances starts in approximately time corresponding to the
satellites crossing the disturbed region according to orbit modeling. Line across the graphics corresponds to
10 minute period (0.0017 Hz – frequency of transmitter). Cluster 1 figure shows set of disturbances started at
right time, but as to period axis there is no maximum at 10 minute period. One can say that Cluster 1 doesn’t
cross disturbed region or effect of heating is overlapped by other effect at shorter period. The most
significant effect is in Cluster 2 data and it close to Cluster 4. According to Fig.1 they cross disturbed region
roughly at the same time and distance. Maximum of wavelet coefficients is approximately near 10 minute
period so it is possible to conclude that heating can provide such effect in the data. As to Cluster 3 it is seen
from Fig.1 that it crosses the disturbed region much earlier and distantly than other and this behavior seems
to correspond to its wavelet figure: the level of data is less than other but there is maximum in coefficient in
vicinity of 10 minutes period line. One can conclude that it detects heating effect but near the boundary of
disturbed zone. In contrary to Cluster 1 Cluster 3 could not be affected by some other effect at lesser period,
but maximum at about 5 minutes is also seen at Cluster 3 wavelet figure.
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