DEVELOPMENT OF A STRATOSPHERIC BALLOON HYPERSPECTRAL MICROWAVE RADIOMETER FOR PLANETARY BOUNDARY LAYER OBSERVATION

We present the development of a hyperspectral microwave radiometer for high-altitude balloon deployment to better observe the Planetary Boundary Layer (PBL) with an unprecedented sensitivity. The new hyperspectral radiometer is based on the existing High-frequency Airborne Microwave and Millimeter-wave Radiometer (HAMMR) instrument. Our key innovation from existing microwave sounders is increasing the number of channels around the oxygen and water-vapor absorption lines with high-resolution spectral sampling, thereby reducing profile retrieval errors and providing wide-band coverage over the frequency range of 18-200 GHz. In this paper, we present the overall system design, including the Stratollite subsystem, the full optical subsystem, RF front-end, and a software defined back-end. We will also show preliminary outdoor radiometric test results using a complete 48-72 GHz radiometer system. The hyperspectral HAMMR-HD balloon experiment will acquire up to 30 days of high-resolution PBL data, over a variety of weather conditions, and over land and ocean.