Effects of rotation on fronts of density currents

The effects of background rotation with angular velocity f/2 are studied for buoyancy driven currents of initial height h₀ whose density exceeds by Δρ the ambient value of ρ₀. Our aim is to find how viscous density currents adjust in time under effects of background rotation focusing on time evolution of fronts of density currents. Rotation reduces the front velocity, U(F)/(f) = F(ft)U(F)/⁰, of the density current which is compared to a non-rotating case, U(F)/⁰, by the function F(ft) where F → 1 as ft → 0 and F → 0 as ft → ∞. When the parameter μ = ft becomes of order one, there is a transition to the geostrophic asymptotic regime. We present numerical results for the transition curve for the density current front radial position for axisymmetric density currents on a rigid surface in a rotating frame. The transition is from a non-rotating power law to a long-time solution. The results of laboratory experiments are found to agree with the results of numerical simulations. (C) 2000 Published by Elsevier Science B.V.