P1.35
Predicting precipitation in a mesoscale mountain range
Haraldur �lafsson, University of Iceland, IS 150 Reykjav�k, Iceland; and �. R�gnvaldsson
Quantitative precipitation forecasting in meso-scale mountains that are not resolved in NWP models is not an easy task. In order to develop some guidelines, observations in SW-Iceland are studied to investigate the connection between precipitation in a 700 m high mountain ridge and precipitation in an airmass that is not influenced by the mountain ridge. A stong correlation is found between the difference in precipitation in the mountains and in the lowland and the low level wind The connection between these factors is described by the M-curve. At very low wind speeds, the mean precipitation in the mountain is similar to the mean precipitation in the lowland. As the low level winds increase and the flow enters the �flow-over' regime, so does the ratio of precipitation in the mountains to precipitation in the lowland. For a range of higher wind speeds, the ratio of precipitation in the mountains to precipitation in the lowland remains close to constant, while for wind speeds of 15-18 m/s, this ratio increases rapidly. At winds greater than 20 m/s the ratio drops rapidly again.
Poster Session 1, Conference Posters
Monday, 1 August 2005, 5:30 PM-7:00 PM, Regency Ballroom
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