Observational investigations of gravity wave momentum flux with spectroscopic imaging

Abstract

We apply a newly developed gravity wave momentum flux estimation method to the mesospheric measurements obtained with colocated airglow imager and meteor radar at Maui, Hawaii (20.7°N, 156.3°W), during the Maul Mesosphere and Lower Thermosphere (Maui MALT) campaign. The method identifies individual quasi-monochromatic gravity waves with periods between 6 and ∼40 min, estimates the intrinsic wave parameters, and calculates the momentum fluxes carried by vertically propagating waves. Data taken on 28 October 2003 are analyzed in detail to reveal the relationship between momentum flux and wave parameters. The January, April, July, and October 2003 data are divided into summer and winter categories, and nightly average momentum fluxes are calculated for comparison of the seasonal wave propagation directions. Average wave momentum flux is directed to the northeast during most of the summer nights, while a southwest preference exists for the winter nights. The results extracted from Maul, Hawaii, combined with the earlier results from Starfire Optical Range, New Mexico (35°N, 107°W), and other observations, support the notion that the seasonal trend in meridional flux is a global phenomenon. Copyright 2005 by the American Geophysical Union.