Geomagnetic transmission of solar energetic protons during the geomagnetic disturbances of October 1989

Boberg, P. R.; Tylka, A. J.; Adams, J. H.; Flückiger, E. O.; Kobel, E.

doi:10.1029/95gl00948

Cited by 38 publications

(31 citation statements)

References 10 publications

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“…The Tsyganenko (1989) magnetospheric field model describes the magnetospheric field topologies for Kp" magnetic indices from 0 to 5. The Boberg et al, (1995) extension was used to describe the magnetospheric fields for magnetic activity levels exceeding Kp values of 5. For convenience we have labeled these as Kp 6 through 10 in Dst^ increments of-100 nT.…”

Section: Introductionmentioning

confidence: 99%

The space-developed dynamic vertical cutoff rigidity model and its applicability to aircraft radiation dose

Smart

Shea

2003

Advances in Space Research

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Section: Introductionmentioning

confidence: 99%

The space-developed dynamic vertical cutoff rigidity model and its applicability to aircraft radiation dose

Smart

Shea

2003

Advances in Space Research

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“…The CL model of Smart et al (1999) used in DRAP (Sauer & Wilkinson 2008) was based on particle ray tracing through a Tsyganenko (1989) model of the magnetosphere parameterised by the K p index for K p = 0 to 5, and extended by Boberg et al (1995) for D st index values from 0 to À500 nT. Dmitriev et al (2010) determined the CL from proton flux measurements on the NASA Polar Orbiting Operational Environment Satellites (POES) fitting ellipses to the observed CL, parameterised by magnetic local time (MLT), the dipole tilt angle, and geomagnetic indices D st , K p and (in the case of energetic electrons) the AE index.…”

Section: Rigidity Cut-off Latitude Modelsmentioning

confidence: 99%

Assimilation of real-time riometer measurements into models of 30 MHz polar cap absorption

Rogers

Honary

2015

J. Space Weather Space Clim.

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Space weather events may adversely affect high frequency (HF) radio propagation, hence the ability to provide nowcasting and forecasting of HF radio absorption is key for industries that rely on HF communications. This paper presents methods of assimilating 30 MHz radio absorption measurements into two types of ionospheric polar cap absorption (PCA) model to improve their performance as nowcasting tools. Type 1 models calculate absorption as m times the square root of the flux of solar protons above an energy threshold, E t . Measurements from 14 riometers during 94 solar proton events (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) are assimilated by optimising the day and night values of m by linear regression. Further non-linear optimisations are demonstrated in which parameters such as E t are also optimised and additional terms characterise local time and seasonal variations. These optimisations reduce RMS errors by up to 36%. Type 2 models incorporate altitude profiles of electron and neutral densities and electron temperatures. Here the scale height of the effective recombination coefficient profile in the D-region is optimised by regression. Furthermore, two published models of the rigidity cut-off latitude (CL) are assessed by comparison with riometer measurements. A small improvement in performance is observed by introducing a 3-h lag in the geomagnetic index K p in the CL models. Assimilating data from a single riometer in the polar cap reduces RMS errors below 1 dB with less than 0.2 dB bias. However, many highlatitude riometers now provide absorption measurements in near-real time and we demonstrate how these data may be assimilated by fitting a low-order spherical harmonic function to both the measurements and a PCA model with optimised parameters.

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“…We describe effects of the external-field model [11] and its extension with including Dst, according to [12], which is found to be relevant for neutron monitor measurements at high (Oulu) and a middle (LomnickýŠtít) latitude stations as well as for low-altitude satellites. We also test the stability of the trajectory and consequent cut-off computations vs. uncertainties of the magnetic-field models.…”

Section: Introductionmentioning

confidence: 99%

On Magnetospheric Transmissivity of Cosmic Rays

Kudela

Usoskin

2004

Czechoslovak Journal of Physics

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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

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Geomagnetic transmission of solar energetic protons during the geomagnetic disturbances of October 1989

Cited by 38 publications

References 10 publications

The space-developed dynamic vertical cutoff rigidity model and its applicability to aircraft radiation dose

The space-developed dynamic vertical cutoff rigidity model and its applicability to aircraft radiation dose

Assimilation of real-time riometer measurements into models of 30 MHz polar cap absorption

On Magnetospheric Transmissivity of Cosmic Rays

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