Papers on Climate and Atmospheric Physics
The balance of global angular momentum in a long-term atmospheric data set
Article first published online: 21 SEP 2012
Copyright 1999 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 104, Issue D2, pages 2031–2040, 27 January 1999
How to Cite
1999), The balance of global angular momentum in a long-term atmospheric data set, J. Geophys. Res., 104(D2), 2031–2040, doi:10.1029/1998JD200068., , and (
- Issue published online: 21 SEP 2012
- Article first published online: 21 SEP 2012
- Manuscript Accepted: 26 OCT 1998
- Manuscript Received: 2 AUG 1998
The balance of global atmospheric angular momentum is examined in a long time series of “reanalysis” data generated at the National Centers for Environmental Prediction (NCEP). A systematic negative bias of about −10 Hadleys (1018 kg m2 s−2) is obtained in the total torque in all seasons. The sum of the frictional (TF) and mountain (TM) torques contributes about half of this negative bias in the northern summer and autumn. The torque due to the parameterized gravity wave drag, TG, contributes the other half of the negative bias in summer but contributes the whole of it in winter. In the annual mean the projected angular momentum imbalance due to TG exceeds that due to TM + TF. Consistent with the budget analysis of the assimilated data, losses of angular momentum are also found in an extensive set of medium-range forecasts made with the NCEP reanalysis model. The average rates of loss of relative angular momentum in these forecasts, −7 Hadleys in January and −6 in July, are comparable to the bias of the total torque in the angular momentum budget. Further investigations are suggested to determine the model error, especially that associated with the parameterized gravity wave drag, related to the budget imbalance found in this study.