WRF Model Boundary Layer Height Validation Using the Vaisala Ceilometer

The parameterization of the planetary boundary layer (PBL) continues to be an important and active area of research in the modeling community. Major advances have been made in the representation of the sub-grid scale PBL processes over the past few decades as a result of comprehensive research studies. These advances have resulted in updates to existing PBL schemes and the addition of new PBL schemes into modern numerical weather prediction systems such as the Weather Research and Forecasting (WRF) model. In the interest of assessing the basic performance of some of the modern schemes available within the WRF version 3.4, this study performs an Intercomparison of boundary layer height as specified by various PBL parameterizations at locations where boundary layer height is routinely measured using Vaisala ceilometers. Boundary layer height was selected as the assessment variable for this study as it continues to be an important meteorological parameter across several atmospheric science disciplines including air quality, aviation, and most recently wind energy.

In classic intercomparisons of specific physical parameterizations embedded within numerical weather prediction systems, all modeling system components are held constant with the exception of the configuration option that allows the PBL scheme to change. Following this methodology, all configuration options are held constant within the WRF modeling system with the exception of the PBL scheme and its subsequent surface layer parameterization. Boundary layer height is then extracted from each model simulation and compared against verifying observations obtained using the Vaisala Boundary Layer View (BL-VIEW) application. BL-VIEW is an application software for planetary boundary layer analysis and is an independent data collection, storage, analysis, and presentation program designed to be used with the Vaisala Ceilometers CL31 and CL51.

This study not only provides an assessment of modern PBL parameterizations but also demonstrates the use of an operational boundary layer height observation instrument. While typical boundary layer studies utilize measurements from field, numerical, or idealized tank or wind tunnel experiments, the BL-VIEW dataset has a higher temporal resolution and when multiple ceilometers are deployed, a higher spatial resolution.