Japan Geoscience Union Meeting 2015

Presentation information


Symbol P (Space and Planetary Sciences) » P-CG Complex & General

[P-CG32] Planetary atmosphere, ionosphere and magnetosphere

Tue. May 26, 2015 9:00 AM - 10:45 AM A03 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Takeshi Imamura(Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science), Kanako Seki(Solar-Terrestrial Environment Laboratory, Nagoya University), Yukihiro Takahashi(Department of Cosmosciences, Graduate School of Science, Hokkaido University), Yoshiyuki O. Takahashi(Graduate School of Science, Kobe University), Keiichiro Fukazawa(Academic Center for Computing and Media Studies, Kyoto University), Hiromu Nakagawa(Planetary Atmosphere Physics Laboratory, Department of Geophysics, Graduate School of Science, Tohoku University), Chair:Keiichiro Fukazawa(Academic Center for Computing and Media Studies, Kyoto University)

10:30 AM - 10:45 AM

[PCG32-17] Fine structure of Jupiter's decametric modulation lanes observed by LWA1

*Kazumasa IMAI1, Yoshiaki SHIMANOUCHI1, Masafumi IMAI2, Tracy Clarke3, Charles A. Higgins4 (1.Kochi National College of Technology, 2.Kyoto University, 3.Naval Research Laboratory, 4.Middle Tennessee State University)

Keywords:Jupiter radio, decametric wave, modulation lane, fine structure

The Long Wavelength Array (LWA) is a low-frequency radio telescope designed to produce high-sensitivity, high-resolution images in the frequency range of 10-88 MHz. The Long Wavelength Array Station 1 (LWA1) is the first LWA station completed in April 2011, and is located near the VLA site in New Mexico, USA. LWA1 consists of a 256 element array, operating as a single-station telescope.
The sensitivity of the LWA1 combined with the low radio frequency interference environment allow us to observe the fine structure of Jupiter's decametric modulation lanes. At frequencies in the vicinity of 22 MHz, most modulation lane patterns have frequency-time slopes between +100 and +180 kHz/sec for Io-B storms and between -90 and -200 kHz/sec for Io-A and Io-C storms. The lanes generally display a strong periodicity in time, with periods ranging from about 1 to 5 sec and an average of about 2 sec.
We refer to the modulation lanes possessing frequency-time slopes and periodicity within the above ranges as the major component. There is a minor modulation lane component, representing a considerably smaller fraction of the total number observed, for which the frequency-time slopes are of opposite sign than for the major component or are of the same sign but of smaller absolute value. For these cases the lanes are usually broader and their separations in time are longer.
There are significant differences of characteristics between the major and the minor components of modulation lanes. Minor component lanes are apparently of somewhat different origin from major component lanes. We show the fine structure of the major and minor modulation lanes observed by the LWA1. The origin of minor modulation lanes is discussed.