Description: | On clear days there is a dip in the data (all channels) at solar noon that is more
pronounced during the winter months. While we currently don't know the cause of this dip, we
believe it is related to reflections off the tower pole. The working theory says at solar
noon the north-south crossbar shades the tower pole cutting off reflections into the
detector. If true, this means data on either side of the dip are being enhanced by
reflections and the data within the dip are actually "correct." An experiment is being planned
for next fall that will wrap the upper portion of the tower in a non-reflecting cloth.
This should determine if the dip is related to reflections from the tower pole.
Since at this point we don't know if the dip consists of bad or good data, users should be
aware there is a problem and treat all the data as suspect. It should noted that the
magnitude of the problem is relatively small, likely no greater than 2.5%, so the dataset
as whole is probably still useful as is for most users. |