I did like the CHM scheme but then blue is my favorite color so I'm biased.
An obvious alternative, given the subject matter here, would be to use the ROYG range of the spectrum for fading. Something like
(EDIT: ok this works better as an image)
Colors I used are #800000, #a02000, #c04000, #e06000, #ff8000, #ffaa00, #ffd400, #ffff00, #c0e000, #80c000, #40a000, #008000