Regular Article

Influence of short-term solar disturbances on the fair weather conduction current

¹ Department of Geophysical, Atmospheric and Planetary Sciences, Tel-Aviv University, Israel
² Department of Life and Natural Sciences, Open University of Israel, Israel
³ Institute of Geophysics and Pleasantry Physics, Scripps Institute of Oceanography, San-Diego, USA
⁴ Department of Meteorology, University of Reading, UK
⁵ Interdisciplinary Center Herzliya (IDC), Israel

^* Corresponding author: yoavya@openu.ac.il

Received: 15 September 2013
Accepted: 6 August 2014

Abstract

The fair weather atmospheric electrical current (J_z) couples the ionosphere to the lower atmosphere and thus provides a route by which changes in solar activity can modify processes in the lower troposphere. This paper examines the temporal variations and spectral characteristics of continuous measurements of J_z conducted at the Wise Observatory in Mitzpe-Ramon, Israel (30°35′ N, 34°45′ E), during two large CMEs, and during periods of increased solar wind density.

Evidence is presented for the effects of geomagnetic storms and sub-storms on low latitude J_z during two coronal mass ejections (CMEs), on 24–25th October 2011 and 7–8th March 2012, when the variability in J_z increased by an order of magnitude compared to normal fair weather conditions. The dynamic spectrum of the increased J_z fluctuations exhibit peaks in the Pc5 frequency range. Similar low frequency characteristics occur during periods of enhanced solar wind proton density. During the October 2011 event, the periods of increased fluctuations in J_z lasted for 7 h and coincided with fluctuations of the inter-planetary magnetic field (IMF) detected by the ACE satellite. We suggest downward mapping of ionospheric electric fields as a possible mechanism for the increased fluctuations.