I have run into this problem myself. Unfortunately, Arc does not support any "greater than", "less than" function in its neighborhood analysis with regard to the center cell or neighborhood applied. One way you can get around this is by running "Local Elevation Percentile" in the open source TAS GIS by John Lindsay at http://www.uoguelph.ca/~hydrogeo/software.html. And then export it as a txt file for import back into Arc. Lindsay has also put together a new GIS program called "Whitebox", though it does not process for elevation percentile as far as I can tell' TAS is the program you need. See: Lindsay, John B. 2005. The Terrain Analysis System: a tool for hydro-geomorphic applications. Hydrological Processes 19, no. 5 (3): 1123-1130. doi:10.1002/hyp.5818. I have also processed for elevation percentile for landform extraction in GeoMedia Professional using their Grid extention, but this was a custom command written by B. Klingseisen, see: Klingseisen, B., G. Metternicht, and G. Paulus. 2008. Geomorphometric landscape analysis using a semi-automated GIS-approach. Environmental Modelling & Software 23, no. 1: 109�??121. I believe TAS is your best bet for automated processing, until ESRI decides to make more robust neighborhood statistical analysis. I hope this helps, Williams Gandy Division of Stormwater City of Winston-Salem, NC http://ci.winston-salem.nc.us/Home/Departments/Stormwater
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