Description: | After the system was installed, the mentor set up the PPI scans with a prescribed
elevation angle of 70 deg. After a couple of weeks of operation we noted that the actual reported
elevation angles in the PPI scan files (i.e. nsadlppiC1.b1) differed from the prescribed
angle.
The PPI scans were initially setup by specifying 8 evenly spaced azimuth angles between 0
to 360deg at an elevation angle of 70 deg. The reported elevation angles at each of these
azimuth angles were:
70.02 70.04 73.25 70.04 70.02 70.00 70.02 70.00
The small deviations on the order of a few hundredths of a degree are not of significant
concern. The one outlier (73.25) is, however, a problem.
We note that the Streamline Pro that is operated at NSA differs from the other DLs that
ARM currently operates in that scanning is limited to +/- 20 from zenith. Thus, the mentor
suspected that the problem might be due to the fact that we were attempting to scan at
the limit of the system's field-of-regard. Accordingly, the PPI elevation angle was changed
from 70 to 75 deg at about 0030 UTC on 20140820. As a result, the elevation angles no
longer contain outliers. Thus, PPI scans for the NSA system will continue to use a 75 deg
elevation angle until further notice. |