Ku-Band High-Speed Scanning Doppler Radar for Volcanic Eruption Monitoring
Masayuki Maki*1,, Shinobu Takahashi*1, Sumiya Okada*2, Katsuyuki Imai*3,*4, and Hiroshi Yamaguchi*4
*1Research and Education Center for Natural Hazards, Kagoshima University
1-21-40 Korimoto, Kagoshima, Kagoshima 890-0065, Japan
*2NPO of RAIRAN, Osaka, Japan
*3Engineering Department, Hybrid Products Division, Sumitomo Electric Industries, Ltd., Osaka, Japan
*4Koiki Communication Systems Department, Communication System Division, Sumitomo Densetsu Co., Ltd., Osaka, Japan
This paper presents the major specifications and characteristics of the Ku-band high-speed scanning Doppler radar for volcano observation (KuRAD) introduced to Kagoshima University in March 2017 as well as the results of a test observation at Sakurajima. KuRAD is a Doppler radar for research with a wavelength of approximately 2 cm and uses a 45 cm diameter Luneberg lens antenna as a transmitting and receiving antenna to observe the development of a volcanic eruption column immediately following eruption at a maximum rotation speed of 40 rpm. The maximum transmitter power is 9.6 W and the maximum observational range is 20 km. Observed data includes radar reflectivity factor, Doppler velocity, and Doppler spectrum width. Another feature of KuRAD is an obtained radio station license for observation of a total of seven active volcanos in Kyushu. To assess the basic performance of KuRAD, we carried out test observations of volcanic eruptions at Sakurajima, Kagoshima Prefecture, Japan and collected a total of 87 eruptions (20 of which are explosive eruptions and 7 of which had 3,000 m or higher eruptive smoke from vents). From the eruption data of Showa vent on May 2, 2017, it was confirmed that KuRAD could monitor the three-dimensional internal structure of a volcanic eruption column immediately following eruption. Eruption data from Minamidake of Sakurajima on March 5, 2018, showed that KuRAD successfully observed the eruptive smoke reaching a height of 4,000 m, although the eruptive smoke was covered with clouds and could not be detected by optical instruments of the Japan Meteorological Agency.
-  K. Imai, Y. Ura, T. Nakagawa, T. Ushio, and Z. Kawasaki, “Development of High-Resolution Meteorological Radar System,” SEI Technical Review, Vol.173, pp. 105-108, 2008 (in Japanese with English abstract).
-  E. Yoshikawa, S. Kida, S. Yoshida, T. Morimoto, T. Ushio, and Z. Kawasaki, “Vertical structure of raindrop size distribution in lower atmospheric boundary layer,” Geophys. Res. Lett., Vol.37, No.20, L20802, doi:10.1029/2010GL045174, 2010.
-  E. Yoshikawa, “A Study of Meteorological Radar Network at Ku-band with High Resolution,” Doctoral Thesis, Osaka University, http://hdl.handle.net/11094/1398, 2011.
-  R. K. Luneburg, “Mathematical Theory of Optics,” University of California Press, p. 401, 1965.
-  A. D. Greenwood and J.-M. Jin, “A field picture of wave propagation in inhomogeneous dielectric lenses,” IEEE Antennas and Propagation Magazine, Vol.41, No.5, pp. 9-18, 1999. Animation: https://youtu.be/aURuC4Ur84Q?t=1
-  B. Myers and C. L. Driedger, “Geologic Hazards at Volcanoes,” U. S. Geological Survey, 2008 http://pubs.usgs.gov/gip/64 [accessed May 1, 2019]
-  M. Maki and T. Kobori, “Summary of Analytical Tools for Three-dimensional Radar Data for Volcanic Eruption (ANT3D),” Preprints of the MSJ Annual Scientific Meetings, Vol.111, D458, 2017 (in Japanese).
This article is published under a Creative Commons Attribution-NoDerivatives 4.0 International License.