The Benefits of Diverse Observation Platforms to Understand Multiscale Planetary Boundary Layer Processes

Processes within the planetary boundary layer (PBL) govern surface exchanges of moisture, heat, and momentum, influencing air pollution and severe weather. In urban environments, buildings and land cover changes create spatial contrasts that require high-resolution observations to advance understanding PBL processes. Advancements in ground-based and Uncrewed Aerial Systems (UAS) profiling instrumentation have led to increases in PBL observations capable of observing phenomena on short timescales. The TRacking Aerosol interactions with Convection ExpeRiment (TRACER) Coastal Urban Boundary layer Interactions with Convection (CUBIC) and UAS campaigns in Houston, Texas during the summer of 2022 gathered high spatiotemporal resolution data utilizing PBL profiling instrumentation. The projects provided a unique opportunity to investigate the benefits of using a network of PBL profiling systems and diverse collocated observation platforms. We demonstrate the advantages of collocated remote sensing and in situ profiling observations via a case study and instrument comparison. The spatial heterogeneity, structure, and evolution of a regional low-level jet are analyzed across four locations. We then combine and compare information from continuously operating ground-based remote sensors and collocated, high vertical resolution UAS data to capitalize on the strengths of both observation methods at one location. Results show fine-scale features and details of the PBL evolution, such as temperature inversions during the morning transition and observed Kelvin-Helmholtz waves following a sea breeze passage. The examples show that synergistic collocation of in situ UAS to reinforce ground-based remote sensing instruments can provide greater insights into meso-to-microscale processes in the PBL than any one sensor can provide.