Super storms

Abstract

Abstract. "Super storms" are defined to be the largest 2% of geomagnetic storms from 1932 through 1995, selected using ground-based magnetic indices. These storms are significant not only because they are prolonged periods of extremely high magnetic activity but also because data taken during super storms in the space era show other anomalous features, such as abnormally high energy input to the auroral regions from precipitating particles, and/or the creation of additional, trapped radiation belts in the inner magnetosphere. Super storms are most likely to occur on the downslope from solar maximum and near the equinoxes. One half of the super storms have multiple SSCs that reactivate magnetospheric currents and prolong magnetic activity. AE "spikes" occur during some of the super storms. The relationship between super storms and the locations of trapped radiation populations is briefly examined. The auroral energy input to the inner magnetosphere during recent super storms is calculated and presented. Even though quantitative criteria can be (by and large) arbitrary, they have been found to be useful. Magnetic indices have also been used to characterize "larger" and "largest" storms.The purpose of this paper is to identify the top 2% of magnetic storms since 1932 (our "super storms"), using the available ap, Kp, Dst, andAE data. We examine these storms in some detail, focusing on when they occur, similarities in their morphology, long-term changes to trapped particle populations, and auroral energy input levels. Selection of StormsThe magnetic indices we used in this study cover the period from 1932 through 1995. Quantitative selection criteria were developed for four magnetic indices (Kp, ap, Dst, and AE) and used to select the largest storms for each index. The process that led to these criteria was evolutionary in nature, with the criteria and values used being adjusted slightly at each step. Combinations of various criteria were used to assure that the super storms had both large magnitudes and long durations.Initially, we considered using only the magnitude of magnetic activity to select the largest storms. However, for the small number of storms we wished to select this proved impractical, particularly for Kp and ap (too many storms contain the maximum possible values for Kp and ap). It also resulted in the occasional selection of brief, but very intense periods of magnetic disturbance, periods that did not affect the particle populations as strongly as longer lasting storms. Therefore the largest storms for each index were selected by requiring a combination of disturbance magnitude and duration of the disturbance. After the largest storms for each index were selected the results were compared. Some storms were selected 14,189

The strong Pc5 geomagnetic pulsations in the initial phase of the great magnetic storm of March 24, 1991

“…An exceptional strong magnetic storm happened on March 24, 1991. According to Bell et al (1997), it belongs to the "super storm" class for it is characterized by an exceptionally large geomagnetic sudden commencement (SSC) occurring at 03.41 UT (Araki et al, 1997), Dst = -298 nT (24 UT) and AE as large as ~4000 nT at 04-05 UT. The Dst index decreased in the 04-10 UT interval from +63 nT to -98 nT and increased in the 10-14 UT interval from -98 nT to -57 nT.…”

Energy balance during intense and super-intense magnetic storms using an Akasofu ε parameter corrected by the solar wind dynamic pressure

“…The presence of high values of southward IMF-Bz (B S ) and solar wind speed (u), which result in an increased interplanetary electric field duskward component E y ¼ uB S ; is responsible for the magnetospheric energization. One of the mechanisms for creating even higher field strengths is the IMF compression, especially on the sheath regions behind the shock or the ejecta clouds (Tsurutani et al, 1999(Tsurutani et al, , 1992Bell et al, 1997;Gonzalez et al, 2002).…”

The Radiation Environment Impacting DSX Orbit Options

“…The lowest doses are accumulated by the higher inclination Medium Earth orbits (5-8) which intersect the middle belt at higher latitudes and, with a more distant perigee, spend less time in the inner and outer belt regions than do the inner belt orbits. Long-lived middle belts are a relatively rare occurrence, estimated to happen roughly once per solar cycle (Bell, et al, 1997). However, given the huge increase in dose observed by some MEO orbits (e.g.…”