Bin Cheng visited the Mathematical Sciences Institute at the University of Cambridge on Thursday 30 May to give a talk in the Applied and Computational Analysis Series. The title of the talk was “Analysis of some nonlinear PDEs from multi-scale geophysical applications“. The talk was on PDE systems from geophysical applications with multiple time scales, in which linear skew-selfadjoint operators of size 1/epsilon give rise to highly oscillatory solutions. Analysis is performed in justifying the limiting dynamics as epsilon goes to zero; furthermore, the analysis yields estimates on the difference between the multiscale solution and the limiting solution. The talk introduced a simple yet effective time-averaging technique which is especially useful in general domains where Fourier analysis is not applicable.