Exploring Commercial GNSS RO Products for Planetary Boundary Layer Studies in the Arctic Region

Commercial GNSS RO products are being touted for their coverage in polar regions where COSMIC-2 observations don’t reach. This study seeks to explore their value for Arctic PBL investigations where sufficient lower atmospheric penetration of GNSS RO is vital for representing the persistently shallow PBL. Both NASA purchased commercial RO products, Spire and GeoOptics, have improved lower tropospheric penetration probability over the Arctic Ocean compared to MetOp observations, with Spire having greater volume of observations (nearly two orders of magnitude) compared to GeoOptics. A seasonal cycle is evident in the RO penetration probability (except for Spire) that is found to be related to the water vapor pressure. For winter months, at the 500m level, which is the standard cut-off threshold used for GNSS RO PBL studies, both products yield a penetration probability of ~80% of total observations over the Arctic Ocean and up to ~100% over the frozen sea ice region. As a result, both products are able to sufficiently represent the shallow Arctic PBLH (less than 300m depth) which is comparable to the PBLH from MERRA-2 reanalysis, unlike MetOp observations which fails to capture PBL heights below 400m.