ARM Radar Calibrations and Cloud Variation during the EPCAPE Field Campaign

The U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) user facility recently deployed its mobile facility at La Jolla, California for the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE) campaign (15 February 2023 - 14 February 2024). The campaign focuses on characterizing the extent, radiative properties, aerosol interactions, and precipitation characteristics of stratocumulus clouds in the Eastern Pacific at a coastal city. As part of its mobile facilities, ARM deployed one of its scanning Ka/W-band cloud radars (SACR) at the Scripps Mt. Soledad site in La Jolla, and its Ka-band ARM Zenith Radar (KAZR) at the nearby (approx. 2 km) Scripps Pier.

This work focuses on ARM radar data monitoring and relative calibrations during the initial stages of this campaign using comparisons with collocated disdrometers, and with collocated partner radars, i.e., the Jet Propulsion Laboratory (JPL) CloudCube radar, which is a compact, multi-frequency vertical profiling radar for suborbital platform. A newly implemented relative calibration technique capitalizing on times of wet-radome attenuation in rain has also been included for assessing the quality of KAZR measurements. These comparison processes will represent the basis for what will be considered “calibrated b1 level radar datasets” available on ARM Data Discovery with corrected reflectivity. This dataset will also serve as the basis for ARM value added products, such as the Active Remote Sensing of CLouds (ARSCL) product and baseline microphysical retrieval (MICROBASE) products. A supplemental activity extending from this work examines the seasonal variations of clouds from the ARSCL and MICROBASE products and their association with the thermodynamic and dynamic environments.