Jmnt. Gray et al., THE EFFECT OF CHANGE IN THERMAL-PROPERTIES ON THE PROPAGATION OF A PERIODIC THERMAL-WAVE - APPLICATION TO A SNOW-BURIED ROCKY OUTCROP, J GEO R-SOL, 100(B8), 1995, pp. 15267-15279
The propagation of a periodic thermal wave into snow is significantly
altered by the presense of a shallow rock interface because of the lar
ge difference in thermal properties of the two media. The temperature
distribution is modeled using classical heat conduction equations subj
ect to a periodic diurnal or seasonal surface heat flux condition, jum
p conditions at the interface, and insulating conditions in the far-fi
eld. The natural length scale (skin depth) over which order unity chan
ges in temperature occur is proportional to the square root of the tim
escale of the surface temperature variations. If the interface lies cl
ose to or within the skin depth then large temperature gradients can b
e sustained in the snow before temperature oscillations are forced thr
ough to the underlying rock. These features are explained by an analyt
ic one-dimensional periodic solution. A numerical algorithm is constru
cted to solve for the temperature around plane two-dimensional rock ge
ometries. The results show that during a period of atmospheric cooling
the presence of a buried rocky outcrop increases the snow temperature
and temperature gradients simultaneously to produce very favorable co
nditions for crystal growth and avalanche formation.