RESEARCH DATA FROM A. CHILINGARIAN AND COLLEAGUES UPDATE UNDERSTANDING OF PLANETARY SCIENCE

Science Letter
November 3, 2009

"Interplanetary coronal mass ejections (ICMEs) dominate the intense
geomagnetic storm (GMS) occurrences, and simultaneously, they are
correlated with the variations of the spectra of particles, ranging
from the isothermal solar wind ions to GeV energy protons and fully
stripped nuclei. The aim of this paper is to get more insight in
the correlations of the ICME parameters with geospace parameters,
including the Dst index and the secondary cosmic ray flux," researchers
in Yerevan, Armenia report (see also Planetary Science).

"Our observations of GMS occurring during the 23rd solar activity cycle
demonstrate that the count rate increase during GMS occurs coherently
(or up to 1 h in advance) with Dst changes. We show that the ratio
between the increases of neutron and charged fluxes is approximately
constant in a large range of the GMS severity (-470 to 20 nT). The
neutron flux always undergoes larger changes compared to the charged
component. The difference in peak amplitude can be explained by the
fact that lower-energy primary particles produce neutrons compared
to the primaries that generate electrons and muons reaching the
Earth’s surface. We also illustrate that the main driver of GMS is
the southward Bz component of the magnetic field of the ICME," wrote
A. Chilingarian and colleagues.

The researchers concluded: "Thus the information on the flux changes
for different secondary particles helps to "test" the models of the
interplanetary magnetic field and the magnetosphere for understanding
of the level of disturbance and the specific mechanisms leading to
cutoff rigidity reduction."

Chilingarian and colleagues published their study in the Journal of
Geophysical Research – Space Physics (Cosmic ray intensity increases
detected by Aragats Space Environmental Center monitors during the
23rd solar activity cycle in correlation with geomagnetic storms.

Journal of Geophysical Research – Space Physics, 2009;114():9107).

For additional information, contact A. Chilingarian, Yerevan Physics
Institute, Cosm Ray Division, Alikhanyan Bros 2, Yerevan 36, Armenia.

Publisher contact information for the Journal of Geophysical Research –
Space Physics is: American Geophysical Union, 2000 Florida Avenue NW,
Washington, DC 20009, USA.

From: Emil Lazarian | Ararat NewsPress