Timescale dependency of spatial patterns in the variability of the Northern Hemisphere winter SLP field



[1] The Arctic Oscillation (AO), the North Atlantic Oscillation (NAO) and the Cold Ocean-Warm Land Pattern (COWL) have been identified as important modes of variability in the Northern Hemisphere winter sea-level pressure field. However, which one is most fundamental in describing this variability and the relationship between them are still important open questions. A key uncertainty is our lack of knowledge of the linkages between the Arctic, North Atlantic and North Pacific Oceans that are manifest in these modes. In this study, the authors investigate these linkages through a frequency dependent decomposition of the variability in the Northern Hemisphere sea-level pressure field. In particular, the authors show that the spatial expression of the variability in this field has a frequency dependence that results in a NAO-like pattern on inter-annual timescales, an AO-like pattern on inter-decadal timescales and a COWL-like pattern on multi-decadal timescales.