Sciences and Exploration Directorate

Shrikanth G Kanekal

(RESEARCH AST, FIELDS AND PARTICLES)

 shrikanth.g.kanekal@nasa.gov

 301.286.6396

Org Code: 672

NASA/GSFC
Mail Code: 672
Greenbelt, MD 20771

Employer: NASA

Brief Bio



 Dr. Kanekal's research interests include energization and loss processes of relativistic electrons in the Earth's magnetosphere, solar energetic particles, Jovian electrons, magnetospheric energetic particle boundary dynamics, space Instrumentation, and space weather. He was involved in several NASA missions including the HERMES/Lunar Gateway, Van Allen Probes as well as two CubeSats, CeREs, and CusP. He is currently building the MERiT (Miniaturized Electron Proton Telescope), for the Lunar Gateway. 

On Van Allen Probes, he has been involved in the design and calibration of the REPT (Relativistic Electron Proton Telescope) instrument and made significant contributions to refining science objectives, instrument requirements, and REPT hardware. He was fully responsible for the GEANT4 simulation of REPT and developed software to simulate the detector geometry with high fidelity. He has also used GEANT4 simulations for optimization of event trigger types, estimation of backgrounds due to inner belt protons, GCRs, ultra-relativistic electrons and impact of magnetometer boom within field of regard. He has directed and participated in the REPT beam test calibration at UC Davis, Indiana cyclotron facility, Lawrence Berkeley Laboratories for protons and at the Idaho Electron accelerator facility for electrons.He has done extensive work in cross calibrating REPT with MagEIS (Magnetic Electron Ion Spectrometer) sensor. 

Dr. Kanekal's involvement in scientific analyses of energetic particle data obtained from SAMPEX since its launch in 1992 has been extensive. He has been fully responsible for writing the browse and level-2 data software and participated in calibrating the PET sensor onboard SAMPEX. He continues to carry on science analyses using SAMPEX data. He has been the PI of a NASA grant to make the SAMPEX data (2004 onwards) available to the public by expanding the SAMPEX data server. On the Polar mission, he has been extensively involved with the CEPPAD suite of instruments. He has used energetic electron and proton data from sensors onboard SAMPEX and Polar to study various physical phenomena in the Earth's radiation belts, such as electron energization and loss, trapping of solar protons, access of low energy cosmic rays and space weather. 

Dr. Kanekal's Ph.D. research involved precision measurements of the hadronic branching fractions tau->K* nu and tau->rho nu, which resulted in the first measurements of a fundamental constant of nature, the Cabbibo angle using τ lepton decays. His research included decay modes of charmed mesons, the ? lepton, the ϒ resonances, as well as detector simulation software. Dr. Kanekal has extensive experience in different types of particle detectors and associated detection techniques. As a postdoctoral fellow, he maintained the detector simulation package of the CUSB detector at CESR, the Cornell electron positron storage ring; at Fermilab, he was a member of the D0 team, where he carried out Geant modeling of D0, 

Education



Ph.D. Physics (High Energy, experimental) University of Kansas 1988 

B.E. Electrical Engineering University of Bangalore 1980 

Publications


Refereed

Spence, H. E., G. D. Reeves, D. N. Baker, et al. J. B. Blake, M. Bolton, S. Bourdarie, A. A. Chan, S. G. Claudepierre, J. H. Clemmons, J. P. Cravens, S. R. Elkington, J. F. Fennell, R. H. Friedel, H. O. Funsten, J. Goldstein, J. C. Green, A. Guthrie, M. G. Henderson, R. B. Horne, M. K. Hudson, J.-M. Jahn, V. K. Jordanova, S. G. Kanekal, B. W. Klatt, B. A. Larsen, X. Li, E. A. MacDonald, I. R. Mann, J. Niehof, T. P. OBrien, T. G. Onsager, D. Salvaggio, R. M. Skoug, S. S. Smith, L. L. Suther, M. F. Thomsen, and R. M. Thorne. 2013. Science Goals and Overview of the Radiation Belt Storm Probes(RBSP) Energetic Particle, Composition, and Thermal Plasma (ECT) Suite on NASA's Van Allen Probes Mission Space Science Reviews 179 311-336 [10.1007/s11214-013-0007-5]

