Evaluation of Spire GNSS RO data for global tropopause and PBL detections

Abstract:

Level 1 Global Navigation Satellite System (GNSS) radio occultation (RO) data provided by Spire are processed by UCAR/COSMIC into level 2 neutral atmospheric products. There are averagely ~560 atmospheric profiles/day provided after quality control. Scientific evaluation of these Spire atmospheric data addressed the ability to observe the tropical cold-point tropopause (CPT) height and temperature and the planetary boundary layer (PBL) depth. It is found that Spire RO data are suitable for studying the structures and temporal and spatial variabilities of the tropopause. Despite having low SNR, the Spire RO have good penetration depth. By defining the PBL depth as the altitude at which the vertical gradient of the refractivity is minimum, we calculated the PBL depth from RO profile and investigated the ability of Spire RO data in detecting the PBL height. The results show that Spire data can be a good data source to study the global PBL structure and variability. However, since the spatial coverage of the Spire data is limited (because its existing constellation is driven by the communication service requirements), it may be necessary to correct uneven sampling problems when applying the Spire data for climate study.