At 05:32 AM 1/14/2007, Mike Harris wrote:
>| I don't know much about snow properties at HF, but at Ku-band (13.402
>| GHz, to be specific), the dielectric properties change a great deal
>| with temperature and moisture content. Ice is not particularly lossy
>| or conductive. Water is very much so.
>As far as I am aware snow and ice is transparent to HF.
Especially if it is very cold.
The AMSR-E instrument on Aqua (now in orbit as part of the "A-train"
of earth observing instruments) is also used to evaluate presence of
ice, but it's a microwave radiometer at frequencies >6 GHz.
The now cancelled Hydros mission was to use an L-band radar (1.26,
1.41 GHz) to examine the surface water, including freeze-thaw,
etc. The radar backscatter varies some 5-7 dB between frozen and
A technical paper describing the mission and instrument:
This paper says that the effect of freeze thaw is greater at L-band
frequencies than at higher frequencies that have been used before.
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