Development of an L-band Lower Troposphere Radar (LTR)

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The purpose of this study is to develop an L-band lower troposphere radar (LTR) to observe the atmosphere in the whole lower troposphere.We first designed radar system, and developed a phased array antenna with a relatively large size of 4m×4m. Next transmitters, having the output power of 2kW, the band-width of 10 MHz, and the maximum duty ratio of 20%, were developed. The LTR was installed at the Shigaraki MU Observatory in 1999. We conducted simultaneous observations with the MU radar, a boundary layer radar, a Doppler sodar, an anemometer etc., and confirmed the reliability of the LTR observations. We developed RASS (Radio Acoustic Sounding System) using the LTR and eight speakers. Temperature profiles obtained by LTR/RASS were compared with radiosonde data launched at the MU Observatory. We investigated diurnal and seasonal variations of wind velocities and turbulence intensities obtained by the LTR.