Given the clear skies that have predominated during this period, I think we can eliminate cloud and precipitation influences from the hypothesis list. I also believe there are no problems with the sensor, so I think we're looking at an example of local microclimatic effects due either to terrain or vegetation shading.
On a meteorological scale of 1-10, this rates about a zero, but it's still a learning opportunity.
So Jim, just thinking about this, is this a siting problem? e.g. a shadow covering the area during that time frame? Do you have pics during that time frame of the sensor? it would also be helpful to see the data "zoomed in" eg overlay each day on the same graph +/- a couple hours of the event. Note this is coming from a engineer not a scientist!
ReplyDeleteSomebody needs to go there and look at that thing during that time. If it is caused by a shadow of some sort I would expect that the onset would change ever so slightly in time due to the slightly different position of the sun each day. I suspect that you would need to compare the onset times at different weeks to see the difference. This would be an interesting problem to give to a couple of students to work out. Extra credit.
ReplyDeleteFrom my limited perspective, I wonder if a sloshing of air around is responsible. Is there a wind graph for this site? It would be interesting to see if the winds are mostly calm during these events, or if there is a direction shift.
ReplyDeleteMy bet is on a tree shadow.
ReplyDeleteI had a meeting at Alta today and was at the site and like an idiot didn't take pictures! Yup, one rung below Homer Simpson.
ReplyDeleteWhy is that notch always at the hour mark?
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