The Los Alamos microwave interferometer

The authors describe a multi-antenna microwave receiver system that monitors an unmodulated beacon transmission from a geosynchronous satellite. The system interferometrically measures temporal fluctuations in tropospheric differential path length, which include fluctuations in precipitable water vapor, over 100to 400-meter baseline lengths. Over 300 s, the system root mean square error (rms) noise is 0.01 radian. These observations will facilitate studies of air parcel motion as the means by which the causative, phase-corrupting atmospheric inhomogeneities drift over the array. The resulting data will be useful for studies of convective boundary layer turbulence, a region difficult to fully access.