EXPERIMENTS WITH A LUNAR ATMOSPHERIC TIDAL MODEL

A lunar tidal model similar to that of Fort,es [1982] is used to inves tigate the effects of changes in background zonal winds on the structu re of the lunar tide in the upper atmosphere. It is found that changes in the winds have a greater effect than changes in the background tem perature profile with latitude, Observed changes in the structure of t he lunar tide from year to year at Saskatoon may be explained by intro ducing stratospheric warmings into the model. The addition of an assoc iated mesospheric cooling gives an even better fit to the observed pha se data. It is also seen that northern hemisphere warmings are predict ed to give considerable amplitude changes in southern hemisphere lunar tides. It is expected that much of the difficulty in measuring lunar tides in the upper atmosphere is due to changes in the tidal parameter s at these levels brought about by variations in the underlying atmosp here.