High resolution in situ wind and pressure measurements in winter tornadoes with LAWPS

The Shonai area railroad weather project will investigate fine-scale structure of wind gust dynamics and kinetics such as tornadoes, downbursts, and gustfronts. In this project, in order to improve our understanding of near-surface tornadic features, we developed a linear array of wind and pressure sensor system (LAWPS) for high resolution in situ measurements in winter tornado cores. The pressure and wind sensors were deployed along a 500-m-long linear array that is located parallel to and about 100m from the shoreline. Wind data are obtained using six two- dimensional fast-response ultrasonic anemometers placed at a height of 5 m at intervals of 100 m. Pressure data are obtained using thirteen barometers placed at a height of 50cm at intervals of 50m. The pressure ports are designed and loaded to the barometers to reduce the dynamic pressure associated with wind and turbulence. Sampling intervals for both pressure and wind measurements are 100msec and the sampling are synchronized by the external trigger from data logging computer. In this presentation, the system overview and the measurement technique will be described, as well as three examples of actual winter tornado observations of the system and X-band Doppler radar simultaneously .