The Global Planetary Boundary Layer Height Climatology over Oceans using COSMIC-2 and Spire GNSS RO Bending Angles

The planetary boundary layer (PBL) is an essential component of the troposphere, controlling rapid exchanges of heat, moisture, and chemical constituents between the surface and free atmosphere. In this study, we demonstrate how to use the bending angle (BA) vertical profiles from two recent Global Navigation Satellite System (GNSS) Radio Occultation (RO) missions, Formosa Satellite Mission 7– Constellation Observing System for Meteorology, Ionosphere, and Climate-2 (COSMIC-2) and Spire, to detect the planetary boundary layer height (PBLH) over global oceans. The estimated PBLH from RO data is compared to the height of the boundary-layer-cloud-top (BLCTH), which is derived from the lidar measurements taken by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument onboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite specifically focusing on regions with stratocumulus clouds over tropical-subtropical oceans. Comparisons are further made between the RO PBLH and the PBLH outputs from the two widely-used reanalysis products: European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis version 5 (ERA-5) and Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2), as well as one forecast model, National Center of Environmental Prediction (NCEP)-Climate Forecast System (CFS). The results show that the RO PBLH is highly consistent with the BLCTH from CALIOP. Also, despite differences in spatial sampling, COSMIC-2 and Spire consistently produce highly comparable PBLH results. We also quantified the temporal and spatial variation of PBLH from RO data and those from the reanalysis and forecast model.