GNSS radio occultation soundings from commercial off-the-shelf receivers on board balloon platforms

Abstract

The Global Navigation Satellite System (GNSS) radio occultation (RO) technique has proven to be an effective tool for Earth atmosphere profiling. Traditional spaceborne RO satellite constellations are expensive with relatively low sampling density for specific regions of interest. In contrast, in-atmosphere RO platforms can provide much higher spatial and temporal sampling of ROs around regional weather events. This study explores the capability of a low-cost and scalable commercial off-the-shelf (COTS) GNSS receiver on board high-altitude balloons. The refractivity retrievals from balloon-borne RO payloads obtained from two flight campaigns (World View and ZPM-1) are presented. The balloon-borne RO soundings from the World View campaign show refractivity profiles between 6 and 19 km, with overall near-zero median difference from colocated ECMWF ERA5 reanalysis data and variability comparable to spaceborne RO missions (∼ 2.3 % median absolute deviation or MAD). Soundings from the ZPM-1 campaign show a relatively large positive refractivity bias (∼ 2.5 %). In summary, low-cost COTS RO payloads on board balloon platforms are worth further engineering and study in order to provide capabilities for dense, targeted atmospheric soundings that can improve regional weather forecasts via data assimilation.