Infrasound from tornadoes and other severe storms Free

Infrasound arrays have been used for a long time to detect and monitor man‐made and natural acoustic sources below 20 Hz. Much of the earlier work on infrasound from severe weather was below 0.1 Hz and was related to severe weather penetrating the tropopause. It was noticed when violent thunderstorms passed near an array that a coherent signal would be detected coming from the same direction as the storm. By correlating the measurements with visual, satellite, and Doppler radar observations, the characteristics of the storm could be studied to determine what type of storm would cause the production of infrasound. Most of the storms that would produce an infrasonic signal were the strong supercell‐type storms that produced intense gust fronts and tornadoes. More recent measurements at frequencies above 0.1 Hz have been associated with tornadoes and tornadic storms. Following on these observations, NOAA established an infrasonic network to evaluate the use of infrasound for tornado detection and warning. This network has operated since 2003 and is still being optimized and evaluated. This talk will cover the studies that have been conducted and numerical models developed to try and explain this phenomenon.