Quantifying hurricane wind speed with undersea sound

Abstract

Hurricanes, powerful storms with wind speeds that can exceed 80 m/s, are one of the most destructive natural disasters known to man. While current satellite technology has made it possible to effectively detect and track hurricanes, expensive 'hurricanehunting' aircraft are required to accurately classify their destructive power. Here we show that passive undersea acoustic techniques may provide a promising tool for accurately quantifying the destructive power of a hurricane and so may provide a safe and inexpensive alternative to aircraft-based techniques.It is well known that the crashing of wind-driven waves generates underwater noise in the 10 Hz to 10 kHz range. Theoretical and empirical evidence are combined to show that underwater acoustic sensing techniques may be valuable for measuring the wind speed and determining the destructive power of a hurricane. This is done by first developing a model for the acoustic intensity and mutual intensity in an ocean waveguide due to a hurricane and then determining the relationship between local wind speed and underwater acoustic intensity. Acoustic measurements of the underwater noise generated by hurricane Gert are correlated with meteorological data from reconnaissance aircraft and satellites to show that underwater noise intensity between 10 and 50 Hz is approximately proportional to the cube of the local wind speed. From this it is shown that it should be feasible to accurately measure the local wind speed and quantify the destructive power of a hurricane if its eye wall passes directly over a single underwater acoustic sensor. The potential advantages and disadvantages of the proposed acoustic method are weighed against those of currently employed techniques. It has also long been known that hurricanes generate microseisms in the 0.1 to 0.6 Hz frequency range through the non-linear interaction of ocean surface waves.Here we model microseisms generated by the spatially inhomogeneous waves of a hurricane with the non-linear wave equation where a second-order acoustic field is created by first-order ocean surface wave motion. We account for the propagation of microseismic noise through range-dependent waveguide environments from the deep ocean to a receiver on land. We compare estimates based on the ocean surface wave field measured in hurricane Bonnie with seismic measurements from Florida.

Seismic Remote Sensing of Super Typhoon Lupit (2009) with Seismological Array Observation in NE China

“…Although the microseisms induced by typhoons have been measured and tried to track typhoons historically early in 1940s [31,32], the link between ocean storms and their generated ambient noise including microseisms has recently become a frontier topic in the sphere of seismology and ocean acoustics [9,11,33,34]. Recent examples of these types of studies include analysis on both surface and body wave microseisms generated by the 2005 Hurricane Katrina in the Gulf of Mexico using 150 Southern California stations [1]; tracking of western Pacific typhoons in 2006 using seismic records from OBSs and on-land stations [4]; seismological observations of ocean storms in the South China and East China Sea [6]; investigations of the microseisms induced by the Superstorm Sandy in 2012 as it approached the US east coast using the Earthscope Transportable Array (TA) stations [7]; investigation of the DF microseisms generated by the 2013 tropical cyclone Dumile on the seafloor with a large-scale network of 57 broadband OBSs in the southwestern Indian Ocean [8].…”