TIGAR barotropic instability experiments for studying the instability of the QBO circulation

The barotropic version of the TIGAR (Transient Inertia-Gravity And Rossby wave dynamics) model has been run to simulate the effect of barotropic instability development on QBO-like equatorial zonal jets. The instability was triggered by adding a large-amplitude initial height perturbation to the experiments. The background flows include analytical jets that show revearsal of the barotropic vorticity gradient, thereby satisfying the necessary condition for barotropic instability. TIGAR solves the rotating shallow water equations on the sphere by applying Hough harmonics as spectral basis functions, thereby enabling the direct analysis of Rossby and inertia-gravity waves, as well as the mixed Rossby-gravity wave from the model output. More details of the model are available at:  https://doi.org/10.1002/qj.4006 . The file "BI_TIGAR_sp.tar.gz" contains the simulations in spectral space (T85 triangular truncation), whereas file "BI_TIGAR_phys.tar.gz" contains the simulations in gridpoint space on an F64 Gaussian grid.