Profiling Airborne Microwave Radiometer for Atmospheric and Cloud Research

Improved measurements of the atmospheric thermodynamic state, including water vapor and clouds are necessary to improve our understanding of many atmospheric problems. Clouds and water vapor are major players in environment and their accurate measurements are very important for furthering the scientific understanding of weather and climate. Unmanned aerial systems - UAS- are a new platform that can make such observations more frequently, more accurately and more affordable, but a lightweight, low power, autonomous sensors are lagging in development. Microwave radiometers are uniquely capable of measuring path-integrated liquid water and water vapor in clouds and providing ice/water phase partitioning by mass within a given volume. The need for such an instrument was identified as the number one priority by The Department of Energy Biological and Environmental Research Office’s Aerial Observational Needs Workshop in 2015. Existing microwave radiometers are notoriously large and demanding of electrical power, and thus present a challenge to airborne observations. A lightweight (4.6 kg), low power consuming (less than 75 W), small (830 mm long and 100 mm diameter) airborne microwave radiometer for atmospheric observations is being developed under this project. Profiling Airborne Microwave Radiometer - PAMR - will provide measurements in two polarizations within three bands: 60-90, 150 and 183 GHz. It is a modular instrument for which other radiometer bands or additional sensors for the PAMR can be developed in the future. PAMR is a “plug and play” instrument, operating autonomously from an- aircraft requiring only power from the hosting platform. A novel type of the microwave radiometer receiver is the heart of our technological improvement. It enables a radiometer operation on a small UAS without a thermal or pressure control while improving radiometer calibration and sensitivity. It also promises a more reliable operation in the rugged environment of UAS operations. A design of the PAMR was completed during the Phase II of the project. Major components for receivers were modelled, built, evaluated, and implemented into the radiometers’ layout. Other parts of the PAMR, such as motion and data acquisition systems were built. The objective of the Phase IIA project is to develop a fully functional prototype ready to take data in a field deployment. The radiometric receivers developed under this project have the potential to become a disruptive technology and improve weather observations around the planet. Small satellites welcome compact, low power sensors and they will be the next generation Earth observing platforms from space. Improved ground-based observations of the atmospheric boundary layer can significantly improve local and severe weather forecasting. Deployment on an ocean buoy, for example for offshore wind power generation, can make the cost of this energy more competitive on the market.