Baker, D. N., S. G. Kanekal, V. C. Hoxie, et al. S. Batiste, M. Bolton, X. Li, S. R. Elkington, S. Monk, R. Reukauf, S. Steg, J. Westfall, C. Belting, B. Bolton, D. Braun, B. Cervelli, K. Hubbell, M. Kien, S. Knappmiller, S. Wade, B. Lamprecht, K. Stevens, J. Wallace, A. Yehle, H. E. Spence, and R. Friedel. 2013. The Relativistic Electron-Proton Telescope (REPT) Instrument on Board the Radiation Belt Storm Probes (RBSP) Spacecraft: Characterization of Earth's Radiation Belt High-Energy Particle Populations Space Science Reviews 179 337-381 [10.1007/s11214-012-9950-9]

Mauk, B. H., N. J. Fox, S. G. Kanekal, et al. R. L. Kessel, D. G. Sibeck, and A. Ukhorskiy. 2013. Science Objectives and Rationale for the Radiation Belt Storm Probes Mission Space Science Reviews 179 3-27 [10.1007/s11214-012-9908-y]

Thorne, R. M., W. Li, B. Ni, et al. Q. Ma, J. Bortnik, L. Chen, D. N. Baker, H. E. Spence, G. D. Reeves, M. G. Henderson, C. A. Kletzing, W. S. Kurth, G. B. Hospodarsky, J. B. Blake, J. F. Fennell, S. G. Claudepierre, and S. G. Kanekal. 2013. Rapid local acceleration of relativistic radiation-belt electrons by magnetospheric chorus Nature 504 411-414 [10.1038/nature12889]

Baker, D. N., and S. G. Kanekal. 2011. Studying changes of energetic particle properties in the Earth's radiation belts using the SAMPEX, POLAR, and Cluster missions AGU Fall Meeting Abstracts A8-

Mauk, B. H., N. J. Fox, D. G. Sibeck, S. G. Kanekal, and R. Kessel. 2011. Untangling complex processes within Earth's radiation belts with the Radiation Belt Storm Probes (RBSP) mission AGU Fall Meeting Abstracts 6-

Kanekal, S. G., D. N. Baker, J. F. Fennell, and B. Klecker. 2011. Relativistic electron losses by microbursts and their relationship to flux decay time scales AGU Fall Meeting Abstracts 4-

Fennell, J., S. G. Kanekal, and J. L. Roeder. 2010. Stormtime Energetic Electron Responses for L≤4 AGU Fall Meeting Abstracts 1909-

Kanekal, S. G., J. F. Fennell, D. N. Baker, and K. K. Davis. 2010. Loss Of Relativistic Electrons In The Inner Magnetosphere Via Wave Particle Interactions AGU Fall Meeting Abstracts 2-

Presicci, M. R., D. N. Baker, and S. G. Kanekal. 2010. Variations of Earth's radiation belt intensities on time scales of days throughout the 11-year solar cycle AGU Fall Meeting Abstracts A1791-

Selesnick, R. S., and S. G. Kanekal. 2009. Variability of the total radiation belt electron content Journal of Geophysical Research (Space Physics) 114 [2203-10.1029/2008JA013432]

Farr, N. L., D. Baker, S. G. Kanekal, and X. Li. 2009. A Remarkable Natural Experiment: The Extremely Quiet Sun (2007-2009) and its Effect on Earth's Radiation Belts AGU Fall Meeting Abstracts 5-

Kanekal, S. G., J. Fennell, D. Baker, and J. B. Blake. 2009. Systematics of Electron Flux Decay Lifetimes in the Outer Radiation Belts AGU Fall Meeting Abstracts A1584-

Fennell, J., J. L. Roeder, and S. G. Kanekal. 2009. Evolution and Energization of Energetic Electrons in the Inner Magnetosphere: July 2004 Storms AGU Fall Meeting Abstracts A1587-

Baker, D. N., and S. G. Kanekal. 2008. Solar cycle changes, geomagnetic variations, and energetic particle properties in the inner magnetosphere Journal of Atmospheric and Solar-Terrestrial Physics 70 195-206 [10.1016/j.jastp.2007.08.031]

Baker, D. N., R. B. Horne, N. P. Meredith, S. G. Kanekal, and S. A. Glauert. 2008. Low-altitude measurements of 2-6 MeV electron trapping lifetimes in the range of L between 1.5 and 2.5 37th COSPAR Scientific Assembly 37 170-

