I was sent these images last night and decided to investigate them. I have spoken to a friend who's son is serving in the US armed forces and they are aware of this phenomenon also.
There are many references to the Kopp-Etchells effect on the internet and it appears to be a common occurance in sandy environments.
Here is a more in-depth article at
www.military.com
I thought this might be of interest to some of the aviation folk on IIS.