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capri:concept:spatyields [2011/04/11 09:37] gochtcapri:concept:spatyields [2011/04/11 09:37] – external edit 127.0.0.1
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 +<H2><a class="intext" HREF="/dokuwiki/doku.php?id=capri:concept:spatialdownscaling">Agricultural land use and environmental indicators at 1x1 km grid resolution</A><BR> - Yields and Irrigation share</H2>
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 +<hr style="color: 'blue'; height: '2'; text-align: 'left';">
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 +Main Contributors: Wolfgang Britz and Gunter Wriedt<BR>
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 +GIS processing of MARS yields: Renate Koble and Giulio Marchi
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 +<hr style="color: 'blue'; height: '2'; text-align: 'left';">
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 +<P>The <B>crop yields</B> are estimated based on estimates of water limited and non-water limited yields, courtesy of the JRC's
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 +<a class="intext" HREF="http://www.marsop.info/scripts/mars.exe?page=bg">MARS</a> project, and per grid cell reported as the
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 +average of the water limited yield times unity minus the estimated irrigation share for that crop in the pixel cluster plus the non-water
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 +limited yields times the estimated irrigation share. A statistical estimator ensures that the average yields as reported in regional agricultural statistics from Eurostat are recovered.</P>
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 +<a href="images\IRR.jpg"><img style="text-decoration: none;border: none;color: white;" src="images\IRR.jpg" width="400px"/></a>
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 +<P>The <B>irrigation shares</B> and yields per crop and 1x1 km cell cluster are statistically estimated
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 + based on a Highest Posterior Density estimator, which ensures the following conditions:</P>
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 +<UL>
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 +    <LI><P>The total irrigated area at NUTSIII/NUTSII region reported in the 1999 Farm Structure Survey is recovered</P></LI>
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 +    <LI><P>The area weighted average yield per 1x1 km grid cell and crop is identical to the yield found in regional statistics</P></LI>
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 +    <LI><P>Average yield per 1x1 km grid cell and crop are a weighted average of the non-irrigated and irrigated potential yields from MARS, multiplied with an identical scaling factor</P></LI>
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 +</UL>
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 +<P>Given the fact that there are more variables to estimate (irrigation shares per crop and <A HREF="/dokuwiki/doku.php?id=capri:concept:HSMU">HSMU</A>, scaling factors for yields per region), the statistical estimator picks the most probable
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 +combination based on minimizing deviations from given information:</P>
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 +<UL>
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 +   <LI><P>The reported or average irrigation shares at NUTS II level for selected crops. Where no shares had been reported, those had been estimated based on regression models based
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 +    the reported average irrigation shares, and using climate data as explanatory variables.</P></LI>
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 +   <LI><P>The average irrigation shares per HSMU, defined from the global irrigation map of FAO</P></LI>
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 +   <LI><P>A preferred scaling factor of unity for the crop yields</P></LI>
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 +</UL>
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 +<hr style="color: 'blue'; height: '2'; text-align: 'left';">
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 +<H3>More information</H3>
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 +<P class="pubparagraph"><span class="pubAuthor">Britz W. and Wriedt G.</span>:<BR>
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 +<I><a HREF="..\docs\yields.pdf" class="intext">Pan-European Estimation of crop specific yields and irrigation shares at 1x1 km grid, JRC, 2007 (pdf, foils)</a></I></p>
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 +<BR>
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 +<font size=1>Last Updated:Tuesday, October 28, 2008
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