Simple way to understand these narrow frequency peaks in recently published "ice shelf singing"?
The wavelengths that travel through the ice have a faster speed of travel, and the physical size of the pressure variations that cause the sound are not 100 meters. It's more like 1 meter, so it's similar to having an oversized speaker cone blasting air waves into the ice, which the ice then transmits to the microphone most clearly at a depth of 1-2 meters.

The best illustration I can find of pressure differentials and resonance modes from wind, of about 5-15 hz are from this 1960's YouTube video:

https://youtu.be/TqTSyFz6DJc?t=176

The frequencies of the speaker cones are guided by air turbulence buffeting from the angles of the snow dunes and the wind, which generate 1/2/3 frequencies, perhaps from 1/2/3 different snow dunes types in the same area, depending on the local dune shapes, and when a storm changes the dune shapes, the frequencies change correspondingly. 



The compressed snow has an elastic property which absorbs higher frequencies at depth and adds higher waves together to form lower waves, so the frequency sounds lower in the ice. 

It's not probable that the frequencies are generated by 100 meter wide diaphragms and pressure differentials because that would correspond to very high dunes and long valleys. the high dunes are not likely, and the wind pressure events in the valleys would not generate major pressure differentials.

If I was a bob moog, and I wanted to copy the physical resonance process of the dunes, It would be a relatively easy synthesizer to design. They have place bass audio cones at different zones of the dune at different times, and measure a 3D map of frequencies and timings from a zone near the artificial sound generator. 

The unclear statements of the article say that:

They measured Perturbation Velocity, a coefficient of flow dynamics for seizmology and of aerodynamics turbulance equations for physics? which kind of perturbation velocity is implied? Where are the equations for perturbation velocity and what a the name of the equations?

Sound propagates through the firn layer, a study which may have already been measured and demonstrated by other snow and ice physicists? Sounds travel through snow, ice and water for different distances. To what distance and efficiency does firn transmit sound? there are graphs for snow acoustics and some of the research is hilarious:

one of the most complex pages of research i have ever seen

from this page: https://www.google.fr/search?q=sound+propagation+in+ice&amp;num=100&amp;source=lnms&amp;tbm=isch&amp;sa=X&amp;ved=0ahUKEwjYptm3s5feAhVLOBoKHa2sBpEQ_AUIDigB&amp;biw=1572&amp;bih=808&amp;dpr=1.5#imgrc=1z-RRNglm0UEGM: