Open AccessCorrelating the interplanetary factors to distinguish extreme and major geomagnetic storms
Author(s) -
Balachandran Ragini,
Chen LiJen,
Wang Shan,
Fok MeiChing
Publication year - 2021
Publication title -
earth and planetary physics
Language(s) - English
Resource type - Journals
ISSN - 2096-3955
DOI - 10.26464/epp2021015
Subject(s) - interplanetary spaceflight , geomagnetic storm , earth's magnetic field , storm , geology , solar wind , geophysics , astrobiology , meteorology , physics , nuclear physics , plasma , magnetic field , quantum mechanics
We investigate the correlation between Disturbance Storm Time ( Dst ) characteristics and solar wind conditions for the main phase of geomagnetic storms, seeking possible factors that distinguish extreme storms (minimum Dst <−250 nT) and major storms (minimum Dst <−100 nT). In our analysis of 170 storms, there is a marked correlation between the average rate of change of Dst during a storm's main phase (Δ Dst /Δ t ) and the storm's minimum Dst , indicating a faster Δ Dst /Δ t as storm intensity increases. Extreme events add a new regime to Δ Dst /Δ t , the hourly time derivative of Dst (d Dst /d t ), and sustained periods of large amplitudes for southward interplanetary magnetic field B z and solar wind convection electric field E y . We find that E y is a less efficient driver of d Dst /d t for extreme storms compared to major storms, even after incorporating the effects of solar wind pressure and ring current decay. When minimum Dst is correlated with minimum B z , we observe a similar divergence, with extreme storms tending to have more negative Dst than the trend predicted on the basis of major storms. Our results enable further improvements in existing models for storm predictions, including extreme events, based on interplanetary measurements.