I have a shp file with the location (lat, lon) of lightning spatial distribution. I want to produce a density map of lightning occurrence per square KM. I used density point function and I don't know how to transform the output in square KM. My map's unit is kilometer I should use 1 Km radius? I'm using ArcGis 9,3 I appreciate any answer.
Choose square kilometres for the area units parameter in the density tool. Then your result raster is lightnig per square kilometer. You do not have to transform anything.
The search radius is independent of the area units parameter. Larger values of the radius parameter produce a smoother, more generalized density raster. Smaller values produce a raster that shows more detail.