Cross-calibration of Zenith Pointing Cloud Radar with Scanning Cloud Radar

The Atmospheric Radiation Measurement (ARM) Climate Research Facility replaced the esteemed vertically pointing Millimeter Wave Cloud Radars (MMCR) with the new Ka-band ARM zenith radars (KAZRs). In addition, ARM will deploy Ka/W-band scanning ARM cloud radars (Ka/W-SACRs) at its Southern Great Plains site (SGP) in Oklahoma and Northern Slope Alaska site (NSA) in Barrow. The Ka-SACR and KAZR will be co-located at each of these sites. Calibration of the zenith pointing radar with very narrow beam widths has always been a very difficult task. In addition to the narrow vertical beam the use of frequency diversity pulse compression waveform with the newly deployed KAZR makes it even more challenging to calibrate the radar. The addition of a co-located Ka-SACR with short pulse and pulse compression capability provides an invaluable tool to cross-calibrate the KAZR with Ka-SACR. Both, SACR and KAZR can be calibrated with the traditional radar equation for volume target. However, the use of corner reflector calibration with SACR provides an additional constraint to verify the calibration state of KAZR. This paper presents the salient features of KAZR and SACR. The paper will also present the analysis of cross-calibration of the zenith pointing cloud radar using frequency diversity pulse compression with scanning cloud radar.