Potential of Infrasonic Observing Systems for Monitoring Mountain-Induced Turbulence

Measurements dating from the 1970's have shown sources of atmospheric infrasound related to high winds over mountain ranges and locations of pilot reports. More recently, the development of an infrasonic network, designed for evaluating tornado detection potential and operating at higher sub-audible frequencies, suggested taking a fresh look at infrasound related to airflow over mountains. Often the three observatories at Boulder, CO, Pueblo, CO and Goodland, KS will triangulate on a region along the front range of Colorado (sometimes to the north and sometimes to the south). There is evidence that frequencies from 0.5 to 1 Hz are related to acoustic sources above mountain top level, whereas, the frequency range from 1-5 Hz is correlated with more direct terrain/airflow interactions at lower altitudes. We review current measurements in the context of past measurements. We suggest possible uses for this information (which can be presented in essentially real time) and review current data visualization options. We have found that there are strong temporal and spatial changes in the sound radiated, which may reflect details of mountain/flow interactions and be valuable for guiding experiments, now casts, and predictions of turbulence aloft. Finally, we compare infrasonic data with potential sound generation mechanisms relating to mountain flows.