Earth Planets Space, Vol. 57 (No. 9), pp. 879-884, 2005

Investigation of electron density profile in the lower ionosphere by SRP-4 rocket experiment

K. Ishisaka¹, T. Okada¹, J. Hawkins², S. Murakami¹, T. Miyake¹, Y. Murayama³, I. Nagano⁴, and H. Matsumoto⁵

¹Toyama Prefectural University, Kosugi, Toyama 939-0398, Japan
²University of Alaska Fairbanks, Fairbanks, Alaska 99775-5919, U.S.A
³National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan
⁴Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
⁵Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto 611-0011, Japan

(Received October 23, 2003; Revised July 4, 2005; Accepted July 4, 2005)

Abstract: The SRP-4 rocket was launched at 12:07 LT on 18 March 2002. The objective of this rocket experiment is the investigation of the electron density profile in the high-latitude D-region of the ionosphere at noon. The Low frequency and Medium frequency band radio Receiver (LMR) and the DC Probe System (DPS) were installed on-board the rocket to estimate the D-region electron density. The LMR measured the intensities of radio waves received from ground-based stations operating at 257 kHz, 660 kHz and 820 kHz, respectively. The DPS measured the electron current and the positive ion current using the biased electrodes. The electron density profile at altitudes below 90 km was estimated from the measured absorption of these radio waves. It was found that the electron density began to increase at the altitude of 52 km and was larger than that estimated by the International Reference Ionosphere model at altitudes from 74 km to 89 km.
Key words: Propagation characteristic of radio wave, electron density, ionosphere, rocket experiment, full wave method.