Rain attenuation characteristics of Ku-band satellite signals in relation to the wind velocities observed on the ground

The direction and speed of rain area motions are estimated from the time differences in the Ku-band satellite signal attenuation detected at the three locations of Osaka Electro-Communication University (OECU, Neyagawa, Osaka), the Research Institute for Sustainable Humanosphere (Uji, Kyoto), and the Shigaraki MU radar observatory (Koga, Shiga) of Kyoto University. The direction and speed of the rain areas are compared with those of the ground wind velocities observed by AMeDAS at the nearby station 6.7 km north-east from OECU during the year of 2010. Although the simultaneous observations have only eight examples in this year, considerable correlations are found between the rain area motions and the ground wind velocities, suggesting that the direction and speed of the rain areas which is important to site diversity techniques may be easily estimated from the ground wind velocity measurements such as AMeDAS. In the future, further observations of rain area motions and ground wind velocities are needed, and comparison of their directions and speeds should be made with much more examples of longer observational years. Also, direct measurements of upper air motions using the MU radar and other wind profiler networks around the three observational locations are highly desired, to investigate the relationship between rain area motions and wind velocities from the ground to rain height in more detail.