A simple model of aeolian megaripples

We discuss a simple mathematical model for the formation of aeolian megaripples. The main idea is that the sediment consists of a mixture of grains with two different sizes and that the wind is not strong enough to cause the coarse fraction to saltate. Linear stability analysis indicates the presence of two maxima in the growth rate of the unstable modes. The gravest mode corresponds to megaripples and the other to “standard” aeolian ripples.