Description: | Starting Dec 16th the Skyrad PIR1 and PIR2 (down_long_hemispheric)started differing by
greater than 30W/m2 at times. This is much greater than expected for these instruments
(typical is <10-15 W/m2). NSA OMIS reports and observer comments reveal that PM
periodically clean the snow from the IRT and ventilator fans on Skyrad and Gndrad. In the case of
the Skyrad PIRs, one lies in the wind shadow of the other and builds up more snow which is
periodically cleaned out and then builds up again causing the PIR1 PIR2 discrepancies.
Disregard down_long_hemispheric during this time period. However, data suggests PIR2 is
most likely at fault - potentially use PIR1 data during this time period. |