Comparison of satellite gravity wave measurements with a global ray tracing experiment

Standard techniques for extracting gravity wave (GW) temperature variances from infrared limb sounding satellite data were applied to a four-year series of temperature acquired by the SABER instrument. Prominent structures in the global distribution of monthly mean wave activity appear similarly in all years. Apart from strongly localized forcing by orographic and convective sources, many of these overall structures can be reproduced by a global ray-tracing experiment based on a homogeneous and isotropic launch distribution employing the GROGRAT ray tracer. Such measurement-tuned global GW modeling could be used for testing quantitatively some of the crude assumptions made in GW parameterization schemes in global models, such as (for instance) assuming wave propagation in a purely vertical column. Ambiguities in the measurement interpretation will, however, remain unless future limb-imaging instruments measuring at fine horizontal and vertical resolution can directly measure the magnitude and sign of the wave momentum flux.