Numerical simulation of the large-amplitude mesoscale gravity-wave event of 15 December 1987 in the central United States

It is found that the model can successfully simulate mesoscale gravity waves and can capture many aspects of an observed wave event. For this case the model mesoscale gravity waves arose, matured, and decayed in the same regions as those observed and had similar timing and amplitudes. Model wave speeds, however, were 1-1.8 times those observed. The model output showed that although a good wave duct covered the wave activity area, the model waves were maintained and amplified by wave-CISK processes. These waves appeared to be generated by convection of mesoscale extent above a stable duct. This convection moved with the waves and was associated with steering levels. Model sensitivity experiments showed that 1) the model mesoscale gravity waves do not stem from initial data imbalances, 2) model mesoscale gravity-wave development does not occur when latent heating is removed, 34) model mesoscale gravity-wave production is not necessarily limited to the early hours of a simulation, and 4) model mesoscale gravity waves can be produced using grid sizes up to 45km. -from Authors