A Higher-Order Ray Approximation Applied to Orographic Gravity Waves: Gaussian Beam Approximation

• DOI: 10.1175/2010jas3468.1
• Publication Date: 2010-08-27T20:11:45Z
• Authors: Manuel Pulido; Claudio Rodas
• Keywords: Orography; Orographic lift; Wavenumber; Forcing (mathematics)

Abstract Ray techniques are a promising tool for developing orographic gravity wave drag schemes. However, the modeling of propagation waves using standard ray theory in realistic background wind conditions usually encounters several regions, called caustics, where first-order approximation breaks down. In this work authors develop higher-order than theory, named Gaussian beam approximation, that depends on height. The analytical results show formulation is free singularities arise theory. Orographic propagate turns with height—the same as Shutts—are examined under approximation. evolution amplitude well defined even at caustics and forcing level. When comparing from high-resolution numerical simulations compute exact solution, there good agreement phase fields. Realistic orography represented by means superposition multiple Gaussians wavenumber space fit spectrum orography. technique appears to give representation disturbances generated flow over