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<br /> <br />!l <br />t <br />l <br />~- <br /> <br />ElcVilUon(lII) <br /> <br />i<I~13.(XWI)1 .1,500 <br />.1,500,000l01- 1,100 <br />.1,100,OlXXlOI'I,71O <br />I!:Il,7iO,OCOOOl -3,000 <br />.3,1XX1.0c0001 . 3,300 <br />ClIJ,lJlloco)()l-3j600 <br />.3,1iOO.OCJ'OJI-l,900 <br /> <br />Figure 1. Map of seeding evaluation area in San Juan Mountains of southwest Colorado. Image <br />represents elevalions above mean sea level in meters, with scale at right. San Juan target areas (west <br />and east) are bounded by red polygon. the Lone Cone and Uncompahgre control areas by cyan and <br />yellow polygons, respectively. WWC silver iodide generator locations are the labeled yellow dots and <br />Snow Telemetry (SNOTEL) measurement sites are the black stars. SNOTEL sites in/near control areas <br />are labeled. <br /> <br />spatial variability than the larger target area. The entire target area was used because WWC <br />asserts that at any time during a "seedablc" stonn, the e",ire target area should be affected by <br />seeding. Not all generators arc operdted during a given point in time. however, based on wind <br />directions and expected transport and dispersion of the seeded plume. While WWC provided <br />data that outlines "sub-areas" within the target that arc assumed to be impacted by a subset of <br />generators, it is beyond the scope of this study to partition areas for more detailed SNODAS <br />dSWE analyses. Moreover, WWC's assertion that the entire target is affected by seeding over <br />the ('''tire stoml event gives motivation to analyze only complete events and the full target area. <br /> <br />It was realized that a considemble contribution to this variable came from snowpack ablation. <br />i.e., melt and sublimation (ice to water vapor). We wish to assess only that part of dSWE <br />cnntributed by snowfall accumulation (natural and seeded), so the ablation contribution should <br />he eliminated. Fortunately, SNODAS also outputs these variables as 24 hour integrations. in the <br />form of melt at snow pack base, blowing snow sublimation. and snowpack sublimation. The <br />latter two variables arc independent. so the SWE losses from both were "added back" to dSWE, <br />just as was done with snowmelt. These adjustments made little difference, except for those days <br />in which there was little total snowfall (Attachment A). On those days, the dSWE could be <br />significantly negative (snowpack SWE loss) and the adjustment (properly) moved it to near zero. <br />This lends confidence that the adjustcd dSWE values were accurate estimates afsnuwfall.e <br />5 <br />