Analysis of Planetary Scale Waves Using Idealized Sudden Stratospheric Warming Simulations in Different Dynamical Cores

Planetary waves from the troposphere are known to play an important role in sudden stratospheric warming (SSW). To evaluate the representation of large-scale waves in idealized SSW simulations, three dynamical cores of the National Center for Atmospheric Research Community Atmosphere Model were tested in this study: the Eulerian (EUL) spectral-transform, finite-volume (FV), and spectral element (SE) models. Notable differences were observed among the dynamical cores, with FV being unable to generate major SSWs and simulating minor SSWs less effectively than the other models. Wave decomposition analysis revealed distinct planetary wave propagation patterns during the development of each event. Zonal Wave Number 2 wave activities primarily determined SSW types, and ZWN1 led SSWs to recovery during the ensuing periods. However, FV failed to adequately propagate large-scale waves in minor SSW events, preventing the reversal of stratospheric zonal-mean zonal winds. Interestingly, FV showed decreased upward Eliassen-Palm flux compared to that of other dynamical cores, even during climatology. Additional tests were performed to examine the reasons for FV's atypical results, but the dynamic impacts on planetary waves remain poorly understood. Planetary waves originating in the lower atmosphere play a significant role in sudden changes in the upper atmosphere's temperature, a phenomenon known as sudden stratospheric warming (SSW). In this study, we tested three different methods (Eulerian, finite-volume, and spectral element) in a computer model to evaluate their ability to simulate the large-scale waves of SSW events, and our results showed clear differences between the methods. The finite-volume method exhibited limited capability in producing major SSW events and proved to be less effective at simulating minor events compared to the other methods. Using wave analysis, we studied the processes of major and minor SSW events and found that different types of waves primarily determined the type of SSW event. In minor events, the finite-volume method could not simulate the correct movement of large-scale waves to alter wind patterns in the upper atmosphere. We also noticed that the finite-volume method exhibited a lower energy level compared to other methods, even in typical situations. Although we conducted additional tests to identify the reasons for these unusual results, the dynamic effects from the finite-volume method on planetary waves are still not entirely understood. Idealized sudden stratospheric warming (SSW) simulations from three atmospheric general circulation model dynamical cores were tested Role of large-scale waves' activity differed depending on different types of SSWs in Eulerian spectral-transform and spectral element cores Poor large-scale troposphere-stratosphere wave propagation limits finite volume core's simulation of major/minor SSWs