Tropical Cyclone Wind Speed Inversion Using Seafloor Rayleigh-Wave Microseisms

The accurate monitoring and prediction of tropical cyclone (TC) intensity remains a challenging issue in meteorology due to the lack of reliable in situ observations during such severe weather events. Microseisms have recently been successfully used as a proxy to locate TC tracks. However, TC intensity inversions using microseisms have not been reported to date. Here, we present the first documented inversion of the relationship between the TC intensity and triggered seafloor microseisms using the continuous seismic waveforms from a large-scale ocean bottom seismometer array surrounding La Réunion Island, Southwest Indian Ocean, during the passage of TC Dumile (2013). A mathematical model of the relationship between the observed seafloor Rayleigh-wave microseism strengths and maximum sustained wind speed is constructed, with these two parameters exhibiting a power-law behavior. The wind speed inversion takes into account the lag time between TC processes and microseism excitation, as well as the compensation for propagation loss of the TC-generated microseisms, following an extensive examination of the optimal frequency band and dominant source regions. The inversion results yield an average error of about 0.85 m/s compared to the maximum sustained wind speed from the best-track data. The results demonstrated that seafloor microseisms can potentially be used for undersea remote sensing of ocean storms and TC intensity inversions, thereby providing an interdisciplinary complement to traditional atmospheric and oceanic observations.