Laserfiche WebLink
MEMO -TASK 89.1 <br />Figure 1 shows the mean multi-temporal NDVI values obtained from reference samples in the Larimer <br />County pilot study area. NDVI, an index used to measure and monitor plant growth, vegetation cover, and <br />biomass production from multi-spectral satellite data, is described in more detail in Section 5.2 of this <br />report. From Figure 1 it is evident that all the dates selected, including the ones in transition periods at <br />the beginning and end of the crop season, contribute considerably at one point to the discrimination of <br />crops. For instance, corn and sugar beets have very similar NDVI values for the period April through <br />August, but they are different and can be discriminated if September NDVI is used in the classification. <br />This is because the sugar beet fields are mostly green during late September but much of the corn (for <br />silage) in the pilot area was already harvested by the same date. <br />Multi-temporal NDVI Trend of Selected Crops <br />190 <br />180 <br />170 tAlfalfa <br />°<. <br />160 y~ f Barley <br />~ Corn <br />z 150 Irrigated Pasture <br />~ ~ ',~ ~11~Irrigated Wheat <br />a`°i 140 ~ flrrigated Oats/Hay <br />~ +Pinto Beans <br />130 Sugar Beets <br />120 <br />110 <br />100 <br />Apr 26 May 12 Jun 05 Jul 07 Aug 24 Sep 25 Nov 4 <br />Landsat Acquisition Date <br />Figure 1: Multi-temporal NDVI signatures of selected crops obtained from reference samples in the <br />Larimer County pilot study area <br />4. Recommended multi-date satellite data acquisition <br />We are recommending multi-date Landsat images for irrigated lands classification and crop type <br />discrimination in the SPDSS project. One important factor is that the cost of Landsat data is now quite <br />affordable. Since 1999, Landsat products have been distributed at "the Cost of Fulfilling User Requests", <br />known as the COFUR price, of approximately $600 per scene. This significant price reduction, from <br />approximately $4000 per scene, allows renewed use of Landsat data in academic institutions for scientific <br />research, and has stimulated the use ofmulti-spectral imagery in a variety of applications. <br />Based on an assessment of Landsat frame 33/32 and taking into consideration cloud cover limitations, we <br />have prepared a summary list of recommended 2001 Landsat satellite images for acquisition (Table 3). <br />This list includes a total of 20 additional images to the seven images already acquired for frame 33/32, or <br />a total of five images per frame. As described in the previous section, the analysis of frame 33/32 <br />indicated that additional image dates significantly improved irrigated lands and crop discrimination. <br />Page 5 of 13 ~,~/versfde TecAnafagy, lnc. <br />W:rler Resources Frr~mec.•rng ,end L'nr+surlrn2 <br />