Validation of Acoustic Measurements of Wind and Precipitation Using Expendable Ambient Noise Sensor (ANS) Drifters, AN/WSQ-6 (XAN-2).
WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
Pagination or Media Count:
Air-deployable autonomous drifters have been developed to monitor upper ocean environmental conditions in remote or difficult regions. One version of these drifters ANWSO-6 series, model XAN-2 includes ambient noise measurements in 16 frequency bands from 5 Hz to 25 kHz. One application of this sensor is the passive identification and analysis of local weather conditions. This analysis is possible because breaking waves, related to wind speed or sea state, and precipitation produce loud and unique sound underwater. This report describes the performance of 15 of these ambient noise sensor ANS drifters deployed in a variety of water conditions at various locations around the world. Acoustically derived present weather conditions are compared with the Defense Meteorological Satellite Program DMSP passive microwave sensor SSMl images. While regional variations in the high frequency 25 kHz sound spectrum were observed, the acoustic measurement of wind speed using 8 kHz sound levels did not show regional or environmental variability. Overall, the correlation between the ANS and SSMl wind speed measurements is 0.91. Acoustically detected precipitation is verified by the SSMl sensors in 19 of 21 events 90.5. The ANS drifters did not detect light raindrizzle when the wind speed was greater than 10 ms.