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Characteristics of discrete VLF falling-tone chorus emissions observed at low latitude ground station Jammu

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The discrete VLF chorus emissions recorded at low latitude ground station Jammu (geomag. lat. = 22°26′N, L = 1.17) are reported and their characteristics based on spectral analysis have been carried out. These discrete chorus emissions are falling tone emissions which are rarely observed at low latitude ground stations. These discrete chorus emissions are generated during a strong geomagnetic storm period of 2–7 May, 1998. We have computed the frequency sweep rate, repetition period and source region of the individual chorus elements. It is observed that the sweep rate increases with time.


  1. Andronov, A. A. and V. Y. Trakhtengerts, Kinetic instability of Earth’s outer radiation belt, Geommagn. Aeron., 4, 233–242, 1964.

  2. Bortnik, J., R. M. Thorne, and N. P. Meredith, The unexpected origin of plasmaspheric hiss from discrete chorus emissions, Nature, 452(6), doi:10.1038/nature06741, 2008.

  3. Burtis, W. J. and R. A. Helliwell, Magnetospheric Chorus: Occurance pattern and normalized frequency, Planet. Space Sci., 24, 1007–1024, 1976.

  4. Cornilleau-Wehrlin, N., F. Gendrin, R. Lefeuvre, M. Parrot, R. Garad, and D. Jones, VLF waves observed on GEOS-I, Space Sci. Rev., 22, 371–382, 1978.

  5. Hattori, K. and M. Hayakawa, Consideration of dynamic spectra and direction finding results of hiss triggered chorus emissions, Proc. NIPR Symp., Upper Atmosphere Phys., 7, 40–52, 1994.

  6. Hattori, K., M. Hayakawa, D. Lagoutte, M. Parrot, and F. Lefeuvre, Further evidence of triggered chorus emissions from wavelets in the hiss band, Planet. Space Sci., 39, 1465–1472, 1991.

  7. Helliwell, R. A., Whistler and Related Ionospheric Phenomena, Stanford Univ. Press, Stanford, USA, 1965.

  8. Helliwell, R. A., A theory of discrete emissions from magnetosphere, J. Geophys. Res., 72, 4773–4790, 1967.

  9. Karpman, V. I., Non linear effects in the ELF waves propagating along the magnetic field in magnetosphere, Space Sci. Rev., 16, 361–388, 1974.

  10. Kennel, C. F. and H. E. Petschek, Limit on stably trapped particle fluxes, J. Geophys. Res., 71, 1–28, 1966.

  11. Lauben, D. S., U. S. Inan, T. F. Bell, and D. A. Gurnett, Source characteristic of ELF/VLF chorus, J. Geophys. Res., 107(A12), 1429–1446, 2002.

  12. Nunn, D., A self-consistent theory of triggered VLF emissions, Planet. Space Sci., 22, 349–378, 1974.

  13. Omura, Y., Y. Katoh, and D. Summers, Theory and simulation of the generation of whistler-mode chorus, J. Geophys. Res., 113, A04223, doi:10.1029/2007JA012622, 2008.

  14. Santolik, O., New results of investigations of whistler-mode chorus emissions, Nonlinear Processes Geophys., 15, 621–630, 2008.

  15. Santolik, O. and D. A. Gurnett, Transverse dimensions of chorus in the source region, 30, 1031, 2003.

  16. Sazhin, S. S. and M. Hayakawa, Magnetospheric chorus emissions: a review, Planet. Space Sci., 40, 681–697, 1992.

  17. Singh, A. K. and K. Ronnmark, A generation mechanism for VLF chorus emisions observed at low latitude ground station, Ann. Geophys., 22, 2067–2072, 2004.

  18. Singh, A. K. and R. P. Singh, Observations of discrete VLF emissions at low latitudes and their generation mechanism, Earth Planets Space, 56, 1067–1074, 2004.

  19. Singh, R. P. and R. P. Patel, Hiss-triggered chorus emissions at Indian stations, J. Atmos. Sol.-Terr. Phys., 66, 1027–1033, 2004.

  20. Singh, R., R. P. Patel, R. P. Singh, and Lalmani, An experimental study of hiss triggered chorus emissions at low latitude, Earth Planets Space, 52(1), 37–40, 2000.

  21. Singh, S., R. P. Patel, K. K. Singh, A. K. Singh, and R. P. Singh, Role of geomagnetic disturbances on VLF whistler wave activity at low latitudes, Planet. Space Sci., doi.10.1016/pss-2007.02.001, 2007.

  22. Smirnova, N. A., A fine structure of the ground observed VHF chorus as an indicator of the wave particle interaction process in the magnetosphere, Planet. Space Sci., 32(4), 425–438, 1984.

  23. Smirnova, N. A., P. Yu. Novkov, N. G. Kleimenova, and E. E. Titova, Some spectral peculiarities of VLF emissions registered on the Earth surface near the plasmapause projection, J. Atmos. Terr. Phys., 38, 1247, 1976.

  24. Smith, A. J., M. P. Freeman, and G. D. Reeves, Post midnight VLF chorus events, a substorm signature observed at the ground near L = 4, J. Geophys. Res., 101(A11), 24641–24653, 1996.

  25. Titova, E. E., B. V. Kozelov, F. Jiricek, A. G. Demekhov, and V. Yu. Traktengerts, Verification of the backward wave oscillator model of VLF chorus generation using data from MAGION 5 satellite, Ann. Geophys., 21, 1–9, 2003.

  26. Trakhtengerts, V. Y., Magnetosphere cyclotron maser: Backward wave oscillator generation regime, J. Geophys. Res., 100(A9), 17205–17210, 1995.

  27. Trakhtengerts, V. Y., A generation mechanism for chorus emissions, Ann. Geophys., 17, 95–100, 1999.

  28. Trakhtengerts, V. Y., A. G. Demekhov, E. E. Titova, B. V. Kozelov, O. Santolik, E. Macusova, D. Gurnett, J. S. Pickett, M. J. Rycroft, and D. Nunn, Formation of VLF chorus frequency spectrum: Cluster data and comparison with the backward wave oscillator model, Geophys. Res. Lett., 34, L02104, doi:10.1029/2006 GL027953, 2007.

  29. Tsurutani, B. T. and E. J. Smith, Post midnight chorus: a substorm phenomenon, J. Geophys. Res., 79, 118–127, 1974.

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Correspondence to Ashutosh K. Singh.

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Singh, A.K., Patel, R.P., Singh, R. et al. Characteristics of discrete VLF falling-tone chorus emissions observed at low latitude ground station Jammu. Earth Planet Sp 61, 1179–1183 (2009) doi:10.1186/BF03352969

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Key words

  • VLF emissions
  • whistler-mode waves
  • geomagnetic storm