High-Resolution Modelling of the Morning Glory

The morning glory is a low-level roll cloud or series of roll clouds that occurs regularly during the spring months over the southern part of the Gulf of Carpentaria and the surrounding seaboard, in northern Australia. Cape York Peninsula provides a unique environment for the generation of this cloud line, as its tapering width and north-south alignment allows the collision of the east and west coast seabreezes to occur. It is believed that a southwestward propagating bore or solitary wave train which constitutes the morning glory is generated from this collision. Such features have been observed in field experiments, but so far have not been adequately simulated in numerical models.

The generation and dynamics of the morning glory cloud line over northern Australia is investigated in detail using the Clark-Hall cloud-scale model. The work presented here follows a similar line to several previous studies, and considers a two-dimensional cross-section of Cape York Peninsula. However, unlike previous studies the model is nonhydrostatic and the horizontal resolution is about an order of magnitude better. The model explicitly resolves the seabreeze collision and the subsequent generation of a propagating bore.