Initiation and Propagation of an Atmospheric Bore in a Numerical Forecast Model: A Comparison with Observations

Abstract

AbstractIn the autumn of 2016, an undular atmospheric bore passed over southern England. Observations at surface sites as the bore passed gave phase speeds of up to 30 m s−1, surface pressure rises of over 1.5 hPa, and abrupt wind direction changes of 90°, followed by slower changes of a further 180°. Use was made of this event, rarely observed in the United Kingdom, to compare surface and satellite observations of the bore with output from the operational Met Office limited-area 1.5-km numerical weather model and to investigate the bore initiation mechanism within the model. Although the model had timing errors of over an hour and orientation errors of the bore, the bore propagation was simulated fairly well, giving similar bore phase speeds and decay times. There was also a reasonable correlation between surface and satellite observations and the model. One significant difference was the longer bore wavelength in the model simulation.