Brzezinski, A.: 1994, Polar motion excitation by variations of the effective angular momentum function: II.
The authors express their thanks to Michael Schindelegger (TU Vienna), who kindly provided the atmospheric angular momentum functions based on MERRA data.
and Schuh H.: 2011, High-resolution atmospheric angular momentum functions related to Earth rotation parameters during CONT08.
The effects of geophysical excitations in nutation are caused by quasi-diurnal changes of angular momentum functions of the atmosphere and oceans, expressed in terrestrial frame.
However, this effect was found to be different for different sources of atmospheric/oceanic angular momentum functions (Ron et al., 2011).
** Pressure (matter) and wind (motion) terms of atmospheric angular momentum functions (AAMF) from NCEP/NCAR re-analysis (Salstein, 2005).
The series of effective angular momentum functions
[chi] in terrestrial frame (in complex form) were subject to the complex demodulation (Brzezinski et al., 2002) at the retrograde diurnal frequency by removing a constant part which would lead to a big diurnal signal and by using a simple formula [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], where [phi] is the Greenwich sidereal time.
* Atmospheric and oceanic angular momentum functions
are now available from different sources.
To this end, we use the atmospheric and oceanic angular momentum functions that are now available from different agencies.
* Atmospheric angular momentum functions (pressure + wind terms):
* Oceanic angular momentum functions (matter + motion terms):
There are atmospheric angular momentum functions
(AAM) available from the IERS Special Bureau for the Atmosphere with sub-diurnal resolution (in 6-hour intervals) from the NCEP/NCAR re-analysis of atmospheric data (Salstein, 2005); oceanic data are publicly available only in daily intervals.