  In this paper, the Precipitable Water Vapor (PWV) content of the atmosphere
is derived using the Global Positioning System (GPS) signal delays. The PWV
values from GPS are calculated at different elevation cut-off angles. It was
found that the significant range of elevation cut-off angles is from 5 degrees
to 50 degrees. The PWV values calculated from GPS using varying cut-off angles
from this range were then compared to the PWV values calculated using the
radiosonde data. The correlation coefficient and the Root Mean Square (RMS)
error between the GPS and radiosonde derived PWV decreases with the increasing
cut-off angle and the distance between the two. The seasonal parameters also
effect the relation between the two.
