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capri:concept:spatyields [2011/04/11 12:37]
gocht
capri:concept:spatyields [2011/04/11 12:37] (current)
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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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 +<div style="​float:​right;​padding:​20px;​padding-right:​0px">​
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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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 +</​div>​
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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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