The Effective Atmospheric Angular Momentum (EAAM) is a combined project from the Met Office and the European Centre for Medium Range Weather Forecasting (ECMWF). The data is of 3 angular momentum components of the mass and wind terms at 12 or 24 hourly intervals. The ECMWF data is from 1979-93 and the Met Office data is from 1983-1997. This dataset is public.

There are four historical AAM datasets:

* AAM (NMC) - National Meteorological Center
* AAM (JMA) - Japanese Meteorological Agency
* AAM (UKMO) - Met Office
* AAM (ECMWF) - European Centre for Medium-Range Weather Forecasting