During the period referenced, the ground PIR was noisy in comparison to the sky PIR data.
At the end of November, the noise increased to roughly 10 W/m2 from peak to peak. After
12/23/98, the noise decreased in amplitude but still had noisy patterns.
On 01/17-18/99, there was an increase again in the noise level (4 GMT 01/17 - 5 GMT
01/18). During this period the gndrad IRT data also exhibited noise patterns (the IRT was not
In February, the instrument exhibited large noise variations again. On 02/16, a wiring
problem was corrected and the noise dropped back to 1-5 W/m2. However, the noise levels
began to increase again.