Baker, D. N., S. G. Kanekal, H. E. Spence, J. Westfall, and V. Hoxie. 2008. The Relativistic Electron-Proton Telescope (REPT) 37th COSPAR Scientific Assembly 37 168-

Kanekal, S. G., M. Al-Dayeh, M. Desai, H. A. Elliott, and B. Klecker. 2008. Relating Solar Energetic Proton Populations Observed Within the Terrestrial Magnetosphere to Coronal Mass Ejections, Magnetic Flux Ropes observations at 1 AU AGU Fall Meeting Abstracts 1643-

Baker, D. N., S. G. Kanekal, J. P. McCollough, et al. H. J. Singer, S. P. Chappell, and J. H. Allen. 2008. Adverse Space Weather at the Solar Cycle Minimum AGU Spring Meeting Abstracts 5-

Johnston, W. R., P. C. Anderson, J. Goldstein, S. G. Kanekal, and T. P. OBrien. 2007. The Role of the Plasmasphere in Radiation Belt Particle Energization and Loss AGU Spring Meeting Abstracts A7-

Kanekal, S. G., R. S. Selesnick, D. N. Baker, and J. B. Blake. 2007. Observational constraints on relativistic electron dynamics: temporal evolution of electron spectra and flux isotropization AGU Spring Meeting Abstracts A3-

Baker, D. N., S. G. Kanekal, R. B. Horne, N. P. Meredith, and S. A. Glauert. 2007. Low-altitude measurements of 2-6 MeV electron trapping lifetimes at 1.5 <= L <= 2.5 Geophysical Research Letters 34 [20110-10.1029/2007GL031007]

Baker, D. N., S. G. Kanekal, R. B. Horne, N. P. Meredith, and S. A. Glauert. 2007. Low-altitude Measurements of 2-6 MeV Electron Trapping Lifetimes at 1.5 < L < 2.5 AGU Fall Meeting Abstracts A6-

Kanekal, S. G., D. N. Baker, and R. McPherron. 2007. The seasonal dependence of relativistic electron fluxes in the Earth's outer van Allen Belt AGU Fall Meeting Abstracts A318-

Johnston, W. R., P. C. Anderson, J. Goldstein, T. P. OBrien, and S. G. Kanekal. 2007. Dynamics of the Plasmasphere and the Outer Radiation Belt AGU Fall Meeting Abstracts A323-

Kanekal, S. G., M. D. Looper, D. N. Baker, and J. B. Blake. 2006. Study of Proton cutoffs during geomagnetically disturbed times 36th COSPAR Scientific Assembly 36 570-

Baker, D. N., C. E. Randall, C. A. Barth, et al. S. G. Kanekal, C. Saetre, and S. M. Bailey. 2006. Observations of magnetospheric particles during large storms and assessing their effects on the Earth's atmosphere 36th COSPAR Scientific Assembly 36 686-

Kanekal, S. G., R. S. Selesnick, D. N. Baker, and J. B. Blake. 2006. Evolution of electron spectra and flux isotropization during electron energization in the inner magnetosphere 36th COSPAR Scientific Assembly 36 1693-

Shprits, Y. Y., R. M. Thorne, R. B. Horne, et al. S. A. Glauert, M. Cartwright, C. T. Russell, D. N. Baker, and S. G. Kanekal. 2006. Acceleration mechanism responsible for the formation of the new radiation belt during the 2003 Halloween solar storm Geophysical Research Letters 33 [5104-10.1029/2005GL024256]

Kanekal, S. G. 2006. A review of recent observations of relativistic electron energization in the Earth's outer Van Allen radiation belt Proceedings of the ILWS Workshop 274-

Kanekal, S. G., and D. N. Baker. 2006. High Latitude Energetic Particle Boundaries: The SAMPEX Database 2nd UN/NASA Workshop on International Heliophysical Year and Basic Space Science

Shprits, Y. Y., R. M. Thorne, R. Friedel, et al. G. D. Reeves, J. Fennell, D. N. Baker, and S. G. Kanekal. 2006. Outward radial diffusion driven by losses at magnetopause Journal of Geophysical Research (Space Physics) 111 [11214-10.1029/2006JA011657]

