Calibration and Flight Test of NAW W-Band Radiometric Mode

The National Research Council of Canada (NRC) operates NRC Airborne W-band (NAW) cloud radar onboard the NRC Convair-580 research aircraft. In this study, we implemented and tested a passive channel to the W-band radar, enabling the reception of radiometric and radar measurements of clouds in an interleaving mode, unlike CloudSat Cloud Profiling Radar. This paper presents the calibration procedure of the new radiometric mode and its verification against a radiative transfer model under clear-sky conditions. In the analysis, we include the derivation of a robust temperature-dependent correction that mitigates environmental bias in the sky data. Calibrated brightness temperatures show great sensitivity to liquid clouds, as shown by staircase sampling of a warm stratocumulus cloud deck.