Sensitivity of Gravity‐Wave Momentum Flux to Moisture in the Mei‐Yu Front Systems

Abstract

The sensitivity of gravity‐wave momentum flux in the Mei‐Yu front systems to moisture is investigated via idealized simulations with various degrees of initial moisture content. Gravity waves generated in moist experiments result in net northward momentum flux and drag forcing, and the drag is indistinctive in the lower stratosphere near the tropopause but strengthens with height. As moisture content increases, the meridional flux intensifies remarkably in both physical and spectral space and extends to smaller spatiotemporal scales. However, the change of moisture has little effect on the selectivity of the strongest flux to relatively large scales and specific phase speeds. At slow phase speeds, the fanlike waves excited by the front are effectively coupled with the convective waves excited by the prefrontal moist convection, which leads to the weakening of the coupled wave flux.

The Influencing Mechanism of a Mid‐Latitude Westerly Trough on Stratospheric Gravity Waves Generated by Typhoon Lekima (2019)

“…GWs can be generated by many sources, such as topography (Liu et al., 2018), convection (S. Kim et al., 2005; S. Y. Kim et al., 2007; Y. Wang et al., 2018; Wang, Zhang, Zhang, & Guan, 2019; Wang, Zhang, Zhang, Peng, & Yu, 2019; J. Wu et al., 2018), and the jet stream (Wei & Zhang, 2014; Zhang, 2004). Jet stream or trough is a common source of mesoscale GWs by balance adjustment (Zhang, 2004).…”