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The, ocean microbarom is an acoustic signal generated via nonlinear interaction of ocean surface waves. It can propagate for thousands of kilometers and represent a significant infrasonic noise source for ground infrasound stations across the globe. However, wind noise often compromises detections at ground stations. Furthermore, the microbarom may travel in elevated acoustic ducts that do not transmit enough energy for detections on ground stations. Here the presence of the ocean microbarom on two high-altitude balloon flights is investigated. A spectral peak consistent with the microbarom was observed on sensors in the stratosphere but not on those deployed on the ground near the flight path of the balloon. This is probably due to an elevated acoustic duct and/or a superior signal-to-noise ratio in the stratosphere. Thus, microbarom activity quantified solely with ground-based sensors may underestimate the occurrence of the phenomenon. However, high levels of interference from flight system electronics and/other other payloads may have obscured other microbarom episodes during the balloon deployments.

Plain Language Summary Low-frequency sound from colliding ocean waves, called the ocean microbarom, can travel for thousands of kilometers and is detected throughout the world. However, interference from wind often swamps the signal on ground microphones. We show that microphones on high-altitude balloons are effective means of capturing this signal, and that these particular sound waves are easier to detect using airborne sensors. It is possible that ground-based studies fail to capture the full extent of ocean microbarom activity.