I agree with Robin hoods assessment in part, but would like to add or question if there is shielding on the mic or recording media? Is the period/frequency affected by time of day/location position of sun or any other weather phenomenon like storms high pressure low pressure air current channel etc etc?
Has the sound been parsed by AI with timestamp meta data against other known time stamped databases in order to determine any potential sound origins? If this is really Sandia... you do have that ability yeah?
But this is all BS.
The real 2 issues that should be talked about are;
a. wtf. Your 'researchers' wear tie dye and random overalls with semi hard baseball like hats in actual field work??? Or is this music video or burner party?
b. Sound shmound. What is going on with the clouds in the photos? You aren't seriously going to tell me that the clouds are normal, not cgi, or don't have something a little odd going on ? I've seen same and photo them. they form oddly, progress unlike standard stratocirrus clouds and seem to be much much lower in cumulus territory then head in similar wedge from origin vectors but unscroll form in face, figure, letters. What is all that?