Moisture Transport Dynamics within the Convective Boundary Layer: Insights from the Southern Great Plains ARM Site

Increasing our understanding of moisture transport within the convective boundary layer (CBL) is crucial for improving weather and climate forecasting. Turbulent moisture fluxes within the CBL are critical for precipitation, cloud formation, the surface energy budget, and the initiation of deep convection. Despite the importance of moisture transport, most previous studies have focused on dry CBLs in the absence of humidity. Furthermore, the transport of moisture and other scalars such as temperature can be highly dissimilar, with their statistics largely determined by their respective entrainment zone structure. Thus, many aspects of moisture transport in the CBL remain poorly understood.

This study aims to address these knowledge gaps by examining high-resolution observational data from the Southern Great Plains (SGP) Atmospheric Radiation Measurement (ARM) site in Lamont, Oklahoma, collected during the summer of 2018. Using data from Doppler lidar, Raman lidar, and eddy covariance measurements, we investigate the extent to which turbulent humidity statistics adhere to mixed layer similarity. We analyzed the data as a function of global stability (−z_i/L), as well as evaporative fraction (E_f) and humidity entrainment flux ratio (φ_wq), which are not accounted for in classical mixed-layer similarity theory. Additionally, we examine the impact of large-scale motions on scalar transport in the CBL as a function of stability and humidity entrainment zone properties.