Séminaire
East coast low (ECL) events are a major source of precipitation on the eastern Australian seaboard. In fact, it is not uncommon for a location to receive a significant portion of its average yearly rainfall in one to two days from an ECL event. Because of this, developing ways to accurately simulate ECL events and compare modelled extreme precipitation to observations is an important and challenging goal. We investigate how the Weather Research and Forecasting (WRF) model simulates extreme precipitation for ECL events with an emphasis on understanding the connection to model physics. We focus on the Newcastle ECL of 2007, which was one of the most powerful ECLs in recent memory, with high precipitation and strong winds in the Newcastle area. We examine the sensitivity of precipitation extremes to microphysical schemes, radiation schemes, boundary and surface layer physics, and cumulus parameterizations. Using the Bureau of Meteorology rain gauge network, we compare to hourly model precipitation fields using an ensemble based approach. This comparison shows that WRF, when appropriately configured, does simulate the extreme precipitation well, although there are important differences between the physics parameterizations. The underlying mechanisms controlling these differences in modelled extreme precipitation will also be discussed.
MP Lefebvre (0144272799)