Ground‐based microwave measurements of upper atmospheric water vapor were made during late 1981 at Penn State University using the spectral line decomposition of solar microwave (22.235 GHz) radiation transmitted through the atmosphere. One measurement per day was accomplished by integrating the signal over the daylight hours from sunrise to sunset while accurately tracking the sun with a 2.4 m cassegrain parabola antenna. Preliminary retrievals for the period 13‐21 December 1983 are presented, which show reasonable agreement with recent emission microwave measureme