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 Post subject: Lakes
PostPosted: Fri Mar 28, 2014 5:35 pm 
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Joined: Thu Mar 27, 2014 5:03 pm
Posts: 67
As PRECIS is an atmosphere and land surface model, it requires sea surface temperatures (SSTS) and sea ice information as input. This data typically comes from the driving global model. One issue in PRECIS is how to assign SSTs inland water grid boxes that are not represented in the global model. In this situation temperatures are assigned from the nearest available data point, these are often unrealistic and can cause locally an un-realistic simulation, in some cases can even cause the RCM to go unstable.


Inland water points can be converted to land using the PRECIS user interface:

Clicking on the "Edit Region" button in the main PRECIS interface shows the generated land-sea mask for the region with a high resolution map overlaid. A second "Point Details" window showing information on coordinates, orography and vegetation is also displayed. Land points are shown in green, and sea points in blue. The rim is shown in darker blue and green. The height of the point is indicated by its colour: the darker the box, the higher the grid point.

We recommend that, all lakes that have a high altitude (height 500m or greater), high latitude (latitudes greater than 55?N/S) or are a significant distance from the sea (200 km or greater) should be converted to land points by clicking on the grid box with the left hand mouse button. This can be done in the rim of your region too. For all other lakes (for which the inland water area has surface data provided), click on the grid box using the left mouse button while holding the control button on the keyboard. The points will turn cyan blue. Only inland water points can be altered this way.

For more information on configuring a region see chapter 5.2.2 of the PRECIS Technical Manual.

_________________
Simon Tucker
Met Office Hadley Centre


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 Post subject: Re: Lakes
PostPosted: Wed Feb 18, 2015 5:35 pm 
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Joined: Thu Feb 06, 2014 12:29 pm
Posts: 118
Please see this document
http://www.metoffice.gov.uk/media/pdf/b/i/Criteria-inland-water.pdf
for more information and instructions.
Thanks
David


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