Magnetospheric effects in cosmic rays during the unique magnetic storm on November 2003

Abstract

[1] Cosmic ray variations due to changes in the magnetosphere are evaluated for severe magnetic storm on 20 November 2003 using data from the worldwide neutron monitor network and the global survey method. From these results the changes in the planetary distribution of magnetic cutoff rigidities during this disturbed period are obtained in dependence of latitude. A correlation between Dst index and cutoff rigidity variations was defined for each cosmic ray station. The maximum changes in cutoff rigidities occurred while Dst index was around À472 nT. Geomagnetic effect in cosmic ray intensity reached at some stations 6-8%, and it seems to be the greatest one over the history of neutron monitor observations. The latitudinal distribution shows a maximum changes at geomagnetic cutoff rigidities around 7-8 GV. This corresponds to unusually low latitudes for maximal effect. Cutoff rigidity variations were also calculated utilizing the last model of Tsyganenko for a disturbed magnetosphere (T01S). A comparison between experimental and modeling results revealed a big discrepancy at cutoff rigidities less than 6 GV. The results on the geomagnetic effect in cosmic rays can be used for validating magnetospheric field models during very severe storms.

Anomalous behavior of cutoff rigidity variation in the region of the Mexico station during a magnetic superstorm on 20 November 2003

“…The event of 20 November 2003, observed in CR, was preceded by a series of solar flares of class M, which occurred on 17-18 November 2003, that initiated the strongest magnetic storm in a series of magnetic storms throughout this period (Belov et al, 2005;Vashenyuk et al, 2005;Dvornikov et al, 2003). After the arrival of a shock wave, the Earth entered an extended magnetic cloud, where the intensity of the interplanetary magnetic field (IMF) was as large as 60 nT, with the B z IMF being −45 nT.…”

“…According to the NOAA classification, this magnetic storm belongs to the Correspondence to: V. V. Pchelkin (pchelkin@pgi.kolasc.net.ru) class G4-G5 (an extremely strong one), as indicated by the K p index and to the class r (a giant one), as classified by D st . The auroras were observed in the south of Europe and at mid-latitudes, indicating a strong equatorward shift of the auroral oval (Belov et al, 2005). Belov et al (2005) applied the global survey method to the data of the worldwide neutron monitor network and obtained the latitudinal distributions of changes in magnetic cutoff rigidities at different stages of the storm considered.…”

“…The auroras were observed in the south of Europe and at mid-latitudes, indicating a strong equatorward shift of the auroral oval (Belov et al, 2005). Belov et al (2005) applied the global survey method to the data of the worldwide neutron monitor network and obtained the latitudinal distributions of changes in magnetic cutoff rigidities at different stages of the storm considered. Hourly data from 39 neutron monitors of the worldwide network have been employed in the detailed analysis.…”

An Early Diagnostics of the Geoeffectiveness of Solar Eruptions from Photospheric Magnetic Flux Observations: The Transition from SOHO to SDO

“…The onset transit time, ∆T o , is defined as an arrival time of the corresponding interplanetary disturbance (shock wave) at Earth indicated by the geomagnetic storm sudden commencement (SSC) (http://www.obsebre.es/en/rapid). Following Article I, the FD maximum magnitude is adopted; this magnitude corresponds to a cosmic ray rigidity of 10 GV evaluated from data of the world network of neutron monitors using the global survey method (Krymskii et al, 1981;Belov et al, 2005). Additionally, the eighteenth and nineteenth columns of Table 3 list the hourly strength of the total interplanetary magnetic field near the Earth, Bt, and its Bz component according to the Operating Missions as a Node on the Internet (OMNI) data (ftp://spdf.gsfc.nasa.gov/pub/data/omni/low res omni/).…”

Procedure to emend neutron monitor data that are affected by snow accumulations on and around the detector housing

“…However, remote reference stations have to be used carefully. The right way would be to calculate the variations expected at the given point by the global survey method [Belov et al, 2005] and to use this result as the reference data.…”