What Parameters are the Most Important to Smoke Plume Rise?

A number of schemes, including Daysmoke and the Briggs formulas, have been developed for or applied to estimating smoke plume rise of prescribed burning. The Briggs formulas were originally developed for power plant stacks, while Daysmoke is a dynamical model to simulate movement and deposition of smoke particles emitted from fires. Recent case studies indicate a substantially large difference between the two schemes. This can be one of the major sources for uncertainties in modeling the air quality effects of wildland fires. This study seeks to understand the difference between the two methods using the Fourier amplitude sensitivity test (FAST) to identify the most important parameters in each scheme. FAST determines the relative contribution of individual model input parameters to the variance of the model output. For the FAST analysis of Daysmoke, a set of 13 parameters is examined. A range of values for each of the parameters is specified based on measurements of prescribed burning or empirical estimates, and a statistical distribution is assumed. Daysmoke is run for tens of thousands of different combinations of the parameters. FAST analysis is also done for Briggs formulas. The preliminary results indicate that size of the burning, temperature perturbation, and plume entrainment are the most important parameters for the estimation of plume rise. Thus it is critically important to know the proper forms and to specify the correct values of these parameters in the schemes of smoke plume rise.