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Cooling of air forced over mountan ranges?

Cooling of air forced over mountan ranges?

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Profile IL

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Message 36957 - Posted: 19 May 2009, 4:01:29 UTC

Hi!

When I watch my screen saver I'm surprised to see that so little of the precipitation is located on the slopes of the major mountain ranges on the globe (Andees, Himalayas, Norwegian coast etc). I thought the cooling of humid sea air that is forced by winds upwards over these mountains generated considerable downpour.

Has the Earth modelled by CPDN no mountains?

Thanks in advance for an explanation!
/IL
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Profile geophi
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Message 36958 - Posted: 19 May 2009, 5:20:54 UTC

Because of the resolution of most of the climate models (hadcm3 and hadsm3), mountains are not very high. Therefore, the vertical motion associated with upslope flow is not extremely strong. The precipitation associated with this upslope may be displaced from where you would expect it in the real world.

hadcm3 and hadsm3 are really global models where the forecasts are used for predicting large scale mean values of temperature and precipitation, not so much on the regional/local scales.

hadam3 and hadam3p are higher resolution models and you would expect the precipitation associated with flow over topography to more closely follow the what is seen in the "real world". In beta testing is a model where a high resolution regional model is nested within a lower resolution global model. Once again in that case, you would expect the upslope precipitation to be more realistic within the nested regional model.
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