A Study of quarter-wave mode standinf Alfven waves using data from a new magnetometer array in New Zealand

2014 Fiscal Year Final Research Report

• Project/Area Number: 24740333
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Space and upper atmospheric physics
• Research Institution: Osaka Electro-Communication University
• Principal Investigator: OBANA Yuki 大阪電気通信大学, 工学部, 講師 (50398096)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 磁気圏ー電離圏結合 / プラズマ圏 / 空洞共鳴 / 磁力線共鳴 / ULF波 / 国際情報交換

Outline of Final Research Achievements

In order to examine the resonance structure of quarter-wave mode standing Alfven waves, we constructed a new magnetometer array in New Zealand and data from this array were analyzed. Four events are discussed which show extraordinarily low eigenfrequencies, wide resonance widths, and strong damping when the ionosphere above New Zealand was in darkness while the conjugate northern hemisphere ionosphere was sunlit. The wide resonance width and the strong damping of the quarter-wave mode arise from strong energy dissipation in the dark side ionosphere. One event exhibited field line resonance structure continuously through a transition from very low frequency to the normal daytime values. The frequency change began when the dawn terminator passed over New Zealand and finished one hour later. These experimental results were compared with the ULF wave fields obtained from a 2.5-dimensional simulation model.

Free Research Field

磁気圏物理学