Reply

make the point that more than one mechanism islikely to be involved in the production of polar cap density patches. While we would readily agree with this, we feel REA misinterpret important aspects of the mechanism we proposed [Lockwood and Carlson, 1992], and this leads them to dismiss it as a major source of patches. REA argue that there are insufficient pre-existing radients in the plasma density outside the polar cap for the model we propose to explain patch production. This is partly because they assume that our mechanism requires the day/night terminator to lie in a specific position relative to the equator-ward edge of the convection pattern which is rarely achieved (and does not apply to the three examples we presented). We do not agree with their argument for three reasons: 1. In a true time-dependent model, such as that w