Addressing the Question of Large-Scale Nonlinear Wave Coupling in the Space-Atmosphere Interaction Region

Abstract:

Theory and past observations have provided evidence that atmospheric tides and other global scale waves may nonlinearly interact to produce additional secondary waves throughout the space-atmosphere interaction region. However, very few studies have investigated the generation region of nonlinearly secondary waves, and as a result, the manifestations and impacts of these waves are still poorly understood. This study focuses on the nonlinear interaction between the quasi two-day wave (QTDW) and the migrating diurnal tide (DW1), two of the largest global scale waves in the atmosphere. The fundamental goal of this effort is to characterize the forcing region of the secondary waves and understand how it relates to their manifestation on a global scale. First, techniques are applied to Aura-MLS and TIMED-SABER satellite observations to compute the secondary waves, and their momentum and thermal forcing. These quantities are used to force the Global Scale Wave Model (GSWM) in order to calculate secondary wave responses. Results using the GSWM show that the secondary waves are significant well into the lower thermosphere-ionosphere system, and thus are likely to produce significant dynamo electric fields. Additionally, numerical experiments with the GSWM are conducted to further elucidate the relationship between the forcing and response of the secondary waves arising from QTDW-DW1 interaction.