Detecting Signatures of Giant Hail Events With Integrated GNSS Tomography: A Case Study Over Southern Poland

Monitoring heavy rainfall and hailstorms is essential for understanding atmospheric processes. Due to the insufficient temporal and spatial resolution of commonly used instruments (e.g. radiosondes), new methods of atmospheric remote sensing are suggested. One such method evaluated in this work involves the latest advancements in Global Navigation Satellite System (GNSS) water vapor monitoring; the integration of ground-based GNSS observations and radio occultation (RO) retrievals in the inverse Radon transform processing. Three hailstorms, with hailstones larger than 10 cm, over Poland are studied to gather information about the lowermost troposphere and identify their signatures in wet refractivity values. The results are validated against radiosonde observations to assess the quality of the processing. A significant drop in wet refractivity values is observed in the periods preceding the convective events. With a processing error of less than 3.5 ppm, the drop averages 10 ppm.