A Regime-Based Assessment of GNSS Radio Occultation Retrievals in the Planetary Boundary Layer using ARM Radiosondes and Ceilometer Data

The past few decades of Global Navigation Satellite Systems (GNSS) Radio Occultation (RO) missions have provided significant amounts of useful thermodynamic data, with particular improvements in the last few years due to improved receiver design. The benefit of using GNSS RO over traditional passive microwave and infrared profilers is that GNSS RO can observe vertical thermodynamic profiles in all-weather conditions at high vertical resolution and deep into the atmosphere. The planetary boundary layer (PBL) and its height (PBLH) varies significantly with meteorological regime (e.g., polar or tropical, marine or terrestrial), which in turn can create issues for generalized PBL retrievals for remote sensing instruments. Highly variable thermodynamic biases between remote sensing observations and in-situ observations can be found across meteorological regimes, particularly in the PBL, which can limit the feasibility of combining different observations to obtained a merged PBL product. This study is the first to use both radiosonde and ceilometer data in various meteorological regimes to assess PBL thermodynamic biases in RO observations and of PBLH estimates using different methods and analysis variables for the purpose of creating a multi-sensor, global, minimally-biased merged PBL product for research use.