Phase scintillation observation during coronal sounding experiments with NOZOMI spacecraft

¹ Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara, Kanagawa 229-8510, Japan e-mail: ima@isas.jaxa.jp
² Nara Women's University, Kita-uoya Nishi-machi, Nara 630-8506, Japan
³ Institute of Radio Engineering and Electronics of the Russian Academy of Sciences, Russia
⁴ Solar-Terrestrial Environment Laboratory, Nagoya University, Honohara 3-13, Toyokawa, Aichi 442-8507, Japan

Received: 26 December 2004
Accepted: 11 April 2005

Abstract

Radio occultation observations of the solar corona at solar offset distances of 12.8–36.9 R_S were performed from December of 2000 to January of 2001, using the Nozomi spacecraft (Planet-B) of Japan. Phase scintillation spectra up to the frequency of ~10 Hz were obtained in two-way mode with S-band uplink and X-band downlink. The spectra cannot be represented by a single power law especially for small offset distances. That is, at low frequencies (large scales) the spectra show slopes indicative of Kolmogorov, a local flattening occurs from ~0.5 Hz (scale ~600 km) to ~3 Hz (~100 km), and a steepening occurs again at higher frequencies. This three-component nature of the spectrum was observed with a single method for the first time, although the spectral shape is variable and the three-component feature is not always evident.