Characterizing the Turbulent Structure of the Convective Boundary Layer Over the SGP Using ARM/ASR Observations and LES Model Output

Poster PDF

Description

The aim of this project is to gain a better understanding of the entrainment zone of the Convective Boundary Layer over the SGP site. Profiles of higher order moments of the water vapor mixing ratio are compared between 10-s Raman lidar observations and Large Eddy Simulations (LES) output. Overall, LES tends to underpredict the variance in the entrainment zone, and the profile of skewness derived from the LES output is markedly different than the Raman lidar observations also. However, our results markedly improved after driving the LES with the ARM variational analysis product, instead of with mesoscale numerical results retrieved from the WRF model. A parameter study on the determining factors that set the variance and skewness are presented, as well as simulations from several models (OU-LES, WRF, and DALES) to test the robustness of our results. The free tropospheric humidity is an important driver of the variability in the entrainment zone. The ergodicity of the system is evaluated by comparisons of the variance and skewness over time and over space. We also present improvements of the thermodynamic profiles retrieved by the AERIoe algorithm. We will present both results from the PECAN field campaign as well as instrument simulator results. In the latter, we generated AERI observations from LES model output, applied the AERIoe retrieval algorithm, and compared the resulting profiles with the true profiles generated by the LES. This allows us to investigate how small-scale inhomogeneities in the water vapor and temperature field affect the AERIoe retrieved profiles. Additionally, this serves as an initial step towards the implementation of an on-line simulator in LES.