Measuring the coherency of microbaroms at long distances for the inversion of stratospheric winds

Abstract

We demonstrate the design of an infrasound network and the associated analysis for measuring the coherency of microbaroms at large distances (10s of km) and inverting for stratospheric winds. We have developed a mathematical framework for the inversion of local stratospheric winds using microbaroms, and found constraints on the optimum sensor network topology. Based on these results, we deployed a prototype sensor network over the winter months (January to March, 2013) that comprised three single-sensor stations, one 30-m and two 1-km arrays with separations between 5 and 70 km. The initial analysis shows periods of very high coherency lasting several hours with tropospheric and low stratospheric celerities. Coherency decreases rapidly with distance and azimuth compared to the direction of propagation of microbaroms. We are exploring topography as the cause of low signal coherency at long distances. Following this pilot study, we are designing a denser sensor network further optimized to capture microbaroms and planning for its deployment and the validation of the inversion scheme using a Doppler Rayleigh Lidar system.