Sensitivity of WRF Model to Planetary Boundary Layer Schemes in Different Climate Zones over India

Thursday, 18 December 2014
Preeti Gunwani and Manju Mohan, Indian Institute of Technology Delhi, Centre for Atmospheric Sciences, New Delhi, India
Planetary Boundary Layer (PBL) parameterization schemes are important components of meteorological models and play critical role in simulating boundary layer. These schemes are used to resolve the terms associated with the momentum, heat and humidity turbulent fluxes and are responsible for vertical sub grid scale fluxes within boundary layer as well as free atmosphere. In the present work, sensitivity of Weather Research Forecasting (WRF) Model version 3.1.1, has been carried out with five PBL schemes – YSU, MYJ, ACM2, QNSE AND MYNN. The model performance has been evaluated over different climatic zones (Tropical, Temperate and Arid) over India. Simulated meteorological parameters – 2m temperature, 10m wind speed and direction, 2m humidity have been compared with observations through standard statistical measures. Boundary layer height computation methods are not coherent amongst PBL schemes, so large differences in predicted height is seen. Overall, model shows acceptable behavior but no particular scheme produces best performance for all parameters, locations and season. The goal is to study the relative performance of these schemes, selecting the option which overall shows best results and minimize uncertainty for future air quality simulations.