Numerical experiment to revisit micrometeorology and sound speed calculations in forests

Abstract

A recent paper (Tunick and Swearingen in Appl Acoustics 70:857–867, 2009) presented a finite-difference computer model to calculate the microphysical influences on sound wave propagation in forests. Several numerical tests were conducted to assess model code capabilities using micrometeorological and acoustic field data. Calculated wind, temperature, and specific humidity profile data compared favorably to measured data. Nevertheless, we recommended investigation of alternate numerical schemes to determine the best formulation for micrometeorological-acoustic research applications in forests. Hence, in this paper, we conduct a numerical experiment that focuses on the pressure gradient term in the conservation of momentum equation. In particular, we implement a numerical iteration of this term at each time step of the calculation. This modification yields a more nearly incompressible flow, thus producing an alternative representation of the physics for the simulation of interest. Differences in the computed wind, temperature, and sound speed fields for the runs with and without implementing the iteration scheme are illustrated graphically and discussed.