摘要：

A previous study of inertio–gravity wave motions radiating from a two-dimensional ageostrophic Gaussian jet is extended here to a three-dimensional jet source. Fourier integral solutions of the initial-value problem are obtained in analytic form to facilitate comparison with the previous two-dimensional results. For an initial disturbance elongated along the jet axis, the wave solutions near the midpoint are nearly indistinguishable from those obtained in two dimensions and approach those solutions as the jet increases in length. At locations not symmetric with respect to the longitudinal jet axis, inertio–gravity wave structure departs increasingly from the two-dimensional results. In such cases, the early response is determined by the nearby jet structure and exhibits propagation primarily normal to the jet axis. At later times, however, the response is due to the initial disturbance at other locations along the jet axis and reveals a tendency for propagation parallel to the jet. The mean motions arising from geostrophic adjustment exhibit a localized flow along the initial jet axis with a compensating symmetric, nondivergent horizontal return circulation.

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