Numerical Exploration of the Stable Atmospheric Boundary Layer

Simulating the stable atmospheric boundary layer (SABL) presents a significant challenge to numerical models due to the interactions of several processes with widely-varying scales. The goal of this Challenge Project is to more clearly define the role of gravity wave-turbulence interactions as a mechanism for localized destabilization in the SABL. The numerical scheme employed is a fully-prognostic second-order closure (SOC) scheme implemented in the National Taiwan University/Purdue University Non-hydrostatic Model (NTU/P). Use of second-order closure is more complex and resource intensive than eddy-viscosity (EV) schemes; however, we find the SOC scheme adds significant detail. Growth-rates for the primary and secondary instabilities were greater, even when compared to EV model runs with doubled resolution. The enhanced detail includes the excitation and absorption of gravity waves. As part of the verification efforts, we are employing observational data from the Meteor Crater Experiment in 2006 to study boundary layer evolution, as well as transient features generated by wind-flow over the crater. While some features are qualitatively similar, a more comprehensive evaluation of the SOC scheme is forthcoming, as additional observations are included.