Figure 4
From: Phase diagrams of dune shape and orientation depending on sand availability
Transitions in dune shape in the parameter space {θ, N} when the dune develops from a localized sand source.
(a) Growth rate ratio σF/σI and (b) RDP/DP-value in the parameter space {θ, N} of bidirectional wind regimes. The growth rates {σI, σF} are computed with equation (2) using the corresponding dune orientations {αI, αF}, γ = 1.6 and the same {H, W}-values (i.e., the same dune shape). The σI/σF-value depends only on the wind regime. For numerical simulations with low sand availability and localized sand source (Fig. 2b), black and white lines show the zones of the parameter space {θ, N} in which fingers and barchans are observed, respectively. Gray lines indicate the zones for transition in dune shape.
