Measuring and Assessing GNSS Radio Occultation (GNSS-RO) Profiles from Balloon Platforms

Since 1995, space-based GNSS-RO has made significant impacts on weather forecasting, climate prediction, and space weather research. However, it is difficult to remote sense the planetary boundary layer from space-based ROs due to geophysical and technological limitations (e.g., low signal-to-noise ratio, atmospheric ducting, and antenna gain loss). In addition, space-based RO systems lack the agility to provide persistent, on-demand RO data for specific regions of interest, such as for areas with impending acute weather events. The high cost and lengthy time associated with launching LEO constellations can make these systems unsuitable for adapting to the ever-changing network of GNSS constellations and incorporating the newest advances in GNSS receiver technology.

In this paper, we discuss preliminary results from a balloon-based platform with COTS (commercial off-the-shelf) receivers that measure GNSS-RO soundings. We derive the instrument specifications from COSMIC science measurement requirements, and explain the design of our receiver and antenna along with the platform developed for hosting the payload on high altitude balloons. We show preliminary results from our ground-based validation campaign, a controlled hot-air balloon launch, and a high-altitude helium balloon launch. A data quality assessment of this data is made, which is compared to typical COSMIC data. Our results help us understand the feasibility of carrying out such measurements from an operations and scientific perspective. The feasibility of providing balloon-based RO data, and the upper limitations of such data quality is described. We also discuss the lessons learned in terms of changes that should be made to our system to fully deploy a network of balloon-borne receivers. With these system changes, we illustrate how our GNSS-RO data may be assimilated into NWP models in the near future.