Experiment will examine gravity waves in the middle atmosphere

Abstract

Over the last 4 decades, the study of high‐frequency gravity waves with periods from minutes to several hours in the stratosphere, mesosphere, and lower thermosphere has been a leading area of research in both meteorology and aeronomy. This interest has been natural, since gravity wave motions often dominate the variance observed in the upper mesospheric and thermospheric wind field, and since the vertical transport of mean flow momentum by gravity waves is now thought to play a key role in maintaining global‐scale circulation throughout the middle atmosphere.Part of the spectrum of the gravity waves propagating upward through the mesosphere will reach F‐layer heights, where the gravity waves account for temporal and spatial variability in electron density Electron density, in turn, can affect aspects of radio wave propagation. Gravity waves in the equatorial F‐region may also trigger large‐scale ionospheric instabilities, which account for the “spread‐F” phenomenon. Late next year, investigators involved in the Darwin Area Wave Experiment (DAWEX) will make detailed coordinated observations of the gravity wave field in the mesosphere and thermosphere with unprecedented areal coverage, and will attempt to relate these observations to a particularly well‐defined and intense tropospheric source.