Extended Abstract (408K)6.7
High Resolution Modelling of Orographic Rainfall
Humphrey W. Lean, Met Office, Reading, Berks., United Kingdom; and P. A. Clark
The Met Office is currently developing high resolution (order 1km gridlength) versions of its Unified Model for future operational NWP use. One of the potential advantages of high resolution models is improved handling of orographic rainfall. The focus of this work is on the seeder-feeder effect which is thought to be responsible for much of the orographic rainfall in the UK. Results are presented from an idealised seeder-feeder model and scale analysis. This analysis indicates how the behaviour of orographic enhancement depends on the relationship between the length scale of the orography and a characteristic length scale of the enhancement process. Data will also be shown from running case studies with the Unified Model at various resolutions. Results from a non-hydrostatic version of the model are compared with those from a hydrostatic version. In addition, results highlight the complications introduced by ice processes when the melting level is within the feeder cloud.
Session 6, Continued
Wednesday, 25 June 2003, 10:15 AM-11:15 AM
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