Title: P-band Signals of Opportunity Synthetic Aperture Radar Snow Mission Concept with A Multi-Element Antenna Array for the NASA Earth System Explorer Program
Presenting Author: Simon Yueh
Organization: Jet Propulsion Laboratory, California Institute of Technology
Co-Author(s): Steve Margulis2, Rashmi Shah, Steve Franklin, Xiaolan Xu, Justin Nguyen, Javier Bosch-Lluis, Richard Hodges, and Jacqueline Chen

Abstract:
Mountain watersheds play an outsized role in global hydrology and function as "water towers" to supply downstream needs that serve a large portion of the global population and its economy. Despite its importance, global mountain Snow Water Equivalent (SWE) remains essentially unobserved by satellites. As a result, SWE estimates in mountain areas remain highly uncertain, with the uncertainty projected onto current and future estimates of snow-derived water availability. This led to the recommendation in the 2017 Earth Science Decadal Survey that snow is the area of hydrologic remote sensing "most in need of new thinking" and was identified as one of seven Earth System Explorer (ESE) candidates for future competition. To this end, a satellite P-band Signals of Opportunity (SoOp) Synthetic Aperture Radar (SAR) mission concept has been developed, including a constellation of a few small satellites with receivers to detect reflection from signals emitted by the P-band (360-380 MHz) Mobile Users Objective System (MUOS) communication satellites. The SoOp SAR (SoOpSAR) instrument, combining the SoOp and SAR technologies can achieve a high-resolution imaging at a spatial resolution of ~100 m or better and a swath width of 240 kilometers. The SoOpSAR technique takes advantage of focused energy near the focal point and its ambiguity reduction after range, Doppler and interferometry processing. Here we will describe the published SoOpSAR design concept, which employs one receiver/antenna on each satellite and an enhanced SoOpSAR concept with a small array of 2 to 3 antennas to reduce the ambiguity to signal ratio (ASR) and therefore to increase the portion of the swath with ASR < 0.1 to above 70 percent. It is concluded that the use of a small antenna array can significantly improve the useful portion of the swath for the P-band SoOpSAR concept for remote sensing of snow and root zone soil moisture. We will also describe the results from an airborne campaign for the testing of SoOpSAR technology.