References

ANGEO

Annales Geophysicae

ANGEO

Ann. Geophys.

1432-0576

Copernicus Publications

Göttingen, Germany

10.5194/angeo-32-1119-2014

Remote sensing of the Io torus plasma ribbon using natural radio occultation of the Jovian radio emissions

Boudjada

M. Y.

https://orcid.org/0000-0002-1934-7616

¹ Galopeau

P. H. M.

https://orcid.org/0000-0002-6114-672X

² Sawas

³ Lammer

Space Research Institute, Austrian Academy of Sciences, Graz, Austria

Université Versailles St-Quentin, CNRS/INSU, LATMOS-IPSL, Guyancourt, France

Institute of communications and wave propagation, University of Technology, Graz, Austria

09 09 2014

32 9 1119 1128

2014

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

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The full text article is available as a PDF file from https://angeo.copernicus.org/articles/32/1119/2014/angeo-32-1119-2014.pdf

We study the Jovian hectometric (HOM) emissions recorded by the RPWS (Radio and Plasma Wave Science) experiment onboard the Cassini spacecraft during its Jupiter flyby. We analyze the attenuation band associated with the intensity extinction of HOM radiation. This phenomenon is interpreted as a refraction effect of the Jovian hectometric emission inside the Io plasma torus. This attenuation band was regularly observed during periods of more than 5 months, from the beginning of October 2000 to the end of March 2001. We estimate for this period the variation of the electron density versus the central meridian longitude (CML). We find a clear local time dependence. Hence the electron density was not higher than 5.0 × 104 cm−3 during 2 months, when the spacecraft approached the planet on the dayside. In the late afternoon and evening sectors, the electron density increases to 1.5 × 105 cm−3 and reach a higher value at some specific occasions. Additionally, we show that ultraviolet and hectometric wavelength observations have common features related to the morphology of the Io plasma torus. The maxima of enhancements/attenuations of UV/HOM observations occur close to the longitudes of the tip of the magnetic dipole in the southern hemisphere (20° CML) and in the northern hemisphere (200° CML), respectively. This is a significant indication about the importance of the Jovian magnetic field as a physical parameter in the coupling process between Jupiter and the Io satellite.

References 1

Bagenal, F.: Empirical model of the Io plasma torus: Voyager measurements, J. Geophys. Res., 99, 11043–11062, 1994.

Bagenal, F. and Sullivan, J. D.: Direct plasma measurements in the Io torus and inner magnetosphere of Jupiter, J. Geophys. Res., 86, 8447–8466, 1981.

Bagenal, F., Crary, F. J., Stewart, A. I. F., Schneider, N. M., Gurnett, D. A., Kurth, W. S., Frank, L. A., and Paterson, W. R.: Galileo measurements of plasma density in the Io torus, Geophys. Res. Lett., 24, 2119–2122, 1997.

Barrow, C. H. and Desch, M. D.: Solar wind control of Jupiter's hectometric radio emission, Astron. Astrophys., 213, 495–501, 1989.

Bolton, S. and the Juno Team: The Juno Mission, in International Workshop on Instrumentation for Planetary Missions, European Planetary Science Congress, Contribution No. 1683, 2006.

Boudjada, M. Y., Galopeau, P. H. M., and Rucker, H. O.: Jovian hectometric beam observed by PWS and WAVES experiments on board Galileo and Wind spacecraft, Planet. Space Sci., 49, 1151–1158, 2001.

Boudjada, M. Y., Galopeau, P. H. M., Rucker, H. O., Lecacheux, A., Mebarki, N., Macher, W., and Voller, W.: Morphological aspects of the attenuation bands associated with Jovian hectometric radiation, J. Geophys. Res., 116, A11208, <a href="http://dx.doi.org/10.1029/2010JA016354">https://doi.org/10.1029/2010JA016354</a>, 2011.

Brown, M. E. and Bouchez, A. H.: The response of Jupiter's magnetosphere to an outburst on Io, Science, 278, 268–271, 1997.

Burke, B. F. and Franklin, K. L.: Observations of a variable radio source associated with planet Jupiter, J. Geophys. Res., 60, 213–217, 1955.

Esposito, L. W., Barth, C. A., Colwell, J. E., Lawrence, G. M., McClintock, W. E., Stewart, A. I. F., Keller, H. U., Korth, A., Lauche, H., Festou, M. C., Lane, A. L., Hansen, C. J., Maki, J. N., West, R. A., Jahn, H., Reulke, R., Warlich, K., Shemansky, D. E., and Yung, Y. L.: The Cassini Ultraviolet Imaging Spectrograph investigation, Space Sci. Rev., 115, 299–361, 2004.

Galopeau, P. H. M. and Boudjada, M. Y.: Solar wind control of Jovian auroral emissions, J. Geophys. Res., 110, A09221, <a href="http://dx.doi.org/10.1029/2004JA010843">https://doi.org/10.1029/2004JA010843</a>, 2005.

Galopeau, P. H. M., Boudjada, M. Y., and Rucker, H. O.: Evidence of Jovian active longitude: 1. Efficiency of cyclotron maser instability, J. Geophys. Res., 109, A12217, <a href="http://dx.doi.org/10.1029/2004JA010459">https://doi.org/10.1029/2004JA010459</a>, 2004.

Grasset, O., Dougherty, M. K., Coustenis, A., Bunce, E. J., Erd, C., Titov, D., Blanc, M., Coates, A., Drossart, P., Fletcher, L. N., Hussmann, H., Jaumann, R., Krupp, N., Lebreton, J.-P., Prieto-Ballesteros, O., Tortora, P., Tosi, F., and Van Hoolst, T.: JUpiter ICy moons Explorer (JUICE): An ESA mission to orbit Ganymede and to characterise the Jupiter system, Planet. Space Sci., 78, 1–21, 2013.

