Thursday, 14 January 2016
Concentric gravity waves (CGWs) are atmospheric phenomena with ring-shape perturbations originating from the troposphere. They can propagate up to the ionosphere and thermosphere and dynamically couple the lower and upper atmosphere. In this study we developed a novel ring detection algorithm to extract CGWs from the Atmosphere Infrared Sounder (AIRS) radiance data and the European Center for Medium-Range Weather Forecasting (ECMWF) analysis temperature in the stratosphere to produce the first global maps of such phenomena. The algorithm is capable of estimating wave amplitude, wavelength, propagation direction, and source location. Both AIRS and ECMWF data show a significant diurnal variation in wave propagation direction and generation, in addition to strong seasonal variations in wavelength and amplitude. Occurrence of these ring waves is associated not only with tropical deep convections but also with summertime midlatitude convection, wintertime extratropical jets, and pointy topography such as islands. The high-resolution ECMWF analysis data capture most of the CGW features, but the wave amplitude is significantly weaker than AIRS observations, showing few convectively generated CGWs.
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