Angular momentum budgets based on NCEP and ECMWF reanlaysis data: An intercomparison

Joseph Egger, Klaus Peter Hoinka, Klaus Weickmann, Huei Ping Huang

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


An intercomparison of the reanalysis datasets of NCEP and ECMWF is performed with respect to the response of the axial angular momentum M to the torques. While both sets satisfy the budget equations of M reasonably well (except for the time mean). this is not the case with respect to the budget equations for the difference of both sets, where the analysis data explain only a small fraction of the difference of the angular momenta in terms of the difference of the torques. It is hypothesized that the larger fraction of the difference is a manifestation of analysis error. The autocorrelation functions of the differences of the mountain and friction torques between both sets exhibita a long memory, which reflects errors in the low-frequency components of the datasets. Probability distributions of M are considered as well. It is shown that the mean torque for a given M has to be positive (negative) for negative (positive) deviations of M. It is found that the NCEP torques, as analyzed, satisfy this basic requirement. The distribution of the difference of the angular momenta cannot be explained on the basis of the corresponding difference of the torques.

Original languageEnglish (US)
Pages (from-to)2577-2585
Number of pages9
JournalMonthly Weather Review
Issue number11
StatePublished - Nov 2003
Externally publishedYes

ASJC Scopus subject areas

  • Atmospheric Science


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