The bottom Ekman layer and the apparent violation of the maximum principle |
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| Authors: | Hezi Gildor |
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| Institution: | 1. Department of Environmental Sciences , Weizmann Institute , Rehovot, Israel hezi.gildor@weizmann.ac.il |
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| Abstract: | The solution for the bottom Ekman layer has a somewhat counter intuitive character, which seems to violate the maximum principle: at a certain level the velocity within the Ekman layer is higher than the velocity in the geostrophic layer above. I explain this character by looking at an analogous problem in an inertial frame of reference and show that it is the result of observing the flow from a rotating frame of reference (i.e. within a system that is not in steady state). The flow in the bottom Ekman layer is a superposition of the flow that results from the force exerted on the fluid by the rotating Earth and of the flow that results from the pressure-gradient term. Therefore, at a certain level the speed is higher than the speed of the geostrophic layer above which results from the pressure gradient alone. |
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| Keywords: | Ekman layer Maximum principle Boundary layer |
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