Green, J. L., Thieman, J. R., Higgins, C., Fung, S. F., Candey, R. M., and Aist-Sagara, L.: Lane features in Jovian hectometric radio emissions, in Planetary Radio Emissions III, edited by: Rucker, H. O., Bauer, S. J., and Kaiser, M. L., p. 91, Austrian Acad. of Sci. Press, Vienna, 1992.

Gurnett, D. A., Kurth, W. S., Roux, A., Bolton, S. J., and Kennel, C. F.: Galileo plasma wave observations in the Io plasma torus near Io, Science, 274, 391–392, 1996.

Gurnett, D. A., Kurth, W. S., Menietti, J. D., and Persoon, A. M.: An unusual rotationally modulated attenuation band in the Jovian hectometric radio emission spectrum, Geophys. Res. Lett., 25, 1841–1844, 1998.

Gurnett, D. A., Kurth, W. S., Kirchner, D. L., Hospodarsky, G. B., Averkamp, T. F., Zarka, P., Lecacheux, A., Manning, R., Roux, A., Canu, P., Cornilleau-Wehrlin, N., Galopeau, P., Meyer, A., Bostrom, R., Guastafsson, G., Wahlund, J.-E., Aahlen, L., Rucker, H. O., Ladreiter, H. P., Macher, W., Woolliscroft, L. J. C., Alleyne, H., Kaiser, M. L., Desch, M. D., Farrell, W. M., Harvey, C. C., Louarn, P., Kellogg, P. J., Goetz, K., and Pedersen, A.: The Cassini radio and plasma wave science investigation, Space Sci. Rev., 114, 395–463, 2004.

Higgins, C. A., Green, J. L., Thieman, J. R., Fung, S. F., and Candey, R. M.: Structure within Jovian hectometric radiation, J. Geophys. Res., 100, 19487–19496, 1995.

Higgins, C. A., Thieman, J. R., Fung, S. F., Green, J. L., and Candey, R. M.: Latitudinal structure within Jovian hectometric radiation, J. Geophys. Res., 103, 26679–26686, 1998.

Kaiser, M. L.: A low frequency radio survey of the planets with RAE 2, J. Geophys. Res., 82, 1256–1260, 1977.

Krüger, H., Geissler, P., Horányi, M., Graps, A. L., Kempf, S., Srama, R., Moragas-Klostermeyer, G., Moissl, R., Johnson, T. V., and Grün, E.: Jovian dust streams: A monitor of Io\'s volcanic plume activity, Geophys. Res. Lett., 30, 2101, <a href="http://dx.doi.org/10.1029/2003GL017827">https://doi.org/10.1029/2003GL017827</a>, 2003.

Kupo, I., Mekler, Y., and Eviatar, A.: Detection of ionized sulfur in the jovian magnetosphere, Astrophys. J., 205, L51–L54, 1976.

Leblanc, Y. and Daigne, G.: Broadband Jovian kilometric radiation: New results on polarization and beaming, J. Geophys. Res., 90, 12073–12080, 1985.

Lecacheux, A.: Ray tracing in the Io plasma torus: Application to the PRA observations during Voyager 1 \'s closest approach, J. Geophys. Res., 86, 8523–8528, 1981.

Lecacheux, A. and Ortega-Molina, A.: Polarization and localization of the Uranian radio sources, J. Geophys. Res., 92, 15148–15158, 1987.

Menietti, J. D., Gurnett, D. A., Spencer, J. R., and Stansberry, J. A.: Relationship between Jovian hectometric attenuation lanes and Io volcanic activity, Radio Sci., 36, 1723–1731, 2001.

Menietti, J. D., Gurnett, D. A., Hospodarsky, G. B., Higgins, C. A., Kurth, W. S., and Zarka, P.: Modeling radio emission attenuation lanes observed by the Galileo and Cassini spacecraft, Planet. Space Sci., 51, 533–540, 2003.

Ortega-Molina, A. and Lecacheux, A.: Polarization of Jovian hectometric emission, J. Geophys. Res., 96, 11441–11453, 1991.

Steffl, A. J., Stewart, A. I. F., and Bagenal, F.: Cassini UVIS observations of the Io plasma torus. I. Initial results, Icarus, 172, 78–90, 2004a.

Steffl, A. J., Bagenal, F., and Stewart, A. I. F.: Cassini UVIS observations of the Io plasma torus. II. Radial variations, Icarus, 172, 91–103, 2004b.

Steffl, A. J., Delamere, P. A., and Bagenal, F.: Cassini UVIS observations of the Io plasma torus. III. Modeling temporal and azimuthal variability, Icarus, 180, 124–140, <a href="http://dx.doi.org/10.1016/j.icarus.2005.07.013">https://doi.org/10.1016/j.icarus.2005.07.013</a>, 2006.

Steffl, A. J., Delamere, P. A., and Bagenal, F.: Cassini UVIS observations of the Io plasma torus. IV. Observations of temporal and azimuthal variability, Icarus, 194, 153–165, <a href="http://dx.doi.org/10.1016/j.icarus.2007.09.019">https://doi.org/10.1016/j.icarus.2007.09.019</a>, 2008.

Warwick, J. W., Pearce, J. B., Riddle, A. C., Alexander, J. K., Desch, M. D., Kaiser, M. L., Thieman, J. R., Carr, T. D., Gulkis, S., Boischot, A., Harvey, C. C., and Pedersen, B. M.: Voyager-1 planetary radio astronomy observations near Jupiter, Science, 204, 995–998, 1979.

Wu, C. S. and Lee, L. C.: A theory of the terrestrial kilometric radiation, Astrophys. J., 230, 621–626, 1979.