A numerical study of high frequency velocity and temperature perturbations induced by a low-intensity prescribed fire

High-frequency wind and temperature perturbations induced by prescribed or widlland fires play an important role in local-scale smoke transport and dispersion and in fire behaviors. However, little is known about the ability of atmospheric numerical models in capturing high-frequency perturbations in the vicinity of fires. In this study, the velocity and temperature perturbations generated by a low-Intensity prescribed fire (LIPF) are simulated using the Advanced Regional Prediction System (ARPS). The ARPS simulations, which was performed on a 1024-CPU high performance computer (HPC), employed very-high spatial (< 10 m) and temporal (> 10-Hz or less 0.1 second in integration time) resolution to explicitly resolve small-scale perturbations. A convective plume was initiated by introducing a very hot surface patch with temperatures up to 1000 K. The simulated 10Hz model output were used to compute the velocity and temperature perturbation fields and turbulence kinetic energy (TKE) associated with the LIPE convective plume. The simulated velocity and temperature perturbation fields as well as TKE were compared to the observed high-frequency data from a recent LIPF field experiment conducted by USDA forest Service Northern research Station on a forested plot in the New Jersey Pine Barrens as part of a Joint Fire Science Program project to develop modeling tools for predicting smoke dispersion from low-intensity prescribed fires.