1ST OBSERVATIONS OF PRECIPITATION WITH A SPATIAL INTERFEROMETER

This paper presents the initial results of a study of precipitation using spatial interferometry (SI) at the MU radar in Japan. On April 30, 1992, data were collected using the VHF Doppler radar at the facility during the passage of a frontal system. A linear variation in the phase was identified in the cross-spectra of t,he returned signal in the Doppler velocity ranges corresponding to contributions from both precipitation and refractive index irregularities of the turbulent air. The portions of the spectra which are attributed to precipitation are broadened by the range of particle sizes and the presence of turbulence. This leads to a larger underestimation in the slope of the phase than would be attributed to turbulent fading alone. The results present the first radar interferometry study of precipitation.