抄録
The Doppler weather radar on board the research vessel Mirai, which was installed in 1998, was replaced by a dual-polarization Doppler weather radar in 2014. This study explores the beam blockage for both radars on board the Mirai. Reflectivity data from long-term observations were used to calculate the probability of detection (POD) at a given range, azimuth, and elevation relative to the Mirai. Azimuthal sectors suffering from beam blockage caused by the infrastructure of the Mirai were characterized by pronounced minima of the POD in their centers and significant discontinuities of the POD on their edges. An objective method was developed to ascertain the boundaries of the blocked sectors based on the rate of change of the POD gradient along the azimuthal direction. According to the distinct signatures of the POD, detailed beam blockage information for both radars was identified in different ship-relative elevations. Although beam blockage for both radars occurred from low to high elevations, the total azimuths of the low-level blocked sectors for the dual-polarization Doppler radar decreased by more than half. This improvement was attributed to the higher location of the antenna for the dual-polarization Doppler radar. This accurate beam blockage information will facilitate the quality control of the Mirai radar data.
