Index: /issm/trunk-jpl/src/m/plot/processdata.py
===================================================================
--- /issm/trunk-jpl/src/m/plot/processdata.py	(revision 17617)
+++ /issm/trunk-jpl/src/m/plot/processdata.py	(revision 17618)
@@ -41,8 +41,8 @@
 	
 	#process NaN's if any
-	nanfill=options.getfieldvalue('nan',0)
+	nanfill=options.getfieldvalue('nan',-999)
 	if npy.any(npy.isnan(data)):
 		data[npy.isnan(data)]=nanfill
-		print "WARNING: nan's treated as zeros by default.  Change using pairoption 'nan',nan_fill_value in plotmodel call"
+		print "WARNING: nan's treated as -999 by default.  Change using pairoption 'nan',nan_fill_value in plotmodel call"
 
 	#non-patch processing