A sensitive geomagnetic activity index for space weather operation

Du, Dan; Xu, Weihua; Zhao, Ming-Xian; Chen, B.; Lu, J. Y.; Yang, Guanglin

doi:10.1029/2010sw000609

Cited by 9 publications

(4 citation statements)

References 15 publications

(15 reference statements)

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“…The Dst index is a well-known geomagnetic index for describing the symmetric equatorial ring current. The Dst index is calculated on a one-hour basis using data from four geomagnetic observatories located at middle to low latitudes (Du et al, 2010). Thus, IMF-Bz indicates the variation on a geomagnetically disturbed event, whereas the Dst index relates to its strength and occurrence.…”

Section: Methodsmentioning

confidence: 99%

Singularity Detection on Forbush Decrease at High Latitude Stations During Geomagnetic Disturbances

Mishra

Silwal

Baral

et al. 2021

Preprint

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We analyzed the behavior of Cosmic Ray (CR) intensity during geomagnetic events of different nature and strength, using ground-based CR measurements from the World Neutron Monitoring Stations Network. We took account of interplanetary triggers and the geo-effectiveness while choosing the events. Forbush Decrease (FD) was observed when the magnetic fields entangled in and around CME exerts a shielding effect on galactic cosmic radiation, causing a sudden reduction of count rate in the neutron monitors. The results revealed that the FD plunged between -4% and -20% in the chosen events. The FD examined was abnormal and a multi-stage decrement in FD was observed during the event period. The reduction in Cosmic ray intensity was found to be inversely proportional to the cut - off rigidity at the specified neutron monitoring stations. Furthermore, we have also used the Discrete Wavelet Transform (DWT) technique to detect singularity on Forbush decrease at the stations described. The first three decomposition levels have proved sufficient to isolate singularity patterns associated with Forbush decrease in conjunction with events of different nature and intensity, ranging from intense geomagnetic storm to super intense geomagnetic storm to HILDCAA event. Also, we found that the cosmic ray flux was correlated with the IMF-Bz values and the SYM-H index during the process, as indicated by the cross-correlation technique. No noticeable lag has been found between the parameters discussed, which indicates a clear correlation between the IMF Bz and the SYM-H index and the FD.

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Section: Methodsmentioning

confidence: 99%

Singularity Detection on Forbush Decrease at High Latitude Stations During Geomagnetic Disturbances

Mishra

Silwal

Baral

et al. 2021

Preprint

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“…• Figures S1-S5, Captions for Tables S6-S9 • Figure S1 • Figure S2 • Figure S3 • Figure S4 • Figure S5 • Table S6 • Table S7 • Table S8 • Table S9 more precisely [Du et al, 2010]. The real-time Rice neural network models, where the Kp indices are not taken as inputs, take real-time inputs measured by the Advanced Composition Explorer (ACE) [Stone et al, 1998] to predict the short-term Kp index, and show better performance in verifying forecasts than the Wing Kp model [Bala et al, 2009;Bala and Reiff, 2012;Bala and Reiff, 2014].…”

Section: 1002/2015sw001251mentioning

confidence: 99%

“…Both are based on a neural network algorithm. The Du Kp model uses the real‐time observations of ground‐based magnetometers to produce the nowcast products of the Kp index, which depend on the geomagnetic latitude of the observatories, and can reflect the geomagnetic activity more precisely [ Du et al ., ]. The real‐time Rice neural network models, where the Kp indices are not taken as inputs, take real‐time inputs measured by the Advanced Composition Explorer (ACE) [ Stone et al ., ] to predict the short‐term Kp index, and show better performance in verifying forecasts than the Wing Kp model [ Bala et al ., ; Bala and Reiff , ; Bala and Reiff , ].…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis and verification of 3‐hourly geomagnetic activity probability predictions

et al. 2015

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The Space Environment Prediction Center (SEPC) has classified geomagnetic activity into four levels: quiet to unsettled (Kp < 4), active (Kp = 4), minor to moderate storm (Kp = 5 or 6), and major to severe storm (Kp > 6). The 3‐hourly Kp index prediction product provided by the SEPC is updated half hourly. In this study, the statistical conditional forecast models for the 3‐hourly geomagnetic activity level were developed based on 10 years of data and applied to more than 3 years of data, using the previous Kp index, interplanetary magnetic field, and solar wind parameters measured by the Advanced Composition Explorer as conditional parameters. The quality of the forecast models was measured and compared against verifications of accuracy, reliability, discrimination capability, and skill of predicting all geomagnetic activity levels, especially the probability of reaching the storm level given a previous “calm” (nonstorm level) or “storm” (storm level) condition. It was found that the conditional models that used the previous Kp index, the peak value of BtV (the product of the total interplanetary magnetic field and speed), the average value of Bz (the southerly component of the interplanetary magnetic field), and BzV (the product of the southerly component of the interplanetary magnetic field and speed) over the last 6 h as conditional parameters provide a relative operating characteristic area of 0.64 and can be an appropriate predictor for the probability forecast of geomagnetic activity level.

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“…We must also notice that our atmospheric model uses daily averages for the Solar activity parameters F 10.7 and A p . Although the solar radio flux varies according to the Solar cycles and it is relatively stable throughout the day, the geomagnetic index, A p , may show variations around ±5, specially in the case of Solar storms [21,41]. This corresponds to an uncertainty in the thermospheric density given by:…”

Section: Introductionmentioning

confidence: 99%

Kinematics effects of atmospheric friction in spacecraft flybys

Acedo¹

2017

Advances in Space Research

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Gravity assist manoeuvres are one of the most succesful techniques in astrodynamics. In these trajectories the spacecraft comes very close to the surface of the Earth, or other Solar system planets or moons, and, as a consequence, it experiences the effect of atmospheric friction by the outer layers of the Earth's atmosphere or ionosphere. In this paper we analyze a standard atmospheric model to estimate the density profile during the two Galileo flybys, the NEAR and the Juno flyby. We show that, even allowing for a margin of uncertainty in the spacecraft cross-section and the drag coefficient, the observed -8 mm/sec anomalous velocity decrease during the second Galileo flyby of December, 8th, 1992 cannot be attributed only to atmospheric friction. On the other hand, for perigees on the border between the termosphere and the exosphere the friction only accounts for a fraction of a millimeter per second in the final asymptotic velocity.Comment: 5 figures, 3 table

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A sensitive geomagnetic activity index for space weather operation

Cited by 9 publications

References 15 publications

Singularity Detection on Forbush Decrease at High Latitude Stations During Geomagnetic Disturbances

Singularity Detection on Forbush Decrease at High Latitude Stations During Geomagnetic Disturbances

Statistical analysis and verification of 3‐hourly geomagnetic activity probability predictions

Kinematics effects of atmospheric friction in spacecraft flybys

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