Multiyear predictability of atmospheric angular momentum and its implications.

Initialised climate predictions demonstrate ultra long-range predictability of atmospheric angular momentum, Earth's rotation and length of day. We show how slow, poleward propagating anomalies in the atmospheric angular momentum field allow interannual 'memory', well beyond currently assumed limits of atmospheric predictability. The mechanism involves wave-mean flow interaction between transient eddies and zonal winds in the troposphere and supports the persistence and poleward migration of both positive and negative anomalies. We discuss some of the implications and opportunities this presents for multiyear prediction and show how it leads to new teleconnections that are important for interpreting the observed record of climate variability.