Atmospheric Specifications for Infrasound Studies: 1. Operational Analyses

Abstract Operational analysis products issued by weather services are needed for the Comprehensive Nuclear‐Test‐Ban Treaty's (CTBT) infrasound monitoring activities. They provide atmospheric specifications as high as 80 km altitude. They are used to feed propagation simulations designed to characterize sources of interest. Acoustic waveguides for long‐range infrasound propagation form in the lower and middle atmosphere between approximately 10 and 110 km. Analysis products have biases in the stratosphere and above due to the decreasing amount of operational observations available for data assimilation systems. We investigate differences between two state‐of‐the‐art analysis products, namely that of the Integrated Forecasting System, IFS, from the European Center for Medium‐range Weather Forecast and that of the ICOsahedral Non‐hydrostatic model, ICON, from the German Weather Service. We compare their differing predictions of acoustic waveguides across the International Monitoring System (IMS) of the CTBT. We demonstrate significant differences in prediction of waveguide strength in the equatorial region, related to different amplitudes of the westerly phase of the Semi‐Annual Oscillation. Waveguide occurrence predictions can differ by up to 40 across the IMS, in the meridional and zonal directions. We quantify biases with respect to LiDAR wind and temperature observations at three sites. We demonstrate biases of up to 40 and 60 in terms of waveguide occurrence prediction for ICON and IFS, respectively, using the Institute for Atmospheric Physics's LiDAR simultaneous wind and temperature observations. We stress the added‐value for more high‐resolution measurements in the tropical region where operational products strongly disagree at altitudes that matter for infrasound propagation.