Boundary-layer studies with an S-band radar

Recently, the NOAA Environmental Technology Laboratory developed a 2875-MHz (S-band) vertical profiler with extended dynamic range for cloud and precipitations studies. The extended dynamic range is achieved by alternating the radar between two operating modes: one where pulse coding boosts the average signal power and another where a microwave coupler decreases the signal intensity by a known amount before the signal enters the receiver. The increased sensitivity provided by pulse coding allows the radar to detect clear-air echoes resulting from refractive index turbulence. This additional capability makes the radar a valuable tool for investigating the vertical structure of the planetary boundary layer. As compared to the 915-MHz boundary layer radar/wind profiler, for example, the S-band radar has a narrower beam, finer vertical resolution, and reduced susceptibility to stationary clutter, although its sensitivity to insects and clouds is enhanced. In this paper we demonstrate the clear-air profiling capability of the S-band radar using examples collected in the central valley of California during the summer of 2000.