Davis, A. J., S. G. Kanekal, M. D. Looper, G. M. Mason, and R. A. Mewaldt. 2006. Integrating a Data Center and Resident Archive into the Emerging Virtual Observatiry System: Practical experience and perspectives AGU Fall Meeting Abstracts 4-

Vassiliadis, D., D. N. Baker, S. F. Fung, et al. S. G. Kanekal, E. J. Rigler, R. S. Selesnick, and R. S. Weigel. 2006. A modular radiation-belt electron flux model AGU Fall Meeting Abstracts A7-

Johnston, W. R., P. C. Anderson, J. Goldstein, S. G. Kanekal, and T. P. OBrien. 2006. Relationship Between the Plasmapause and the Outer Radiation Belt From DMSP, IMAGE, and SAMPEX Observations AGU Fall Meeting Abstracts 1491-

Kanekal, S. G., R. S. Selesnick, D. N. Baker, and J. B. Blake. 2006. Energetic electron spectra and flux isotropization during different phases of solar cycle AGU Fall Meeting Abstracts 1490-

Selesnick, R. S., and S. G. Kanekal. 2006. Variability of the outer radiation belt electron content AGU Fall Meeting Abstracts 1499-

Baker, D. N., S. G. Kanekal, J. B. Blake, and J. H. Allen. 2005. Radiation Belt Responses to the Solar Events of October-November 2003 Washington DC American Geophysical Union Geophysical Monograph Series 159 251-

Kanekal, S. G., R. S. Selesnick, D. N. Baker, and J. B. Blake. 2005. Observations of energy spectra and flux isotropization of relativistic electrons during energization events. to relativistic energies AGU Spring Meeting Abstracts 4-

Davis, A. J., G. M. Mason, P. Walpole, et al. T. T. von Rosenvinge, M. D. Looper, J. B. Blake, J. E. Mazur, E. C. Stone, R. A. Leske, A. W. Labrador, R. A. Mewaldt, S. G. Kanekal, D. N. Baker, X. Li, and B. Klecker. 2005. The SAMPEX Data Center and User Interface for the SEC Community AGU Spring Meeting Abstracts 1-

Baker, D. N., S. G. Kanekal, J. C. Green, T. G. Onsager, and J. C. Foster. 2005. Relativistic electron dropout events as observed concurrently by SAMPEX and GOES sensors: Relationships to plasmaspheric and ionospheric conditions AGU Spring Meeting Abstracts 4-

Green, J. C., T. G. Onsager, T. P. OBrien, et al. B. J. Fraser, H. J. Singer, A. J. Smith, D. N. Baker, S. G. Kanekal, E. J. Rigler, and R. H. Friedel. 2005. Relationship Between the Plasmasphere and Relativistic Electron Flux Depletions in Earth's Outer Radiation Belt AGU Spring Meeting Abstracts A3-

Kanekal, S. G., R. S. Selesnick, D. N. Baker, and J. B. Blake. 2005. Observations of energy spectra and flux isotropization of relativistic electrons during energization events. to relativistic energies AGU Spring Meeting Abstracts 4-

Baker, D. N., S. G. Kanekal, X. Li, and J. B. Blake. 2005. Solar cycle changes of energetic particle properties in the Earth's radiation belts AGU Spring Meeting Abstracts 5-

Green, J. C., S. G. Kanekal, R. S. Selesnick, D. N. Baker, and J. B. Blake. 2005. Energization of outer zone electrons:spectral evolution and flux isotropization AGU Fall Meeting Abstracts A4-

Kanekal, S. G., R. H. Friedel, G. D. Reeves, D. N. Baker, and J. B. Blake. 2005. Relativistic electron events in 2002: Studies of pitch angle isotropization Journal of Geophysical Research (Space Physics) 110 [12224-10.1029/2004JA010974]

Goldstein, J., S. G. Kanekal, D. N. Baker, and B. R. Sandel. 2005. Dynamic relationship between the outer radiation belt and the plasmapause during March-May 2001 Geophysical Research Letters 32 [15104-10.1029/2005GL023431]

Kanekal, S. G., M. D. Looper, D. N. Baker, and J. B. Blake. 2005. Study of Proton cutoffs during geomagnetically disturbed times AGU Fall Meeting Abstracts A284-

Rigler, E. J., D. N. Baker, D. Vassiliadis, and S. G. Kanekal. 2005. Studying Radiation Belt Electrons with Linear State-Space Models AGU Fall Meeting Abstracts 5-

