Attenuation of Wind Noise by Seismic Surface Arrays and Nodes

Abstract

Summary Land seismic recordings are susceptible to wind noise which can be effectively attenuated by surface arrays. Seismic nodes and point-receiver acquisition methods have to rely on different noise attenuation methods. We analyze wind noise recorded by a surface array and a shallow vertical array. We show that the wind noise consists of interfering Rayleigh wave modes with a wavelength less than 1 meter for frequencies above 40 Hz. We also show that the wind noise measured at an interval over 1 m appears as incoherent noise whose amplitude in n summed traces reduces by 1/√n. We propose an empirical model for wind noise spectrum as function of wind speed and depth and this model to both data-sets. The model shows that the wind noise spectrum increases by the wind speed to the power of 1.8. Furthermore we show that at this location, the attenuation of wind noise for frequencies between 40 and 100 Hz by a n geophone surface array is equal to a single geophone buried at depth z=√n/20. A geophone or seismic node buried at 20 cm depth is expected to attenuate wind noise by 12 dB, similar to a 16 element surface array.