G. Fernandez

Observation of cosmic ray and electric field variations in the surface atmosphere

The results of cosmic ray observations by the CARPET instrument at CASLEO (El Leoncito, Argentina, Rc ≈ 11.8 GV) in 2006–2008 are reported. The main attention is paid to CR variations due to electric field variations in the surface atmosphere.

Analysis of cosmic ray variations observed by the CARPET in association with solar flares in 2011-2012

The CARPET cosmic ray detector was installed on April 2006 at CASLEO (Complejo Astronmico El Leoncito) at the Argentinean Andes (31.8S, 69.3W, 2550 m, Rc=9.65 GV). This instrument was developed within an international cooperation between the Lebedev Physical Institute RAS (LPI; Russia), the Centro de Radio Astronomia e Astrofsica Mackenzie (CRAAM; Brazil) and the Complejo Astronmico el Leoncito (CASLEO; Argentina). In this paper we present results of analysis of cosmic ray variations recorded by the CARPET during increased solar flare activity in 2011-2012. Available solar and interplanetary medium observational data obtained onboard GOES, FERMI, ISS, as well as cosmic ray measurements by ground-based neutron monitor network were also used in the present analysis.

Cosmic ray variations recorded by the CARPET facility on March 7, 2011

The CARPET cosmic ray detector was installed in 2006 in the Argentinean Andes at an altitude of 2550 m at the El Leoncito Astronomical Complex (CASLEO) in San Juan, Argentina (S31.8, W69.3; Rc = 9.659.65 GV). This instrument was developed at the Lebedev Physical Institute (LPI) in Russia as part of an international collaboration between the LPI, Brazil’s Mackenzie Center for Radioastronomy and Astrophysics (CRAAM), and the CASLEO. This work presents the results from analyzing variations in cosmic ray intensity recorded by the CARPET facility during the solar proton event of March 7, 2011. Also used in our analysis were the experimental data obtained by the GOES, FERMI, and ISS spacecraft during this solar event.

Solar and atmospheric influences in the cosmic ray intensity

Cosmic ray intensity at Earth changes with time and presents variations associated with the 11yr solar cycle, with interplanetary coronal mass ejections (ICME) arriving on the Earth’s magnetosphere, and with energetic particles produced during large solar flares. Studies also show that the cosmic rays can be related with atmospheric phenomena. Since cosmic rays are the main source of ionization between ~4 and ~60 km, they may influence climate phenomena as global cloud coverage and rain precipitation rate. Meteorological and atmospheric processes, such as changes in the ambient pressure and temperature, rain precipitation and variations of the atmospheric electric field can affect the cosmic ray counts observed by ground based detectors. In this work we present the results obtained with the CARPET charged particle detector installed at Astronomical Complex El Leoncito (CASLEO) in San Juan Argentina, since April 2006. We show and discuss the long term modulation of the cosmic ray flux associated with solar phenomena, like the 11-yr solar cycle and seasonal variations that can be related to changes in the atmospheric temperature. We also correct cosmic ray data for the barometric effect in order to discuss short time increases of the cosmic ray intensity in association to rain precipitation and changes in the atmospheric electric field.