Effects of the April 1994 Forbush events on the fluxes of the energetic charged particles measured on board CORONAS-I: their connection with conditions in the interplanetary medium

Kuznetsov, S. N.; Myagkova, I. N.; Ryumin, S. P.; Kudela, K.; Buchik, R.; Mavromichalaki, H.

doi:10.1016/s1364-6826(02)00010-x

Cited by 6 publications

(6 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The most severe event in the 41 year period is the 18 day interval starting on 2 April 1994. This event starts with moderate storm, with S Y M ‐ H driven to just below −130 nT during the magnetosphere's passage through a high‐velocity solar wind stream which ended on 16 April 1994 (Kuznetsov et al, ). The high‐speed stream emanating from a large coronal hole caused the magnetosphere to be disturbed for a prolonged period, resulting in elevated planetary K index for about 15 days (Borovsky et al, ).…”

Section: Discussionmentioning

confidence: 99%

Extreme Value Analysis of Induced Geoelectric Field in South Africa

Lotz

Danskin

2017

Space Weather

View full text Add to dashboard Cite

Extreme geomagnetic disturbances occur rarely but can have great impact on technological systems such as power supply networks. Long‐term planning for extreme events requires the estimation of event impact for occurrence periods greater than the length of observed data. With this in mind an analysis of extreme geomagnetic events observed in South Africa (middle geomagnetic latitude) is performed over four solar cycles (1974–2015). An algorithm to identify active periods with minimum SYM‐H ≤−100 nT is demonstrated. The sum of induced electric field over the course of each event is used to characterize the severity of each active period. It is found that the severity index (accumulated electric field magnitude ΣE) shares a highly linear relationship with accumulated SYM‐H over each event. The index ΣE is lognormal distributed, with tail deviating greater than lognormal, confirming heavy‐tailed occurrence. A general Pareto distribution is fitted to the tail of the distribution and extrapolated to calculate the return levels of extreme events. Return levels of once in 100 and once in 200 year events are estimated to be 9.4 × 104 mV/km min and 1.09 × 105 mV/km min, respectively. The top three events, in ascending order of severity, are the March 1989 storm, the events of late October 2003, and the April 1994 event—a long interval of coronal‐hole driven disturbances, bookended by two intense geomagnetic storms.

show abstract

Section: Discussionmentioning

confidence: 99%

Extreme Value Analysis of Induced Geoelectric Field in South Africa

Lotz

Danskin

2017

Space Weather

View full text Add to dashboard Cite

show abstract

“…Its high count rate allows to study variations of low-energy cosmic rays at different latitudes separately for each orbit, providing thus nearly momentary latitudinal survey. Kuznetsov et al [35] reported that, while being in agreement at high latitudes, SONG data did not correspond to the data of middle-latitude neutron monitors (Climax and LARC, both have P C ≈ 3 GV) during a strong geomagnetic disturbance and the related ) and for a low orbit (500 km, corresponding to CORONAS I). We found that a large Dst depression (−300 nT) may cause a very strong depression of the effective vertical cut-off rigidity from 3 GV down to 1.71 GV and to 0.92 GV for the altitudes of 20 km and 500 km, respectively.…”

Section: The Effect Of External Field At Middle Latitudesmentioning

confidence: 93%

“…Fig. 3 of [35]) during geomagnetic disturbance and Forbush decrease) would be of interest from the point of view of penumbra expectations and approaches of the trajectory calculations.…”

Section: The Effect Of External Field At Middle Latitudesmentioning

confidence: 99%

On Magnetospheric Transmissivity of Cosmic Rays

Kudela

Usoskin

2004

Czechoslovak Journal of Physics

Self Cite

View full text Add to dashboard Cite

Results of computations of cosmic-ray trajectories in the model magnetic field obtained for a high-latitude neutron-monitor station (Oulu) and a middle-latitude one (Lomnický Stít) are summarized. The method is slightly different from previous computations by controlling the smoothness of the trajectory. At the lowest rigidity edge of allowed trajectories for Oulu (above the atmospheric cut-off), the external field and the addition of Dst shows variations of the asymptotic directions with the level of geomagnetic activity and with local time of observations. The transmissivity function introduced here, accounting for variability of the magnetic field with changing Kp and with local time, may be used as a reference for description of the average magnetospheric transparency at middle latitudes and it is probably better approximation than IGRF only. There are indications of appearance of windows of allowed trajectories at very low rigidities in the middle latitudes at 500 km (altitude of, e.g., CORONAS satellites or ISS) during the geomagnetic disturbance which is not the case for trajectories computed from the ground. : 96.40.Kk, 95.85.Ry PACS

show abstract

“…range of (50-90)MeV, is used in our study. However, at an earlier experiment on CORONAS-I we showed that the decreases of galactic cosmic rays could have been observed by means of a similar instrument at the channel with even higher energies [26]. Figure 3 shows the time evolution of proton measurements by MKL instrument.…”

Section: Transmissivity During Solar Flare Events: Coronas-f Observatmentioning

confidence: 86%

Changes of geomagnetic transmissivity in the disturbed magnetosphere: ground-based and CORONAS-F observations

et al. 2006

Self Cite

View full text Add to dashboard Cite

We report increases of cosmic-ray intensity at low L shells, on the ground as well as on the altitude of 500 km, during the selected intervals when magnetosphere was strongly disturbed. The geomagnetic transmissivity for cosmic ray vertical access has been computed for four events, using two geomagnetic field models. The first event, namely, dated November 20-22, 2003, led to an increase of galactic cosmic-ray intensity due to the improvement of magnetospheric transmissivity at neutron monitors with high nominal cut-off rigidity. Other two events with high-energy solar proton emissions, namely, dated October 28 and November 2, 2003, caused different responses at middle latitudes. The first one followed by the strong geomagnetic disturbance led to the shift of the penetration boundary of protons, having (50-90) MeV at CORONAS-F satellite to L < 3, coinciding approximately with the cut-off reduction expected by Dst depression, while the other one, without remarkable Dst decrease, did not shift the outer boundary of penetration below L ~ 4. And the fourth of the events, on November 8, 2004, with strong geomagnetic disturbance, yielded a complicated structure of cosmic-ray time profiles: superimposed on the cosmic-ray decrease, viewed by neutron monitors and by CORONAS-F at high latitude; an increase of intensity at middle latitudes both on the ground and on the altitude of 500 km has been observed during the Dst depression.PACS: 94.20.wq

show abstract

Effects of the April 1994 Forbush events on the fluxes of the energetic charged particles measured on board CORONAS-I: their connection with conditions in the interplanetary medium

Cited by 6 publications

References 5 publications

Extreme Value Analysis of Induced Geoelectric Field in South Africa

Extreme Value Analysis of Induced Geoelectric Field in South Africa

On Magnetospheric Transmissivity of Cosmic Rays

Changes of geomagnetic transmissivity in the disturbed magnetosphere: ground-based and CORONAS-F observations

Contact Info

Product

Resources

About