<div class="gmail_quote">On Feb 20, 2008 9:11 AM, Jennifer Adams <<a href="mailto:jma@cola.iges.org">jma@cola.iges.org</a>> wrote:<br>
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<div style="WORD-WRAP: break-word">Hei, Stefan --
<div>The skip() function in GrADS will degrade the resolution in the way you suggest. Something like:</div>
<div> ga-> d skip(var,2,2)</div>
<div>Since you you are using GrADS 2.0, the lterp() function is now built in and will allow you to interpolate from one grid to another. The algorithm in lterp is bi-linear interpolation from the nearest neighbors, so if you define your destination grid to have points at the centers of the 2x2 grid areas in your source data, then lterp will do the same thing as aave(). </div>
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<div>I am confused. Is the algorithm in lterp() linear interpolation or does it switch to coservative box-averaging when coarsening the grid? This is important to avoid aliasing.</div>
<div> </div>
<div> Arlindo</div>
<div> </div></div>-- <br>Arlindo da Silva<br><a href="mailto:dasilva@alum.mit.edu">dasilva@alum.mit.edu</a>