| Description: | The tracker has a problem in tracking the sun continuously in the southern hemisphere and
close to the equator. This happened between the March equinox and September equinox
around solar noon. Affected hours are between 00:00 to 1:00 each day for the specified time
range.
Note: This will likely occur again in 2013 between March equinox and September equinox
around solar noon.
Note2: The tracker tracking being off only affects data when there is direct sun, i.e.
when the sun is not blocked by cloud. Thus in the tropics much of this data are not
inherently "bad" plus only the direct and diffuse are "bad" when there's direct sun present. The
QCRad has a test for "tracker off" that detects the tracker not shading the diffuse
instrument and the NIP not being aimed at the sun when the sun is not blocked by cloud. Thus
the ARM recommended measure QCRad data set will catch most of these "bad" data and set the
values to "-9999.9" when the sun is not blocked by cloud, and leave the data that is OK
when the sun is blocked by cloud (unless that data fails some other testing of course). |