Over the last several years the Jet Propulsion Laboratory’s VIPR (Vapor Inside-cloud Profiling Radar) instrument has been validated in both ground and airborne deployments as a new approach to measure water vapor profiles inside clouds, as well as partial vapor columns in clear air between the sensor and Earth’s surface. As a 170 GHz differential absorption radar that provides its own scene illumination, VIPR’s advantages over better-established passive techniques include the potential for higher vertical spatial resolution and the ability to perform humidity retrievals over land. Meanwhile, passive spectroscopy provides sounding information in clear air, with excellent horizontal resolution, and its use of widely spaced channels spanning both water and oxygen lines permits humidity and pressure profiles to be retrieved in a single measurement.
Under new Decadal Survey Incubator support, our team is preparing a joint airborne campaign, combining the VIPR with JPL’s HAMSR (High Altitude MMIC Sounding Receiver), to evaluate active and passive spectroscopy as a synergistic strategy to observe thermodynamics in the planetary boundary layer. We are tentatively targeting the ER-2 aircraft as an observational platform, which has previously carried HAMSR. To enable the integration of VIPR in a compact wing pod, the radar electronics, optics, and signal processor will be upgraded to enable autonomous operation with reduced along-track averaging distances. These improvements will better position VIPR to be a platform-agnostic airborne instrument for future PBL observations, and it will demonstrate key architectures that would be needed in future potential orbital missions using VIPR or similar high frequency radar instruments.