Tests on the validity of atmospheric torques on Earth computed from atmospheric model outputs

Abstract

The effect of the atmosphere on the Earth rotation is usually computed using the angular momentum budget equation. In particular, the interaction torque between the solid Earth/ocean and the atmosphere can be computed from the output of global circulation models. This torque is composed of three parts: a mountain torque due to the pressure action on the topography, a gravitational torque due to the interaction between the mass inside the solid Earth and inside the atmosphere, and a friction torque. The purpose of the paper is to test the torque computed from the output of different atmospheric global circulation models (GEOS‐1, National Centers for Environmental Protection reanalysis, and ERA‐15) in order to see to what extent they are reliable in the frame of Earth rotation studies. The test has been performed by comparing each part of the torque computed from the different models, as well as by verifying of the angular momentum budget equation for the atmosphere.