Atmospheric Contributions to Earth Nutation: Geodetic Constraints and Limitations of the Torque Approach

Abstract

Atmospheric motions in the retrograde diurnal (S1) band are of interest to a wide community of researchers in earth dynamics and geodesy, due to their potential contribution to the low-frequency motions of the rotation axis known as nutations. Previous studies of these effects have noted an order-of-magnitude discrepancy between estimates of atmosphere-induced nutation based on the torque and angular momentum approaches. In this note, angular momentum budgets computed from NCEP reanalysis data are examined in order to isolate the reasons for this discrepancy, and associated constraints on the atmospheric response to solar diurnal forcing are considered.