Abstract
The Indian Antarctic station Maitri (geog. 70‡45’S, 11‡45’E, geom. 66‡.03S, 53‡.21E) occupies a sub-auroral location during magnetically quiet conditions(Σκρ < 10), but attains an auroral position when the auroral oval shifts equatorwards with increasing strength of magnetic disturbance. At the latter times, triangulation with 3 fluxgate magnetometers located at the vertices of a suitable triangle provides a means of monitoring mobile auroral ionospheric current systems over Maitri. The spacing between the magnetometers is typically kept at 75–200 km, keeping in mind the scale-sizes of ∼ 100 km for these mobile current systems. This work reports the results of two triangulation experiments carried out around Maitri in January 1992 and January 1995, both during Antarctic summer. The velocities estimated for pulsations of the Pc4 and Pc5 type were about 0.59 km/sec in the direction 102‡.7 east of due north, in the first case, and about 1–3 km/sec in the second case in the east-west direction.
While several magnetometer arrays exist in the northern auroral regions (e.g., the Alberta array in Canada, the Alaskan array in the U.S. and the IMS Scandinavian array), there is no report in literature of triangulation through arrays in Antarctica, except for a one-day study by Neudegget al 1995 for ULF pulsations of the Pc1 and Pc2 type. The velocities obtained for the Pi3 type of irregular pulsations over Antarctica in the present study tally well with those obtained for northern auroral locations.
Similar content being viewed by others
References
Akasofu S-I, Wilson C R, Synder A L and Perrault P D 1971 Results from a meridian chain of observations in the Alaska sector, 1;Planet Space Sci.,19 497
Andre D and Baumjohann W 1982 Joint 2-D observations of ground magnetic and ionospheric electric fields associated with auroral current systems associated with eastward drifting omega bands;J. Geophys. 50 194–201
Boström R 1975 Mechanisms for driving Birkeland currents, Physics of the hot plasma in the magnetosphere (ed) B Hultguist and L Stenflo. (N.Y.: Plenum Press) 431–447
Buchert S, Haerendeal G and Baumjohann W 1990 A model for the electric fields and currents during a strong Ps6 pulsation event;J. Geophys. Res. 95 3733–3743
Dunlop I S, Menk F W, Hansen H J, Fraser B J and Morris R J 1994 A multistation study of long-period geomagnetic pulsations at cusp and boundary layer latitudes;J. Atmos. Terres. Phys. 56 667–679
Fukushima N 1974 Equivalent current pattern for a fieldaligned current into the auroral belt of enhanced electric conductivity Part I, Case of no charge — accumulation at the auroral zone boundaries;Rep. Ionos. Space Res. Japan 28 207–218
Fukushima N 1975 Equivalent current pattern for a field-aligned current into the auroral belt of enhanced electric conductivity, Part II, Case of charge accumulation at the auroral zone boundaries;Rep. Ionos. Space Res. Japan 29 31–38
Fukushima N 1976 Generalised theorem for no ground magnetic effect of conductivity currents connected with Pedersen currents in the uniform-conductivity ionosphere;Rep. Ionos. Space Res. Japan 30 35–40
Hanchinal A N, Jeeva K, Dhar A and Rajaram G 1996 Response of geomagnetic field at Indian Antarctic station Maitri to increasing electromagnetic disturbance in Geospace; 12thIndian Expedition to Antarctica Scientific Report DOD Technical Publication No. 10 47–57
Gorney D J 1991, Overview of auroral spatial scales; Auroral Physics (ed) C-I Meng, M J Rycroft and L A Frank, (Cambridge University Press) 325–334
Kawasaki K and Rostoker G 1979 Perturbation magnetic fields and current systems associated with eastward drifting auroral structures;J. Geophys. Res. 84 1464–1480
Kisabeth J L and Rostoker G 1973 Current flow in auroral loops and surges inferred from ground-based magnetic observations;J. Geophys. Res. 78 5573–5584
McPherron R L, Russell C T and Aubry M P 1973 Satellite study of magnetospheric substorms on 15 Aug 1968: Phenomenological model for substorm;J. Geophys. Res. 78 3131–3149
Neudegg D A, Borms G B, Traser B J, Menk F W, Morris R J, Hansen H J, Underwood M J 1995 Determination of Pc1-2 ULF wave velocity and direction using a closely spaced Antarctic magnetometer array;Australian National Antarctic Research Expedition Report 126–151
Opgenoorth H J, Pellinen R J, Mavrer H, Kuppers F, Heikkila W J, Kaila K U and Tanskane P 1980 Ground based observations of an onset of localised field-aligned currents during auroral break-up around magnetic midnight;J. Geophys. 48 101–115
Opgenoorth H J, Oksman J, Kaila K U, Nielsen E and Baumjohann W 1983 Characteristics of eastward drifting omega bands in the morning sector of the auroral ovalJ. Geophys. Res. 88 9171–9185
Opgenoorth H J and Baumjohann W 1984 Three dimensional current systems and electric fields during active aurora;Proc. Conf. Achievements of the IMS, 26–28 June 1984 Graz, Austria, ESA SP-217 (Sept 1984).
Rajaram G, Rostoker G and Samson J C 1986 Wave characteristics of Ps6 magnetic variations and their implications for convection flow in the magnetotail;Planet. Space Sci. 34 319–329
Raspopov O M, Chernous A and Kiselev B V 1971 High latitude geomagnetic field pulsations and their use in the identification of magnetospheric parameters;Geomagn. Aeron (Eng) 11 567–570
Saito T and Morioka A 1972 Dynamical characteristics of pulsating substorm Ps6;Proc. Symp. On Magnetospheric substorm, April 21–22, 1972 (Univ. of Tokyo: ISAS)
Singh Lakha, Vijaykumar P N, Garg S C, Tyagi T R, Bharadwaj R S, Dabas O P, Nagpal O P and Sengupta A 1977 Study of large and medium scale irregularities using 140 MHz ATS-6 Faraday rotation records from three stations;Indian Jr. Radio and Space Phys. 6 245–249
Tighe W G and Rostoker G 1981 Characteristics of westward travelling surge during magnetospheric substorms;J. Geophys. 50 51–67
Wiens R G and Rostoker G 1975 Characteristics of the development of the westward electrojet during the expensive phase of magnetospheric substorms;J. Geophys. Res. 80 2109–2128
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Rajaram, G., Hanchinal, A.N., Kalra, R. et al. Velocity of small-scale auroral ionospheric current systems over Indian Antarctic station Maitri. J Earth Syst Sci 111, 51–62 (2002). https://doi.org/10.1007/BF02702222
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF02702222