Comparing Statistical Flow Analysis between Two Finite-Volume Shallow-Water Model Solvers on Icosahedral Grids

Statistics for detailed flow-behavior at high resolutions, such as energy spectra, probability distribution function for velocity and enstrophy, as well as their high order moments, can serve as an important measure for model reliability in weather and climatology. It is also important for understanding the sources of complex multiscale interactions within the flow. Here we plan to perform simulations for the finite-volume icosahedral A-grid versus C-grid shallow water models at kilometer-scale resolutions with initial conditions selected to excite energy cascades under non-forcing conditions. Once memory of the initial flow is lost, statistics for the flow of a single atmospheric layer will be used to compare numerical behavior of the two grid-staggering models. One expects differences between a single-layer flow and three-dimensional flow in energy spectra. Differences in spectral range, indices and high order statistics are expected between the two grid-point models, which would help gauge the implicit dissipation associated with numerics and the explicit dissipation formulation (e.g. Skamarock et al. (2014)). This will provide an initial assessment of the ability of the methods to model scale interactions.

Reference: Skamarock, W.C., S. Park, J.B. Klemp, and C. Snyder, 2014: Atmospheric Kinetic Energy Spectra from Global High-Resolution Nonhydrostatic Simulations. J. Atmos. Sci.,71, 4369–4381, https://doi.org/10.1175/JAS-D-14-0114.1