DEEPWAVE: Spatial and Fourier Ray Modeling of Mountain Waves

Computational Physics Inc, Springfield VA

Investigators

Abstract

This project will be part of the international DEEPWAVE campaign which will seek to understand the generation and propagation of atmospheric gravity waves from orographic and other sources from ground-level up to 100 km altitude, and will use airborne and ground-based instrumentation as well as modeling. It will take place in June/July 2014 in the region over New Zealand, Tasmania and the surrounding Southern Ocean. This project will provide ray-tracing analysis and forecasts for DEEPWAVE, with an emphasis on mountain waves. Two complementary ray formulations will be used: Fourier space ray-tracing and spatial ray-tracing. The Fourier-space ray-tracing is mainly for the region directly above mountains, where wave amplitudes tend to be highest and where spatial ray-tracing often fails to satisfy slowly varying requirements. The Fourier-space ray-tracing can also be coupled to a mesoscale model simulation to improve initial conditions for the Fourier-space rays. The spatial ray-tracing is mainly for mountain-wave propagation through the Polar Night Jet, with a new treatment of the three-dimensional geometrical spreading by horizontally and vertically varying wind shear. The work will involve a new analysis of geometrical spreading, a process that is omitted from almost all ray-tracing studies of gravity waves and that is likely to be important in the DEEPWAVE region. Aspects such as the directionality and anisotropy of the geometrical spreading will be examined for the first time and may provide clues for improved gravity wave parameterizations. The DEEPWAVE project will promote international scientific collaboration. Understanding gravity wave propagation and breakdown in the middle and upper atmosphere is related to a number of strategic and societal issues, including the safety of high altitude aircraft, the accuracy of weather and climate models, and the ability to forecast certain space weather phenomena that affect satellite communication.