Kanekal, S. G., R. H. Friedel, and E. G. Reeves. 2004. using multi-scale measurements of pitch angle distribution to test magnetospheric relativistic electron energization models 35th COSPAR Scientific Assembly 35 1003-

Monk, S., D. N. Baker, S. G. Kanekal, et al. X. Li, J. Goldstein, and J. L. Burch. 2004. Acceleration and extreme distortion within the Van Allen radiation belts during the 'Halloween' solar storms of 2003 AGU Fall Meeting Abstracts 5-

Hill, M. E., G. B. Vieira, D. C. Hamilton, et al. F. M. Ipavich, M. R. Collier, J. L. Green, M. Fok, T. E. Moore, and S. G. Kanekal. 2004. Energetic Neutral Atom Response to the Interaction Between the Solar Wind and the Dayside Magnetosphere During the Halloween 2003 Geomagnetic Storm AGU Spring Meeting Abstracts A8-

Vassiliadis, D., R. S. Weigel, D. N. Baker, S. G. Kanekal, and A. J. Klimas. 2004. Probing the solar wind-inner magnetospheric coupling: validation of relativistic electron flux models Journal of Atmospheric and Solar-Terrestrial Physics 66 1399-1409 [10.1016/j.jastp.2004.03.025]

Kanekal, S. G., R. S. Selesnick, D. N. Baker, and J. B. Blake. 2004. Characterizing Relativistic Electrons Flux Enhancement Events using sensors onboard SAMPEX and POLAR AGU Fall Meeting Abstracts A1109-

Baker, D. N., S. G. Kanekal, X. Li, et al. S. P. Monk, J. Goldstein, and J. L. Burch. 2004. An extreme distortion of the Van Allen belt arising from the `Hallowe'en' solar storm in 2003 Nature 432 878-881 [10.1038/nature03116]

Vassiliadis, D., A. J. Klimas, R. S. Weigel, et al. D. N. Baker, E. J. Rigler, S. G. Kanekal, T. Nagai, S. F. Fung, R. W. Friedel, and T. E. Cayton. 2003. Structure of Earth's outer radiation belt inferred from long-term electron flux dynamics Geophysical Research Letters 30 [2015-10.1029/2003GL017328]

Kanekal, S. G., D. N. Baker, J. B. Blake, et al. M. D. Looper, R. A. Mewaldt, and C. A. Lopate. 2003. Modulation of Jovian electrons at 1 AU during solar cycles 22-23 Geophysical Research Letters 30 [1795-10.1029/2003GL017502]

Vassiliadis, D., S. F. Fung, A. J. Klimas, et al. X. Shao, D. N. Baker, S. G. Kanekal, R. S. Weigel, and E. J. Rigler. 2003. Modeling relativistic electron fluxes in the inner magnetosphere with spatially distributed models AGU Fall Meeting Abstracts 525-

Kanekal, S. G., R. H. Friedel, and G. D. Reeves. 2003. Global flux isotropization and in-situ Pitch angle evolution during relativistic electron energization in the outer zone AGU Fall Meeting Abstracts

Kanekal, S. G., R. H. Friedel, and G. D. Reeves. 2003. Global flux isotropization and in-situ Pitch angle evolution during relativistic electron energization in the outer zone AGU Fall Meeting Abstracts

Vassiliadis, D., A. J. Klimas, S. G. Kanekal, D. N. Baker, and R. S. Weigel. 2002. Long-term-average, solar cycle, and seasonal response of magnetospheric energetic electrons to the solar wind speed Journal of Geophysical Research (Space Physics) 107 [1383-10.1029/2001JA000506]

Baker, D. N., T. A. Fisher, C. A. Barth, et al. K. D. Mankoff, S. G. Kanekal, S. M. Bailey, S. M. Petrinec, J. G. Luhmann, G. M. Mason, J. E. Mazur, and D. S. Evans. 2002. Precipitating auroral electrons and lower thermospheric nitric oxide densities: SNOE, POLAR, SAMPEX, and NOAA/POES Comparisons for Geomagnetic Storms in 1998-2001 AGU Spring Meeting Abstracts A7-

Baker, D. N., R. A. Mewaldt, S. G. Kanekal, et al. M. G. Henderson, D. S. Evans, S. M. Bailey, M. J. Reiner, and B. R. Dennis. 2002. Tracing the Sun-Earth Connection: The Solar Particle Chain in April 2002 AGU Fall Meeting Abstracts 3-

