Estimates of the vertical flux of meridional momentum due to waves of periods between 8 min and 1 hour were obtained over a height range of approximately 80 to 94 km while the 2-day wave was active during January 1987. Between 0600 and 1100 LT on the days of the northward phase of the 2-day wave, pulses of momentum-flux density, somewhat larger than the values present at other times, were found. The interpretation of momentum-flux density profiles is considered and the concepts developed are applied to the data presented. It is found that the data are generally not consistent with the expected scenario of breaking upgoing gravity waves. An alternative explanation involving downgoing waves is tendered. ¿ 1998 American Geophysical Union