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

为了研制L波段低对流层雷达（LTR），对整个低对流层大气进行观测，首先进行了雷达系统设计，并研制了4 m × 4 m的相控阵天线。接下来的发射机，具有2kW的输出功率，带宽为10 MHz，最大占空比为20%，被开发出来。LTR于1999年安装在Shigaraki MU天文台。我们用MU雷达、边界层雷达、多普勒声雷达、风速计等进行了同步观测，并证实了LTR观测结果的可靠性。我们使用LTR和八个扬声器开发了RASS（无线电声学探测系统）。将LTR/RASS获得的温度廓线与MU天文台发射的无线电探空仪数据进行了比较。我们研究了风速和湍流强度的日变化和季节变化的LTR。

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.