Kanekal, S. G., D. N. Baker, J. B. Blake, and M. D. Looper. 2002. Observations of Jovian Electrons over the Earth's Polar regions: 1992-2001 AGU Spring Meeting Abstracts A11-

Rigler, E. J., D. N. Baker, D. Vassiliadis, S. G. Kanekal, and A. J. Klimas. 2002. Solar Wind-Driven Radiation Belt Response Functions at Sub-Daily Time Scales Using SAMPEX Orbit-Averaged Electron Fluxes AGU Spring Meeting Abstracts A10-

Vassiliadis, D., R. S. Weigel, A. J. Klimas, et al. S. F. Fung, S. G. Kanekal, D. N. Baker, E. J. Rigler, and R. H. Friedel. 2002. Structure of the outer zone of the electron radiation belt AGU Spring Meeting Abstracts A8-

Chaves, R. G., L. Kepko, H. E. Spence, and S. G. Kanekal. 2002. Are Pressure Variations in the Solar Wind Causally Related to Relativistic Electron Enhancements? AGU Spring Meeting Abstracts A9-

Kozyra, J. U., D. N. Baker, G. Crowley, et al. D. S. Evans, X. Fang, R. A. Frahm, S. G. Kanekal, M. W. Liemohn, G. Lu, G. M. Mason, R. A. Mewaldt, L. J. Paxton, E. C. Roelof, and J. D. Winningham. 2002. The Relative Atmospheric Impacts and Energy Inputs of Precipitating Solar and Magnetospheric Ion and Electron Populations during the 17-24 April 2002 Events AGU Fall Meeting Abstracts A7-

Kanekal, S. G., D. N. Baker, and J. B. Blake. 2002. Magnetospheric energetic particle response during the April 2002 event AGU Fall Meeting Abstracts 435-

Li, X., M. Temerin, D. N. Baker, et al. G. D. Reeves, D. Larson, and S. G. Kanekal. 2002. Dipole Tilt Effects on Radiation Belt Electrons and Dst Index AGU Fall Meeting Abstracts 8-

Vassiliadis, D., R. S. Weigel, A. J. Klimas, D. N. Baker, and S. G. Kanekal. 2002. Diffusion and injections in the radiation belts: L shell coupling AGU Fall Meeting Abstracts A504-

Kanekal, S. G., D. N. Baker, and J. B. Blake. 2001. Multisatellite measurements of relativistic electrons: Global coherence Journal of Geophysical Research 106 29721-29732 [10.1029/2001JA000070]

Kanekal, S. G., D. N. Baker, and J. B. Blake. 2001. Relativistic electron response to high speed solar wind streams and coronal mass ejections: A comparison AGU Fall Meeting Abstracts 835-

Baker, D. N., C. A. Barth, K. E. Mankoff, et al. S. G. Kanekal, S. M. Bailey, G. M. Mason, and J. E. Mazur. 2001. Relationships between precipitating auroral zone electrons and lower thermospheric nitric oxide densities: 1998-2000 Journal of Geophysical Research 106 24465-24480 [10.1029/2001JA000078]

Baker, D. N., S. G. Kanekal, J. B. Blake, and T. I. Pulkkinen. 2001. The global efficiency of relativistic electron production in the Earth's magnetosphere Journal of Geophysical Research 106 19169-19178 [10.1029/2000JA003023]

Li, X., D. N. Baker, S. G. Kanekal, and M. A. Temerin. 2001. Long Term Measurements of MeV Electrons by SAMPEX and Their Variations Associated with Solar Wind and Geomagnetic Storms AGU Spring Meeting Abstracts 42-

Li, X., D. N. Baker, S. G. Kanekal, M. Looper, and M. Temerin. 2001. Long term measurements of radiation belts by SAMPEX and their variations Geophysical Research Letters 28 3827-3830 [10.1029/2001GL013586]

Kanekal, S. G., D. N. Baker, J. B. Blake, et al. B. Klecker, G. M. Mason, and R. A. Mewaldt. 2000. Magnetospheric Relativistic Electron Response to Magnetic Cloud Events of 1997 Advances in Space Research 25 1387-1392 [10.1016/S0273-1177(99)00648-1]