Subjective Mapping of Dust-Emission Sources by Using MODIS Imagery
U.S. Army Engineer Research and Development Center (ERDC) Hanover
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Dust storms 5 to 100 km across often originate from multiple dust-emission sources 1 to 10 km across. Remote-sensing-based dust-source identification is a challenge. A previous study developed a subjective approach for mapping dust sources by using enhanced MODIS satellite imagery therefore, this study conducted mapping exercises to assess the reproducibility of this technique amongst multiple analysts and in different regions. Multiple staff members independently analyzed satellite imagery for mappable dust sources for Southwest Asia and the Southwest United States. Mapped points were considered reproducible if the location of dust emission plumes identified by all participants could be constrained to a 10 km buffer. Using this definition, point-source locations were 28 reproducible in Southwest Asia and 85 reproducible in the Southwest United States. Increasing the allotted buffer to 15 km, however, improved results to 71 and 100, respectively. Mapped dust sources for Southwest Asia were compared to geomorphic landform maps. At the 1750,000 map scale, points mapped by all analysts for a single dust plume tended to overlay one landform, while at the 1100,000 map scale, points were strewn across several landforms. Results suggest that the methodology is reproducible for certain applications but that location-uncertainty tolerance affects perceived conclusions.