An Experimental Study on the Internal Structures of Baroclinic Waves in a Rotating Annulus: Part I. Thermal Structure

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Abstract
Experimental results on the thermal structure of baroclinic waves observed in a rotating fluid annulus, subjected to a horizontal temperature difference, are reported. The main maximum of the amplitude of the wave is observed in the uppermost layer and the secondary maximum is observed in the lowest layer. Because its axis inclines forward (direction of the basic rotation) with height, the latter maximum seems to be associated with a different kind of wave from that of the Eady type which predominates in the uppermost layer. While the wave number is unchanged, the amplitude increases with increasing rotation rate below the level of the main maximum. The phase difference between upper and lower levels decreases with the rotation rate. With a fixed rotation rate and a horizontal temperature difference, different wave numbers may be observed with different temperature distributions such that the distribution for a larger wave number is more or less similar to that for a smaller wave number at a lower rotation rate. The zonal mean temperature distribution in the wave regime is of constant gradients both in the vertical and in the radial directions in the almost entire meridional plane. The zonal mean temperature gradient does not change with the rotation rate and wave number except in the uppermost outer region and in the lowest inner region.