Update on using metal domes for wind noise reduction at infrasonic frequencies

Abstract

The utility of infrasound for long range monitoring applications such as remote chemical explosions, or natural sources of infrasound such as tornadoes, volcanoes or hurricanes, continues to be hampered by the high noise floors experienced in the presence of high winds. Wind noise is typically filtered using pipe arrays. But these generate significant distortion, making them non-ideal for signals with significant frequency content above a few Hz, and do not produce sufficient noise reduction during windy measurements even at their optimal frequency band (0.5–1 Hz), making their utility generally limited to low-wind-noise periods. We present here an update on resesarch performed by the National Center for Physical Acoustics (NCPA) using field sites near Oxford (University of Mississippi Field Staiton) and at the Sandia National Laboratory Facility for Acceptance, Calibration, and Testing (FACT) site. The 20-foot dome at the FACT site is collocated with an IMS 18-m rosette filter and a wind noise filter developed by the University of Alaska Fairbanks. We compare in this presentation the relative performance of traditional pipe arrays to the 20-ft dome. The performance of smaller wind domes, including 42-in.2 perferorated metal domes developed at the NCPA, are also discussed.