DISTRIBUTION OF THE OCCURRENCE OF THE INTENSIVE IONOSPHERE SCINTILLATIONS ON THE OBSERVATIONS OF THE COSMIC RADIO SOURCES AT THE DECAMETER WAVE RANGE

Анотація

Effect of scintillations arises in the result of
interaction of radio signal from the cosmic radio source with
irregularities of ionosphere plasma which appears at the
registration of observations as amplitude fluctuations.
Wherein fluctuations of the different intensities and with the
different long time periods can be observed. Scintillations of
large intensity and with large characteristic times (periods)
take an interest because its influence on records of the radio
sources is very essential and can distort the record shape. In
this case there is a need to consider the presence of the
intensive fluctuations. In this sense it might be useful to
investigate the frequency of occurrence of the intensive
scintillation. Processing of the radio sources records was
carried out on the observations of power cosmic radio sources
at the passage through direction pattern of the radio telescope
URAN-4 at frequencies 20 and 25 MHz during 1998-2007.
Record's characteristics were obtained including ionosphere
scintillation parameters. Also records with scintillations of
large intensity and with long periods were marked. In this
work daily distribution of intensive scintillations was
analyzed. It was showed that occurrence of intensive
scintillations changes in limits of 4-26% and it is larger on the
lower frequency. Dependence of occurrence of scintillations
from angle between direction on the radio source and line of
geomagnetic field in the observation place was found. It was
obtained that the maximum of the occurrence of the intensive
scintillations for all observed radio sources appears on the
nighttime of the day. Also local maximums of frequency of
occurrence are exist which may be associated with the
moments of sunrise and sunset