Solar filament impact on 21 January 2005: Geospace consequences

Abstract

On 21 January 2005, a moderate magnetic storm produced a number of anomalous features, some seen more typically during superstorms. The aim of this study is to establish the differences in the space environment from what we expect (and normally observe) for a storm of this intensity, which make it behave in some ways like a superstorm. The storm was driven by one of the fastest interplanetary coronal mass ejections in solar cycle 23, containing a piece of the dense erupting solar filament material. The momentum of the massive solar filament caused it to push its way through the flux rope as the interplanetary coronal mass ejection decelerated moving toward 1 AU creating the appearance of an eroded flux rope (see companion paper by Manchester et al. (2014)) and, in this case, limiting the intensity of the resulting geomagnetic storm. On impact, the solar filament further disrupted the partial ring current shielding in existence at the time, creating a brief superfountain in the equatorial ionosphere-an unusual occurrence for a moderate storm. Within 1 h after impact, a cold dense plasma sheet (CDPS) formed out of the filament material. As the interplanetary magnetic field (IMF) rotated from obliquely to more purely northward, the magnetotail transformed from an open to a closed configuration and the CDPS evolved from warmer to cooler temperatures. Plasma sheet densities reached tens per cubic centimeter along the flanks-high enough to inflate the magnetotail in the simulation under northward IMF conditions despite the cool temperatures. Observational evidence for this stretching was provided by a corresponding expansion and intensification of both the auroral oval and ring current precipitation zones linked to magnetotail stretching by field line curvature scattering. Strong Joule heating in the cusps, a by-product of the CDPS formation process, contributed to an equatorward neutral wind surge that reached low latitudes within 1-2 h and intensified the equatorial ionization anomaly. Understanding the geospace consequences of extremes in density and pressure is important because some of the largest and most damaging space weather events ever observed contained similar intervals of dense solar material.

Satellite observations of energy‐banded ions during large geomagnetic storms: Event studies, statistics, and comparisons to source models

“…The banded ions are observed in all of the large storms encountered by the FAST satellite, but they are also observed in some more moderate (minimum Dst ~ −100 nT) storms. In particular, the 21 January 2005 storm had a minimum Dst of only −105 nT, but featured several phenomena typically associated with larger storms [ Kozyra et al ., , ], including warm energy‐banded ions similar to those reported herein, with multiple bands at the same energies observed in different components (H + and He + or H + and O + ). We are preparing additional studies of this fascinating storm, including the finding that the observed bands were consistent with time‐of‐flight mechanisms from a localized source if we suppose a superposition of multiple bands formed by protons bouncing between mirror points combined with the time‐of‐flight separation of heavier ions (He + and O + ) arriving directly from the source.…”

“…Note that there are other band-like features that have been observed and modeled, including the ion "gaps" [see, e.g., Kovrazhkin et al, 1999], "wedge"-type dispersion [Ebihara et al, 2001], and velocity-dispersed ions in the plasma sheet boundary layer [Ashour-Abdalla et al, 1992, 2005Bosqued et al, 1993]. During superstorms, ion distributions resembling wedge-like ions frequently appear as an important component at the lowest latitudes overlapping with the banded ions.…”

Solar wind driving of ionosphere‐thermosphere responses in three storms near St. Patrick's Day in 2012, 2013, and 2015

“…The CME dark region is identified as a magnetic cloud at 1 AU [ Burlaga et al, ; Klein and Burlaga , ]. Filaments at 1 AU were first discovered by Burlaga et al [] and recently discussed in terms of geoeffectiveness by Kozyra et al [].…”

Searching for Carrington-like events and their signatures and triggers

“…The higher temporal resolution of SYM-H index does not prevent from missing the negative disturbance of the first hour after the SC, as it is the result of the average. Kozyra et al (2014) reviewed the unusual geospace consequences of the event on 21 January 2005. Although their study is mainly focused on the interval after the solar filament material arrival (~18:45 UT), it also includes interesting information regarding the first hours after the SC.…”