The atmospheric contribution to precesion-nutation.

International audienceThe atmosphere takes a minor but non-negligible part in precession-nutation. The intensification of meteorological observations as well as global reanalyses have enabled the computation of the diurnal fluctuation of the atmospheric torque or the atmospheric angular momentum with respect to the terrestrial frame. The associated contribution to the precession-nutation has been estimated by various authors. The most important effect, on the annual term, is up to 0.1 mas. However accurate modelling is not yet available, mostly because of our lack of knowledge of the atmospheric-oceanic interaction