Development of a Ship-Borne Lower Troposphere Radar (SB-LTR)

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We have developed a wind profiler for lower tropospheric observations over the sea (Ship-Brone Lower Troposphere Radar : SB-LTR), besed on the L-band (1357.5 MHz) lower troposphere radar, which we previously developed. It is possible to vary the beam direction by electronically steering the zenith angle within 45 degrees, by using an active phased array antenna of 4m x 4m size. A peak output power of 2kW is obtained by 24 active transmitting modules. The SB-LTR was installed to the oceanographic research vessel MIRAI of JAMSTEC, Japan for test observations during February 22-March 22, 2004. A GPS navigational sensor and a three-axis angular sensor are deployed to provide necessary adjustments to wind profiles. During the observation, antenna beams were steered to vertical and four oblique directions with the zenith angle of 10 degrees. Time series data after conducting pulse-decoding and 128 coherent integrations were stored. The data such as roll, pitch, direction and speed of the ship simultaneously obtained were also stored for off-line analysis. We could successfully observed wind variations associated with the passage of the Madden-Julian oscillation.