The design and initial testing of an X-band Doppler Radar for monitoring hazardous winds for railroad system

On Japan railroads, wind conditions affect operating efficiency, infrastructure, and safe passage of people and freight. For instance, strong winds cause regional delays or shutdowns, and especially hazardous crosswinds may lead to overturn of railcars. Since sonic/cup anemometers densely cover on the railroads for operations through some wind speed thresholds (e.g., winds in excess of 30 ms-1), localized but hazardous wind phenomena are difficult to detect with the present system. In Japan, over the Sea of Japan side, severe storms occur frequently especially in winter season. The use of Doppler radar data for these storms, and associated hazardous wind phenomena such as tornadoes, downbursts, and gusty winds, is an important requirement. In order to assess the utility of Doppler radar for use in operational railroad systems, the East Japan Railway Company installed a X-band Doppler radar on the rooftop of the building of the Amarume Station (Yamagata Pref., Japan). It has a 30-km observation range, a 2.0 azimuth resolution, and a pulse length of 1.0 (0.5) micro-sec providing independent data points every 150 (75) m in range. It is operated in a PPI mode and the velocity dealiasing algorithm correctly dealiases velocities even in a complicated circulation including downbursts, thunderstorm outflows, and mesocyclones. In this presentation, we will introduce some key characteristics of this radar and an example of observations.