Print Email Facebook Twitter The life cycle of a sudden stratospheric warming from infrasonic ambient noise observations Title The life cycle of a sudden stratospheric warming from infrasonic ambient noise observations Author Smets, P.S.M. Evers, L.G. Faculty Civil Engineering and Geosciences Department Geoscience & Engineering Date 2014-11-13 Abstract A method is presented to study the life cycle of a SSW using infrasonic ambient noise observations. The potential of infrasound is shown to provide the missing observations required by numerical weather prediction to better resolve the upper atmosphere. The 2009 major SSW is reanalyzed using the Evers and Siegmund (2009) data set. Microbarom observations are evaluated to identify detections that cannot be explained by the analysis of the European Centre for Medium-Range Weather Forecasts. Identified differences can be related to either the altitude limit of the analysis, not resolving thermospheric ducts, or to an actual error in the analysis. Therefore, a first-order model is used to relate observations with the analysis, existing of the Waxler et al. (2007) microbarom source model, including bathymetry to allow column resonances, and an atmospheric propagation model using 3-D ray tracing. Daily normalized spectral powers are proposed to distinguish stratospheric from thermospheric return height, based on the different signature of solar tidal amplitude fluctuations. It is shown that a SSW is not a smooth event as following from the analysis but a series of abrupt changes with a period of 10 to 16 days, increasing in intensity and duration. This is in agreement with the wave period of Rossby waves, interacting with the stratospheric circumpolar vortex. The type of vortex disturbance, split or reversal, can be deduced from the combined effect of the change in back-azimuth direction, solar tidal signature type, and/or phase variation of the amplitude variation of the observed microbaroms. Subject infrasoundstratospheric warmingmicrobarom source modelingpropagation modelingsolar tides To reference this document use: http://resolver.tudelft.nl/uuid:146e54ec-4e1b-4caa-a6b8-4458b34dcb53 DOI https://doi.org/10.1002/2014JD021905 Publisher American Geophysical Union Embargo date 2015-05-13 ISSN 2169-897X Source Journal of Geophysical Research: Atmospheres, 119 (21), 2014 Part of collection Institutional Repository Document type journal article Rights © 2014 American Geophysical Union Files PDF Evers_2014.pdf 4.56 MB Close viewer /islandora/object/uuid:146e54ec-4e1b-4caa-a6b8-4458b34dcb53/datastream/OBJ/view