Global Microbarom Patterns: A First Confirmation of the Theory for Source and Propagation

Abstract

Microbarom signals are generated by wind waves at the ocean surface and propagate all around the globe through the stratosphere and ionosphere. Microbaroms dominate the coherent infrasound ambient noise measured worldwide, with a peak around 0.2 Hz. Monitoring these signals allows characterizing the source activity and probing the properties of their propagation medium, the middle atmosphere. Here, we show the first quantitative validation of global microbarom modeling based on ocean wave models, a new source model and atmospheric attenuation. For evaluating these parameters' impact, we compare the modeling results with a global reference database of microbaroms detected by the infrasound International Monitoring System over 7 years. This study demonstrates that the new source model improves the prediction rate of observations by around 20% points against previous models. The performance is enhanced when the new model is combined with a wind-dependent attenuation and an ocean wave model that includes coastal reflection.