A Parameterization Scheme Accounting for Nonhydrostatic Effects on the Momentum Flux of Vertically Propagating Orographic Gravity Waves: Formulas and Preliminary Tests in the Model for Prediction Across Scales (MPAS)

• DOI: 10.1175/jas-d-23-0020.1
• Publication Date: 2024-02-26T11:40:50Z
• Authors: Xin Xu; Rongrong Zhang; Miguel A. C. Teix...; Annelize van Niekerk; Ming Xue; Yixiong Lu; Haile Xue; Runqiu Li; Yuan Wang
• Keywords: Orographic lift; Momentum (technical analysis); Orography

Abstract The momentum transport by orographic gravity waves (OGWs) plays an important role in driving the large-scale circulation throughout atmosphere and is subject to parameterization numerical models. Current schemes, which were originally developed for coarse-resolution models, commonly assume that unresolved OGWs are hydrostatic. With increase horizontal resolution of state-of-the-art smaller scale more influenced nonhydrostatic effects (NHE), thus challenging use hydrostatic assumption. Based on analytical formulas derived our recent study, wave drag (OGWD) scheme Model Prediction Across Scales revised accounting NHE. Global simulations with 30-km conducted investigate NHE their impacts boreal winter. evident regions complex terrain such as Tibetan Plateau, Rocky Mountains, southern Andes, eastern Antarctica. parameterized surface flux can be either reduced or enhanced depending relative importance model physics–dynamics interactions. corrections OGWD significantly reduce easterly biases polar stratosphere Northern Hemisphere, due both weakened upper troposphere lower suppressed upward propagation resolved into stratosphere. However, only has a weak influence Southern Hemisphere during