Post processing: Applying a simple exponentially decaying weighting of average fluxes over a domain

All, I am simulating an optical biosensor probing a 2D domain at an interface. After I have a solution andmove to postprocessing I want to mimick the expeonetial decay (penetration depth ~300nm) in senstitvty with distance from the optical interface using a simple exponentially weighting of the average fluxes over a domain. I want to plot this flux in time since the solution includes timesetepping. I can do it by creating many seperate component couplings (point averages) and then adding a weiging factor term to each and then average them all using a sum of all expression in the Global-line graph readout. I can easily apply x,y dependent functions to regions of components using the funtions(f(x)) tab when definging my component model so is there a simialr way to apply such expressions when plotting a line graph in postrocessed . Many thanks for thinking on this, John.