Solar cycle variation of the ionization by cosmic rays in the atmosphere
at the mid-latitude region of Athens
Makrantoni, P.
Mavromichalaki, H.
Paschalis, P.
In this study, the ionization rate in the atmosphere induced by solar
and galactic cosmic rays is calculated for the region of Athens (Greece)
during the time period from 1996 to 2019 covering the last two solar
cycles 23 and 24. In order to compute the cosmic ray induced ionization,
the corresponding model of the University of Oulu was used along with
its new version which is extended to the upper atmosphere. This model
has been applied to the entire atmosphere, i.e., from the atmospheric
depth of 0.00 g/cm(2) corresponding to the upper limit of the atmosphere
(similar to 40 km), to that one of 1025 g/cm(2) corresponding to the
Earth's surface. Furthermore, an application has been made as a function
of rigidity and geomagnetic latitude, from 0.1 GV (similar to 90(circle)
polar regions) to 14.9 GV (similar to 0(circle) equatorial regions).
Specifically, we focus at the region of Athens that is a middle latitude
one, located at 38(circle)N geographic latitude, and cosmic ray
intensity is recorded by the sea level (260 m) neutron monitor station
of the National and Kapodistrian University of Athens. Cosmic ray
particles with a vertical cut-off rigidity of 8.5 GV are measured in
real time and magnetospheric effects of the cosmic ray intensity with
the maximum amplitude in the north hemisphere, are often observed. A
comparison of the calculated cosmic ray induced ionization in this
region with the ionization of polar and equatorial regions during the
different phases of the solar cycles 23 and 24, is performed. A seasonal
variation of this ionization during all the examined period is for first
time observed. Obtained results are discussed in terms of Space Weather
applications.
(EN)
