The North Atlantic Oscillation (NAO) is one of the most prominent and recurrent patterns of atmospheric circulation variability. It dictates climate variability from the eastern seaboard of the United States to Siberia and from the Arctic to the subtropical Atlantic, especially during boreal winter, so variations in the NAO are important to society and for the environment. Understanding the pro...

We show that the observed zonally averaged jet in the Northern Hemisphere atmosphere exhibits two spatial patterns with broadband variability in the decadal and inter-decadal range; these patterns are consistent with an important role of local, mid-latitude ocean–atmosphere coupling. A key aspect of this behaviour is the fundamentally nonlinear bi-stability of the atmospheric jet’s latitudinal ...

An advantage of using chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF6) as tracers of ocean circulation is that the time-dependent source functions permit calculation of rates for ocean processes. These compounds are also sensitive indicators highlighting interior ocean regions where surface-derived anomalies can be transported on timescales of decades. Significant applications for CFCs ...

The potential impact of Indian Ocean sea surface temperature (SST) anomalies in modulating mid-latitude precipitation across southern and western regions of Australia is assessed in a series of atmospheric general circulation model (AGCM) simulations. Two sets of AGCM integrations forced with a seasonally evolving characteristic dipole pattern in Indian Ocean SST consistent with observed “dry-y...

Interdecadal variability in the North Pacific region is investigated in a 500-y control integration of the Hamburg ECHAMcLSG coupled ocean-atmosphere general circulation model. The spectrum is predominantly red, but a significant peak with a period of about 18 y is detected in the spectrum of sea surface temperature (SST). This peak is shown to be associated with an irregular oscillation that i...

Abstract Decadal sea surface temperature (SST) fluctuations in the North Atlantic Ocean influence climate over adjacent land areas and are a major source of skill predictions. However, mechanisms underlying decadal SST variability remain to be fully understood. This study isolates driving on time scales using low-frequency component analysis, which identifies spatial temporal structure variabil...

Major anomaly patterns of annual tree-ring growth in “drought-sensitive’’ trees of the Western United States, 1931-1962, seem to reflect corresponding patterns in monthly precipitation amounts, which in turn may be related to circulation anomalies. The three most important anomaly patterns that dominated the 1931-1962 period were also prominent in the tree-growth data during the preceding perio...

The extended-range forecast skill of the ECMWF operational forecast model is evaluated during tropical intraseasonal oscillation (ISO) events in the IndoWest Pacific warm pool. The experiment consists of ensemble extended serial forecasts including winter and summer ISO cases. The forecasts are compared with the ERA-40 analyses. The analysis focuses on understanding the origin of forecast error...

Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Abstract Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Abstract In the Pliocene Model Intercomparison Project (PlioMIP), two sets of experiments are suggested. One includes a reference and a mid-Pliocene experiment run with atmosphere general circulation models (AGCM experiments, re...