search for: chloroa

Hello All I am currently looking at spatial data - Chorophyll A concentration in sea water over a wide geographic area. These data are used to determine the location of ocean fronts and hence where tuna are located. A front is identified by a steep gradient in the change in chloroA concentration. I have been looking at these data qualitatively using persp, contour, and image but would like to determine a metric for the rate of change in concentration between evenly spaced cells - essentially determine the maximum gradient of the surface at each point. It would be preferable t...