Atmospheric electric field anomalies associated with solar flare/coronal mass ejection events and solar energetic charged particle "Ground Level Events"

Abstract

Abstract. We discuss the fair weather atmospheric electric field signatures of three major solar energetic charged particle events which occurred in on 15 April 2001, 18 April and 4 November, and their causative solar flares/coronal mass ejections (SF/CMEs). Only the 15 April 2001 shows clear evidence for Ez variation associated to SF/CME events and the other two events may support this hypothesis as well although for them the meteorological data were not available. All three events seem to be associated with relativistic solar protons (i.e. protons with energies >450 MeV) of the Ground Level Event (GLE) type. The study presents data on variations of the vertical component of the atmospheric electric field (Ez) measured at the auroral station Apatity (geomagnetic latitude: 63.8°, the polar cap station Vostok (geomagnetic latitude: −89.3°) and the middle latitude stations Voyeikovo (geomagnetic latitude: 56.1°) and Nagycenk (geomagnetic latitude: 47.2°). A significant disturbance in the atmospheric electric field is sometimes observed close to the time of the causative solar flare; the beginning of the electric field perturbation at Apatity is detected one or two hours before the flare onset and the GLE onset. Atmospheric electric field records at Vostok and Voyeikovo show a similar disturbance at the same time for the 15 April 2001 event. Some mechanisms responsible for the electric field perturbations are considered.

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

“…A very large (~5000 km) ionospheric disturbance of 50 mV m À1 would result in a surface electric field change of this scale (similar magnitude to electric field measured by Kasatkina et al 2009) which could induce currents of similar magnitudes to those observed in the Mitzpe Ramon J z measurements. It is likely that such large ionospheric disturbances can arise in the hours following a CME, however, effects are generally expected to be confined to high latitude regions.…”

“…The fluctuations are thought to be associated with variations in the ionization rate above the UK (measured simultaneously from a balloon, but not detected by surface neutron monitors), which perturb the electric field in the lower troposphere sufficiently to induce displacement currents at the surface. Furthermore, electric field changes of 1000 V m À1 during a 10 min period were reported by Kasatkina et al (2009) at high latitudes (63.3 N) during three ground level events in 2001. The variations spread over a large area and reached down to mid-latitudes (50 V m À1 changes in E z at 47.2 N).…”

“…They attributed the increased fluctuations to displacement current effects. Most evidence for solar effects on atmospheric electricity has come from high latitude regions; however, Kasatkina et al (2009) …”

Network of observations on the atmospheric electrical parameters during geomagnetic storm on 5 April 2010

“…Particularly, the departure of the atmospheric electric field at middle latitudes due to substorm disturbances was examined by Kleimenova et al [2011] and the similar study had been carried out for large geo-effective storms [Sheftel et al, 1992[Sheftel et al, , 1994. In recent studies, Kasatkina et al [2009] analyzed the solar flare/ground level event's influence on the atmospheric electric field measured from the middle-to high-latitude stations and reported that the changes on the PG are subjected to many factors such as the relative Sun-Earth position, conditions in interplanetary space, and state of the ionosphere and of the atmosphere at middle and high latitudes. Moreover, the magnitude of geomagnetic substorms influencing the atmospheric electrical parameters may vary at different time periods when analyzing multiple stations becomes quite cumbersome.…”

Impact of Coronal Mass Ejection on different characteristic parameters of lower thermospheric region

“…This process generates and releases trapped particles and electromagnetic radiation in the form of solar X-rays and γ-ray bursts [10][11][12][13][14] . This intense radiation is responsible for ionizing the constituent particles of the ionosphere.…”