VHF observations on lightning discharges from a small satellite and the International Space Station
Abstract
We present the lightning observation missions from space which was conducted by Maido-1 satellite in 2009 and will be done from the international space station (ISS) in 2012. In our research group, the Broadband Digital Interferometer (DITF) has been already used to observe the lightning activities as a ground-based equipment. The DITF makes it possible to visualize lightning channel by the very high frequency (VHF) radio observations. The remarkable feature of the DITF is its ultra-wide bandwidth (from 25 MHz to 100 MHz) and implicit redundancy for the direction-of-arrival (DOA) estimation. Our final goal is to realize the space borne DITF and to monitor the thunderstorm activities constantly with the satellites. A small satellite, Maido-1 was launched on 23 January 2009. The satellite carries the radio-frequency payload (VHF sensor) for the research on lightning discharges.The VHF sensor was carried on the Maido-1 satellite and designed to examine the feasibility of space-borne DITF by receiving VHF lightning impulses in the orbit at an altitude of 660 km. It also extends one's knowledge of the radio propagation characteristics through the ionosphere. The sensor consists of a monopole antenna, a band-pass filter, an amplifier and an analog-to-digital (A/D) converter. The sensor makes it possible to record the waveform data of VHF impulses with the duration of 2.5 microseconds from a lightning flash. In 2012, global lightning and sprite measurements (GLIMS) mission is scheduled on Exposed Facility of Japanese Experiment Module (JEM-EF) of ISS which is at an altitude of 400 km. The VHF broadband digital interferometer (VITF) attached on JEM-EF is designed to estimate the direction of arrival with about 10 km resolution. The VITF is its bandwidth (from 70 MHz to 100 MHz). We will introduce the outline of the two missions and show the several observational results with the Maido-1 satellite and discuss the VHF wave propagation characteristics through the ionosphere. Using the numerical calculations, the change of the impulsive waveform of the VHF waves through the ionosphere will be indicated and compared with the satellite observations. In addition, the initial observational results with the VITF of the JEM- GLIMS mission will be presented.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMAE23A0314K
- Keywords:
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- 0600 ELECTROMAGNETICS;
- 2487 IONOSPHERE / Wave propagation;
- 3304 ATMOSPHERIC PROCESSES / Atmospheric electricity;
- 3324 ATMOSPHERIC PROCESSES / Lightning