The relationship between inter-annual and intra-annual variability in atmospheric angular momentum in a GCM with climatological SSTs

The internally generated interannual variability in absolute angular momentum is examined with a 100-year run of a GFDL, GCM. The interannual variation in the model's globally integrated and annually averaged absolute angular momentum (GAAM) is found to be a moderately large fraction of the changes in the GAAM observed in the atmosphere. Three modes are found: a tropical mode that represents a strengthening and weakening of the tropical easterlies, and two extratropical dipole models, one in either hemisphere, that represent latitudinal shifts of the jet maxima. It is shown that the interannual variability of all three modes can be interpreted as resulting from climate noise. The absolute angular momentum budget of all three modes is examined. -from Author