|
Wavelet Spectral Analysis of the ENIGMA Magnetometer Array Time Series and Solar Wind Conditions around the Strongest Magnetic Storms of Solar Cycle 24 |
|
Boutsi, Z. (1,2), Balasis, G. (1) |
|
(1) Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, Greece, (2) Section of Astrophysics, Astronomy and Mechanics, Department of Physics, National and Kapodistrian University of Athens, Greece |
|
Magnetic storms are undoubtedly among the most important phenomena in space physics and also a central subject of space weather. The HellENIc GeoMagnetic Array (ENIGMA) is a network of 4 ground-based magnetometer stations in the areas of Thessaly, Central Greece, Peloponnese and Crete in Greece that provides measurements for the study of geomagnetic pulsations, resulting from the solar wind - magnetosphere coupling. ENIGMA magnetometer array enables effective remote sensing of geospace dynamics and the study of space weather effects on the ground (i.e. Geomagnetically Induced Currents - GIC). ENIGMA contributes data to SuperMAG, a worldwide collaboration of organizations and national agencies that currently operate approximately 500 ground-based magnetometers. Here we study the Earth’s magnetic field time variations measured by ENIGMA for 2015, when the three strongest magnetic storms of solar cycle 24 occurred in March, June and December, along with the corresponding solar wind parameters and geomagnetic activity indices. We apply spectral analysis techniques based on wavelet transforms and calculate the Hurst exponent of these time series. Our results show the existence of two different patterns: (i) a pattern associated with the intense magnetic storms, which is characterized by higher Hurst values; (ii) a pattern associated with the quiet-time magnetosphere, which is characterized by lower Hurst values. |
|
Applications |
|
oral |
|
|