Mike -
Based on the insights offered by the webpage I mentioned in my previous message, it looks like it may depend to at least some degree on the solar radiation situation at the time. His notes were from the winter of 2002-3. I'll write him and ask what he has observed since then.
Judging by the "irca@xxxxxxxxxxxxxxxx" address, IRCA may have a mailing list - how to subscribe?
Thanks...
Steve
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