Description: | A malfunction occurred with the AOS surface ozone instrument during the period 990507 1556
GMT to 990514 1445 GMT. The instrument reported an ozone concentration of 9.91e-01 ppm
(991 ppb) continuously during this time. Quality checking of the data the following week
revealed that the problem began at about the time weekly maintenance check was made on
Friday. The problem continued until the next weekly maintenance check was done. Site Ops
was notified by the mentor of the problem on Friday, 5/14/99, and a technician was sent
to inspect the system. No switches on the instrument front panel were found in the wrong
position (for example, if the instrument was inadvertantly left in a calibration mode).
By the time the technician arrived at the trailer, the instrument appeared to be working
correctly. No explanation is given as to why these erroneous values were being
generated by the ozone instrument, except that possibly it locked up with the throwing of the
weekly preventative maintenance switch and this problem was not corrected until the same
switch was thrown the following week. |