Atmosphere Ocean Science Friday Seminar

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Stationary inertia-gravity wave frequency spectra generated by geostrophic mean flow refraction

Speaker: Wenjing Dong, CAOS

Location: Online

Date: Friday, April 2, 2021, 4 p.m.

Notes:

The generation of broadband frequency spectra from narrowband wave forcing in geophysical flows remains a conundrum. We investigate this problem by integrating the ray tracing equations for a large number of inertia-gravity wave packets moving through a synthetic, three-dimensional geostrophic mean flow. We find that, in all cases investigated, a stationary inertia-gravity wave frequency spectrum forms, irrespective of the initial frequencies of the waves, and for both stationary and time-dependent mean flows. The frequency spectrum is well represented by a power law, the steepness of which seems to be controlled by the aspect ratio of the mean flow length scales, and to a lesser extent, the time-dependence of the mean flow.