source: TI03-DataExtractor/trunk/web_extras/help_page.html @ 794

Subversion URL: http://proj.badc.rl.ac.uk/svn/ndg/TI03-DataExtractor/trunk/web_extras/help_page.html@794
Revision 794, 1.2 KB checked in by astephen, 13 years ago (diff)

Unstable but latest version with multi-variable support and split hooks
for CDML and CSML.

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1<HTML>
2<HEAD>
3<TITLE>Help page for the Data Extractor</TITLE>
4<HEAD>
5<BODY>
6<H1>Help page for the Data Extractor</H1>
7<H2><A NAME="interpolation">Interpolation note</A></H2>
8<P>The Data Extractor will always interpolate to the coarser grid size because interpolating to a higher resolution will produce a less scientifically valid result.
9
10<P>The algorithm currently used under the Data Extractor is the standard CDAT (Climate Data Analysis Tools) method. This can be described as 'area-weighted' or 'conservative'. That is, cell areas are taken into account, and the target cell value is the average of the overlapping source cells, weighted by the area of overlap.
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12<P>Because it is sometimes important that the regridded data preserve the area average of the original data (e.g., when computing global mean net flux at the top of the atmosphere, or total precipitation and evaporation), this algorithm is often preferred over bilinear, bicubic and other methods. The algorithm will therefore generate smoothing when converting to a coarser grid, but not necessarily when converting to a finer grid.
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14<P>This may be replaced in the near future with the SCRIP regridder.
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16<P><A HREF="#top">Return to top of page</A>
17<P>
18</BODY>
19</HTML>
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