PBL Thermodynamic Profile Assimilation and Impacts on Land-Atmosphere Coupling

The planetary boundary layer (PBL) is a critical link in the coupling of the land and atmosphere and strongly influences weather prediction and convective initiation. Unfortunately, routine observations of PBL thermodynamic properties remain limited in space, time, and instrument capability (particularly from space). In this study, we examine the potential impacts of assimilating high quality PBL temperature and humidity profiles on land-atmosphere (L-A) interactions and short-term weather prediction using the NASA Unified WRF (NU-WRF) system. PBL profiles are obtained from ground-based remote sensing radiometer (AERI) and lidar (DIAL) instruments located over the Southern Great Plains of the U.S, and assimilation capabilities (EDAS) have been implemented into NU-WRF to assimilate these products. The case study to be examined is 11 July 2015 at the Ellis, KS site during the PECAN field campaign. Impacts of temperature and humidity profile assimilation and the assimilation window itself are examined In terms of impacts on the simulated PBL profile evolution, PBL height, and ambient weather (2-meter temperature, humidity, winds). In addition, impacts on temporal and spatial evolution of L-A feedbacks between soil moisture, surface fluxes and PBL are examined in the context of local coupling (LoCo) diagnostics combined with PBL and surface observations. Overall, this targeted study provides a foundation for the assessment of future ground-based profiling networks as well as spaceborne profilers that may be developed over the next decade, and their potential impacts on NWP and the scientific understanding of L-A interactions.